EXHIBIT 4.1

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                   WELLS FARGO ASSET SECURITIES CORPORATION

                                   (Depositor)

                                       and

                             WELLS FARGO BANK, N.A.

                                (Master Servicer)

                                       and

                       HSBC BANK USA, NATIONAL ASSOCIATION

                                    (Trustee)

                         POOLING AND SERVICING AGREEMENT

                           Dated as of March 28, 2007

                                $1,800,061,020.00

                       Mortgage Pass-Through Certificates
                                  Series 2007-4


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<PAGE>


                                TABLE OF CONTENTS


                                    ARTICLE I

                                   DEFINITIONS

Section 1.01  Definitions..................................................
Section 1.02  Acts of Holders..............................................
Section 1.03  Effect of Headings and Table of Contents.....................
Section 1.04  Benefits of Agreement........................................


                                   ARTICLE II

                          CONVEYANCE OF MORTGAGE LOANS;
                      ORIGINAL ISSUANCE OF THE CERTIFICATES

Section 2.01  Conveyance of Mortgage Loans.................................
Section 2.02  Acceptance by Custodian......................................
Section 2.03  Representations and Warranties of the Master Servicer and
               the Depositor...............................................
Section 2.04  Execution and Delivery of Certificates.......................
Section 2.05  Designation of Certificates; Designation of Startup Day
               and Latest Possible Maturity Date...........................


                                   ARTICLE III

                ADMINISTRATION OF THE TRUST ESTATE; SERVICING
                              OF THE MORTGAGE LOANS

Section 3.01  Certificate Account..........................................
Section 3.02  Permitted Withdrawals from the Certificate Account...........
Section 3.03  Advances by Master Servicer and Trustee......................
Section 3.04  Custodian to Cooperate; Release of Owner Mortgage Loan
               Files and Retained Mortgage Loan Files......................
Section 3.05  Annual Compliance Statements.................................
Section 3.06  Title, Management and Disposition of Any REO Mortgage
               Loan........................................................
Section 3.07  Amendments to Servicing Agreements, Modification of
               Standard Provisions.........................................
Section 3.08  Oversight of Servicing.......................................
Section 3.09  Termination and Substitution of Servicing Agreements.........
Section 3.10  Application of Net Liquidation Proceeds......................
Section 3.11  Assessment of Servicing Compliance; Registered Public
               Accounting Firm Attestation Reports.........................
Section 3.12  Exchange Act Reports.........................................


                                   ARTICLE IV

                  DISTRIBUTIONS IN RESPECT OF CERTIFICATES;
                         PAYMENTS TO CERTIFICATEHOLDERS;
                             STATEMENTS AND REPORTS

Section 4.01  Distributions................................................
Section 4.02  Allocation of Realized Losses................................
Section 4.03  Paying Agent.................................................
Section 4.04  Statements to Certificateholders; Reports to the Trustee
               and the Depositor...........................................
Section 4.05  Grantor Trust Administration.................................
Section 4.06  Calculation of Amounts; Binding Effect of Interpretations
               and Actions of Master Servicer..............................
Section 4.07  Reserve Fund.................................................


                                    ARTICLE V

                                THE CERTIFICATES

Section 5.01  The Certificates.............................................
Section 5.02  Registration of Certificates.................................
Section 5.03  Mutilated, Destroyed, Lost or Stolen Certificates............
Section 5.04  Persons Deemed Owners........................................
Section 5.05  Access to List of Certificateholders' Names and Addresses....
Section 5.06  Maintenance of Office or Agency..............................
Section 5.07  Definitive Certificates......................................
Section 5.08  Notices to Clearing Agency...................................


                                   ARTICLE VI

                      THE DEPOSITOR AND THE MASTER SERVICER

Section 6.01  Liability of the Depositor and the Master Servicer...........
Section 6.02  Merger or Consolidation of the Depositor or the Master
               Servicer....................................................
Section 6.03  Limitation on Liability of the Depositor, the Master
               Servicer and Others.........................................
Section 6.04  Resignation of the Master Servicer...........................
Section 6.05  Compensation to the Master Servicer..........................
Section 6.06  Assignment or Delegation of Duties by Master Servicer........
Section 6.07  Indemnification of Trustee and Depositor by Master
               Servicer....................................................
Section 6.08  Master Servicer Errors and Omissions Policy..................


                                   ARTICLE VII

                                     DEFAULT

Section 7.01  Events of Default............................................
Section 7.02  Other Remedies of Trustee....................................
Section 7.03  Directions by Certificateholders and Duties of Trustee
               During Event of Default.....................................
Section 7.04  Action upon Certain Failures of the Master Servicer and
               upon Event of Default.......................................
Section 7.05  Trustee to Act; Appointment of Successor.....................
Section 7.06  Notification to Certificateholders...........................


                                  ARTICLE VIII

                             CONCERNING THE TRUSTEE

Section 8.01  Duties of Trustee............................................
Section 8.02  Certain Matters Affecting the Trustee........................
Section 8.03  Trustee Not Required to Make Investigation...................
Section 8.04  Trustee Not Liable for Certificates or Mortgage Loans........
Section 8.05  Trustee May Own Certificates.................................
Section 8.06  The Master Servicer to Pay Fees and Expenses; Limitation
               on Liability................................................
Section 8.07  Eligibility Requirements.....................................
Section 8.08  Resignation and Removal......................................
Section 8.09  Successor....................................................
Section 8.10  Merger or Consolidation......................................
Section 8.11  Authenticating Agent.........................................
Section 8.12  Separate Trustees and Co-Trustees............................
Section 8.13  Tax Matters; Compliance with REMIC Provisions................
Section 8.14  Monthly Advances.............................................
Section 8.15  Indemnification of the Master Servicer and Depositor by
               the Trustee.................................................
Section 8.16  Trustee Errors and Omissions Policy..........................


                                   ARTICLE IX

                                   TERMINATION

Section 9.01  Termination upon Purchase by the Depositor or Liquidation
               of All Mortgage Loans.......................................
Section 9.02  Additional Termination Requirements..........................


                                    ARTICLE X

                            MISCELLANEOUS PROVISIONS

Section 10.01 Amendment....................................................
Section 10.02 Recordation of Agreement.....................................
Section 10.03 Limitation on Rights of Certificateholders...................
Section 10.04 Governing Law; Jurisdiction..................................
Section 10.05 Notices......................................................
Section 10.06 Severability of Provisions...................................
Section 10.07 Special Notices to Rating Agencies...........................
Section 10.08 Covenant of Depositor........................................
Section 10.09 Recharacterization...........................................
Section 10.10 Regulation AB Compliance; Intent of Parties;
               Reasonableness..............................................


                                   ARTICLE XI

                             TERMS FOR CERTIFICATES

Section 11.01 Cut-Off Date.................................................
Section 11.02 Cut-Off Date Aggregate Principal Balance.....................
Section 11.03 Original Class A Percentage..................................
Section 11.04 Original Principal Balances of the Classes of Class A
               Certificates................................................
Section 11.05 Original Notional Amount.....................................
Section 11.06 Original Aggregate Non-PO Principal Balance..................
Section 11.07 Original Class B Principal Balance...........................
Section 11.08 Original Principal Balances of the Classes of Class B
               Certificates................................................
Section 11.09 Original Class B-1 Fractional Interest.......................
Section 11.10 Original Class B-2 Fractional Interest.......................
Section 11.11 Original Class B-3 Fractional Interest.......................
Section 11.12 Original Class B-4 Fractional Interest.......................
Section 11.13 Original Class B-5 Fractional Interest.......................
Section 11.14 Original Class B-1 Percentage................................
Section 11.15 Original Class B-2 Percentage................................
Section 11.16 Original Class B-3 Percentage................................
Section 11.17 Original Class B-4 Percentage................................
Section 11.18 Original Class B-5 Percentage................................
Section 11.19 Original Class B-6 Percentage................................
Section 11.20 Closing Date.................................................
Section 11.21 Right to Purchase............................................
Section 11.22 Single Certificate...........................................
Section 11.23 Servicing Fee Rate...........................................
Section 11.24 Master Servicing Fee Rate....................................
SCHEDULE I           -        Applicable Unscheduled Principal Receipt Period
SCHEDULE II          -        Schedules of PAC I Group, PAC II Certificates
                              and Scheduled Certificates

<PAGE>

                                    EXHIBITS

EXHIBIT A-1             -     Form of Face of Class A-1 Certificate
EXHIBIT A-2             -     Form of Face of Class A-2 Certificate
EXHIBIT A-3             -     Form of Face of Class A-3 Certificate
EXHIBIT A-4             -     Form of Face of Class A-4 Certificate
EXHIBIT A-5             -     Form of Face of Class A-5 Certificate
EXHIBIT A-6             -     Form of Face of Class A-6 Certificate
EXHIBIT A-7             -     Form of Face of Class A-7 Certificate
EXHIBIT A-8             -     Form of Face of Class A-8 Certificate
EXHIBIT A-9             -     Form of Face of Class A-9 Certificate
EXHIBIT A-10            -     Form of Face of Class A-10 Certificate
EXHIBIT A-11            -     Form of Face of Class A-11 Certificate
EXHIBIT A-12            -     Form of Face of Class A-12 Certificate
EXHIBIT A-13            -     Form of Face of Class A-13 Certificate
EXHIBIT A-14            -     Form of Face of Class A-14 Certificate
EXHIBIT A-15            -     Form of Face of Class A-15 Certificate
EXHIBIT A-16            -     Form of Face of Class A-16 Certificate
EXHIBIT A-17            -     Form of Face of Class A-17 Certificate
EXHIBIT A-18            -     Form of Face of Class A-18 Certificate
EXHIBIT A-19            -     Form of Face of Class A-19 Certificate
EXHIBIT A-20            -     Form of Face of Class A-20 Certificate
EXHIBIT A-21            -     Form of Face of Class A-21 Certificate
EXHIBIT A-PO            -     Form of Face of Class A-PO Certificate
EXHIBIT A-R             -     Form of Face of Class A-R Certificate
EXHIBIT B-1             -     Form of Face of Class B-1 Certificate
EXHIBIT B-2             -     Form of Face of Class B-2 Certificate
EXHIBIT B-3             -     Form of Face of Class B-3 Certificate
EXHIBIT B-4             -     Form of Face of Class B-4 Certificate
EXHIBIT B-5             -     Form of Face of Class B-5 Certificate
EXHIBIT B-6             -     Form of Face of Class B-6 Certificate
EXHIBIT C               -     Form of Reverse of Series 2007-4 Certificates
EXHIBIT D               -     Reserved
EXHIBIT E               -     Custodial Agreement
EXHIBIT F               -     Addresses for Requesting Mortgage Loan Schedule
EXHIBIT G               -     Request for Release
EXHIBIT H               -     Affidavit Pursuant to Section 860E(e)(4) of the
                              Internal Revenue Code of 1986, as amended, and
                              for Non-ERISA Investors
EXHIBIT I               -     Letter from Transferor of Residual Certificate
EXHIBIT J               -     Transferee's Letter (Class [B-4] [B-5] [B-6]
                              Certificates)
EXHIBIT K               -     List of Recordation States
EXHIBIT L               -     Servicing Agreements
EXHIBIT M               -     Form of Special Servicing Agreement
EXHIBIT N               -     Form of Initial Certification of the Custodian
EXHIBIT O               -     Form of Final Certification of the Custodian
EXHIBIT P               -     Form of Sarbanes Oxley Certification
EXHIBIT Q               -     Reserved
EXHIBIT R               -     Servicing Criteria to be Addressed in
                              Assessment of Compliance
EXHIBIT S               -     Additional Form 10-D Disclosure
EXHIBIT T               -     Additional Form 10-K Disclosure
EXHIBIT U               -     Form 8-K Disclosure Information
EXHIBIT V               -     Additional Disclosure Notification
EXHIBIT W               -     Yield Maintenance Agreement
EXHIBIT X               -     Form of Yield Maintenance Agreement Letter

<PAGE>

            This Pooling and Servicing Agreement, dated as of March 28, 2007
executed by WELLS FARGO ASSET SECURITIES CORPORATION, as Depositor, WELLS FARGO
BANK, N.A., as Master Servicer and HSBC BANK USA, NATIONAL ASSOCIATION, as
Trustee.

                          W I T N E S S E T H  T H A T:

            In consideration of the mutual agreements herein contained, the
Depositor, the Master Servicer and the Trustee agree as follows:

                                    ARTICLE I

                                   DEFINITIONS

            Section 1.01 Definitions.

            Whenever used herein, the following words and phrases, unless the
context otherwise requires, shall have the meanings specified in this Article.

            1933 Act: The Securities Act of 1933, as amended.

            Accepted Master Servicing Practices: Accepted Master Servicing
Practices shall consist of the customary and usual master servicing practices of
prudent master servicing institutions which master service mortgage loans of the
same type as the Mortgage Loans in the jurisdictions in which the related
Mortgaged Properties are located, regardless of the date upon which the related
Mortgage Loans were originated.

            Accretion Termination Date: With respect to (a) the Class A-10
Certificates, the earlier to occur of (i) the Distribution Date following the
Distribution Date on which the Principal Balances of the Class A-5 and Class A-6
Certificates have been reduced to zero or (ii) the Subordination Depletion Date
and (b) the Class A-6 Certificates, the earlier to occur of (i) the Distribution
Date following the Distribution Date on which the Principal Balance of the Class
A-5 Certificates has been reduced to zero or (ii) the Subordination Depletion
Date.

            Accrual Certificates: Either of the Class A-6 or Class A-10
Certificates.

            Accrual Distribution Amount: As to any Distribution Date prior to
the applicable Accretion Termination Date and a Class of Accrual Certificates,
an amount equal to the sum of (i) the Class A Interest Percentage of such Class
of Accrual Certificates of the Current Class A Interest Distribution Amount and
(ii) the Class A Interest Shortfall Percentage of such Class of Accrual
Certificates of the amount distributed in respect of the Classes of Class A
Certificates pursuant to Paragraph second of Section 4.01(a) on such
Distribution Date. As to any Distribution Date and a Class of Accrual
Certificates on or after the applicable Accretion Termination Date, zero.

            Additional Form 10-D Disclosure: As defined in Section 3.12(a).

            Additional Form 10-K Disclosure: As defined in Section 3.12(b).

            Additional Master Servicer: As defined in Section 6.06(b).

            Adjusted Pool Amount: With respect to any Distribution Date, the
Cut-Off Date Aggregate Principal Balance of the Mortgage Loans minus the sum of
(i) all amounts in respect of principal received in respect of the Mortgage
Loans (including, without limitation, amounts received as Monthly Payments,
Periodic Advances, Unscheduled Principal Receipts and Substitution Principal
Amounts) and distributed to Holders of the Certificates on such Distribution
Date and all prior Distribution Dates, (ii) the principal portion of all
Liquidated Loan Losses incurred on such Mortgage Loans for which the Liquidation
Proceeds were received from the Cut-Off Date through the end of the Applicable
Unscheduled Principal Receipt Period with respect to Full Unscheduled Principal
Receipts for such Distribution Date and (iii) the principal portion of all
Bankruptcy Losses (other than Debt Service Reductions) incurred on the Mortgage
Loans from the Cut-Off Date through the end of the period corresponding to the
Applicable Unscheduled Principal Receipt Period with respect to Full Unscheduled
Principal Receipts for such Distribution Date.

            Adjusted Pool Amount (Non-PO Portion): With respect to any
Distribution Date, the difference between the Adjusted Pool Amount and the
Adjusted Pool Amount (PO Portion).

            Adjusted Pool Amount (PO Portion): With respect to any Distribution
Date, the sum of the amounts, calculated as follows, with respect to all
Outstanding Mortgage Loans: the product of (i) the PO Fraction for each such
Mortgage Loan and (ii) the remainder of (A) the Cut-Off Date Principal Balance
of such Mortgage Loan minus (B) the sum of (x) all amounts in respect of
principal received in respect of such Mortgage Loan (including, without
limitation, amounts received as Monthly Payments, Periodic Advances, Unscheduled
Principal Receipts and Substitution Principal Amounts) and distributed to
Holders of the Certificates on such Distribution Date and all prior Distribution
Dates, (y) the principal portion of any Liquidated Loan Losses incurred on such
Mortgage Loans for which Liquidation Proceeds were received from the Cut-Off
Date through the end of the Applicable Unscheduled Principal Receipt Period with
respect to Full Unscheduled Principal Receipts for such Distribution Date and
(z) the principal portion of all Bankruptcy Losses (other than Debt Service
Reductions) incurred on the Mortgage Loans from the Cut-Off Date through the end
of the period corresponding to the Applicable Unscheduled Principal Receipt
Period with respect to Full Unscheduled Principal Receipts for such Distribution
Date.

            Adjusted Principal Balance: As to any Distribution Date and any
Class of Class B Certificates, the greater of (A) zero and (B) (i) the Principal
Balance of such Class with respect to such Distribution Date minus (ii) the
Adjustment Amount for such Distribution Date less the Principal Balances for any
Classes of Class B Certificates with higher numerical designations.

            Adjustment Amount: For any Distribution Date, the difference between
(A) the sum of the Class A Non-PO Principal Balance and the Class B Principal
Balance as of the related Determination Date and (B) the sum of (i) the sum of
the Class A Non-PO Principal Balance and the Class B Principal Balance as of the
Determination Date succeeding such Distribution Date and (ii) the aggregate
amount that would have been distributed to all Classes (other than the Class
A-PO Certificates) as principal in accordance with Section 4.01(a) for such
Distribution Date without regard to the provisos in the definitions of Class B-1
Optimal Principal Amount, Class B-2 Optimal Principal Amount, Class B-3 Optimal
Principal Amount, Class B-4 Optimal Principal Amount, Class B-5 Optimal
Principal Amount and Class B-6 Optimal Principal Amount.

            Aggregate Class A Unpaid Interest Shortfall: As to any Distribution
Date, an amount equal to the sum of the Class A Unpaid Interest Shortfalls for
all the Classes of Class A Certificates.

            Aggregate Non-PO Principal Balance: As of any Determination Date,
the sum of the Class A Non-PO Principal Balance and the Class B Principal
Balance as of such date.

            Agreement: This Pooling and Servicing Agreement and all amendments
and supplements hereto.

            Applicable Unscheduled Principal Receipt Period: With respect to the
Mortgage Loans serviced by each Servicer and each of the Full Unscheduled
Principal Receipts and Partial Unscheduled Principal Receipts, the Unscheduled
Principal Receipt Period specified on Schedule I hereto, as amended by the
Master Servicer pursuant to Section 10.01(b) hereof.

            Authenticating Agent: Any authenticating agent appointed by the
Trustee pursuant to Section 8.11. Initially, the Master Servicer shall be the
Authenticating Agent for the Certificates.

            Available Master Servicer Compensation: With respect to any
Distribution Date, the sum of (a) the Master Servicing Fee for such Distribution
Date, (b) interest earned through the business day preceding the applicable
Distribution Date on any Prepayments in Full remitted to the Master Servicer and
(c) the aggregate amount of Month End Interest remitted by the Servicers to the
Master Servicer pursuant to the related Servicing Agreements.

            Balloon Loan: A Mortgage Loan that provides for the payment of the
unamortized principal balance of such Mortgage Loan in a single payment at the
maturity of such Mortgage Loan that is greater than the preceding monthly
payment.

            Balloon Payment: A payment of the unamortized principal balance of a
Mortgage Loan in a single payment at the maturity of such Mortgage Loan that is
greater than the preceding Monthly Payment.

            Bankruptcy Code: The Bankruptcy Code of 1978, as amended.

            Bankruptcy Loss: With respect to any Mortgage Loan, a Deficient
Valuation or Debt Service Reduction; provided, however, that a Bankruptcy Loss
shall not be deemed a Bankruptcy Loss hereunder so long as the applicable
Servicer has notified the Master Servicer and the Trustee in writing that such
Servicer is diligently pursuing any remedies that may exist in connection with
the representations and warranties made regarding the related Mortgage Loan and
either (A) the related Mortgage Loan is not in default with regard to payments
due thereunder or (B) delinquent payments of principal and interest under the
related Mortgage Loan and any premiums on any applicable primary hazard
insurance policy and any related escrow payments in respect of such Mortgage
Loan are being advanced on a current basis by such Servicer without giving
effect to any Debt Service Reduction.

            Beneficial Owner: With respect to a Book-Entry Certificate, the
Person who is the beneficial owner of such Book-Entry Certificate, as reflected
on the books of the Clearing Agency, or on the books of a Person maintaining an
account with such Clearing Agency (directly or as an indirect participant, in
accordance with the rules of such Clearing Agency), as the case may be.

            Book-Entry Certificate: Any one of the Class A-1 Certificates, Class
A-2 Certificates, Class A-3 Certificates, Class A-4 Certificates, Class A-5
Certificates, Class A-6 Certificates, Class A-7 Certificates, Class A-8
Certificates, Class A-9 Certificates, Class A-10 Certificates, Class A-11
Certificates, Class A-12 Certificates, Class A-13 Certificates, Class A-14
Certificates, Class A-15 Certificates, Class A-16 Certificates, Class A-17
Certificates, Class A-18 Certificates, Class A-19 Certificates, Class A-20
Certificates, Class A-21 Certificates, Class A-PO Certificates, Class B-1
Certificates, Class B-2 Certificates, Class B-3 Certificates, Class B-4
Certificates, Class B-5 Certificates and Class B-6 Certificates, beneficial
ownership and transfers of which shall be evidenced by, and made through, book
entries by the Clearing Agency as described in Section 5.01(b).

            Business Day: Any day other than (i) a Saturday or a Sunday, or (ii)
a legal holiday in the City of New York, State of Iowa, State of Maryland or
State of Minnesota or (iii) a day on which banking institutions in the City of
New York, or the State of Iowa, State of Maryland or State of Minnesota are
authorized or obligated by law or executive order to be closed.

            Certificate: Any one of the Class A Certificates or Class B
Certificates.

            Certificate Account: The separate trust account established and
maintained by the Master Servicer pursuant to Section 3.01 which shall be
entitled "Certificate Account, Wells Fargo Bank, N.A., as Master Servicer on
behalf of the Trustee, in trust for the Holders of the Certificates of the Wells
Fargo Mortgage Backed Securities 2007-4 Trust." The Certificate Account shall be
an Eligible Account.

            Certificate Custodian: Initially, Wells Fargo Bank; thereafter any
other Certificate Custodian acceptable to The Depository Trust Company and
selected by the Trustee.

            Certificate Register and Certificate Registrar: Respectively, the
register maintained pursuant to and the registrar provided for in Section 5.02.
Initially the Certificate Registrar shall be the Master Servicer.

            Certificateholder or Holder: The Person in whose name a Certificate
is registered in the Certificate Register, except that, solely for the purposes
of the taking of any action under Articles VII or VIII, any Certificate
registered in the name of the Master Servicer, a Servicer or any affiliate
thereof shall be deemed not to be outstanding and the Voting Interest evidenced
thereby shall not be taken into account in determining whether the requisite
percentage of Certificates necessary to effect any such action has been
obtained.

            Class: All certificates whose form is identical except for
variations in the Percentage Interest evidenced thereby.

            Class A Certificate: Any of the Class A-1 Certificates, Class A-2
Certificates, Class A-3 Certificates, Class A-4 Certificates, Class A-5
Certificates, Class A-6 Certificates, Class A-7 Certificates, Class A-8
Certificates, Class A-9 Certificates, Class A-10 Certificates, Class A-11
Certificates, Class A-12 Certificates, Class A-13 Certificates, Class A-14
Certificates, Class A-15 Certificates, Class A-16 Certificates, Class A-17
Certificates, Class A-18 Certificates, Class A-19 Certificates, Class A-20
Certificates, Class A-21 Certificates, Class A-PO Certificates and Class A-R
Certificate.

            Class A Certificateholder: The registered holder of a Class A
Certificate.

            Class A Distribution Amount: As to any Distribution Date and any
Class of Class A Certificates (other than the Classes of Accrual Certificates
and the Interest Only Certificates and Class A-PO Certificates), the amount
distributable to such Class of Class A Certificates pursuant to Paragraphs
first, second and third clause (1) of Section 4.01(a). As to a Class of Accrual
Certificates, (a) as to any Distribution Date prior to the applicable Accretion
Termination Date, the amount distributable to such Class of Accrual Certificates
pursuant to the provisos in Paragraphs first and second of Section 4.01(a) and
Paragraph third clause (1) of Section 4.01(a) and (b) as to any Distribution
Date on or after the applicable Accretion Termination Date, the amount
distributable to such Class of Accrual Certificates pursuant to Paragraphs
first, second and third of Section 4.01(a). As to any Distribution Date and the
Interest Only Certificates, the amount distributable to such Class pursuant to
Paragraphs first and second of Section 4.01(a) on such Distribution Date. As to
any Distribution Date and the Class A-PO Certificates, the amount distributable
to the Class A-PO Certificates pursuant to Paragraphs third clause (2) and
fourth of Section 4.01(a) on such Distribution Date.

            Class A Interest Accrual Amount: As to any Distribution Date, the
sum of the Interest Accrual Amounts for the Class A Certificates with respect to
such Distribution Date.

            Class A Interest Percentage: As to any Distribution Date and any
Class of Class A Certificates, the percentage calculated by dividing the
Interest Accrual Amount of such Class (determined without regard to clause (ii)
of the definition thereof) by the Class A Interest Accrual Amount (determined
without regard to clause (ii) of the definition of each Interest Accrual
Amount).

            Class A Interest Shortfall Amount: As to any Distribution Date and
any Class of Class A Certificates, any amount by which the Interest Accrual
Amount of such Class with respect to such Distribution Date exceeds the amount
distributed in respect of such Class on such Distribution Date pursuant to
Paragraph first of Section 4.01(a) including, in the case of a Class of Accrual
Certificates prior to the applicable Accretion Termination Date, the amount
included in the Accrual Distribution Amount pursuant to clause (i) of the
definition thereof.

            Class A Interest Shortfall Percentage: As to any Distribution Date
and any Class of Class A Certificates, the percentage calculated by dividing the
Class A Unpaid Interest Shortfall for such Class by the Aggregate Class A Unpaid
Interest Shortfall, in each case determined as of the day preceding the
applicable Distribution Date.

            Class A Loss Denominator: As to any Determination Date, the sum of
(i) an amount equal to the Class A Non-PO Principal Balance (less the Principal
Balances of the Classes of Accrual Certificates) and (ii) with respect to a
Class of Accrual Certificates, the lesser of the Principal Balance of such Class
of Accrual Certificates and the Original Principal Balance of such Class of
Accrual Certificates.

            Class A Loss Percentage: As to any Determination Date and any Class
of Class A Certificates (other than the Class A-PO Certificates), the percentage
calculated by dividing the Principal Balance of such Class (or, in the case of a
Class of Accrual Certificates, the Original Principal Balance of such Class of
Accrual Certificates, if lower) by the Class A Loss Denominator (determined
without regard to any such Principal Balance of any Class of Class A
Certificates not then outstanding), in each case determined as of the preceding
Determination Date.

            Class A Non-PO Certificate: Any of the Class A-1 Certificates, Class
A-2 Certificates, Class A-3 Certificates, Class A-4 Certificates, Class A-5
Certificates, Class A-6 Certificates, Class A-7 Certificates, Class A-8
Certificates, Class A-9 Certificates, Class A-10 Certificates, Class A-11
Certificates, Class A-12 Certificates, Class A-13 Certificates, Class A-14
Certificates, Class A-15 Certificates, Class A-16 Certificates, Class A-17
Certificates, Class A-18 Certificates, Class A-19 Certificates, Class A-20
Certificates, Class A-21 Certificates and Class A-R Certificate.

            Class A Non-PO Optimal Amount: As to any Distribution Date, the sum
for such Distribution Date of (i) the Class A Interest Accrual Amount, (ii) the
Aggregate Class A Unpaid Interest Shortfall and (iii) the Class A Non-PO Optimal
Principal Amount.

            Class A Non-PO Optimal Principal Amount: As to any Distribution
Date, an amount equal to the sum of (I) the sum, as to each Mortgage Loan that
is an Outstanding Mortgage Loan, of the product of (x) the Non-PO Fraction with
respect to such Mortgage Loan, and (y) the sum of:

            (i) the Class A Percentage of the principal portion of the Monthly
      Payment due on the Due Date occurring in the month of such Distribution
      Date on such Mortgage Loan;

            (ii) the Class A Prepayment Percentage of all Unscheduled Principal
      Receipts (other than Recoveries) that were received by a Servicer with
      respect to such Mortgage Loan during the Applicable Unscheduled Principal
      Receipt Period relating to such Distribution Date for each applicable type
      of Unscheduled Principal Receipt;

            (iii) the Class A Prepayment Percentage of the Scheduled Principal
      Balance of such Mortgage Loan which, during the one month period ending on
      the day preceding the Determination Date for such Distribution Date, was
      repurchased by the Depositor pursuant to Section 2.02, 2.03 or 3.08; and

            (iv) the Class A Percentage of the Substitution Principal Amount
      with respect to each Mortgage Loan for which a Mortgage Loan was
      substituted during the one month period ending on the day preceding the
      Determination Date for such Distribution Date, less the amount allocable
      to the principal portion of any unreimbursed Periodic Advances previously
      made by the applicable Servicer, the Master Servicer or the Trustee in
      respect of such Mortgage Loan for which a Mortgage Loan was substituted;
      and

      (II) the Class A Prepayment Percentage of the Non-PO Recovery for such
      Distribution Date.

            Class A Non-PO Principal Balance: As of any date, an amount equal to
the Class A Principal Balance less the Principal Balance of the Class A-PO
Certificates.

            Class A Non-PO Principal Distribution Amount: As to any Distribution
Date, the aggregate amount distributed in respect of the Classes of A
Certificates pursuant to Paragraph third clause (1) of Section 4.01(a).

            Class A Pass-Through Rate: As to the Class A-1, Class A-2, Class
A-3, Class A-4, Class A-5, Class A-6, Class A-8, Class A-9, Class A-10, Class
A-12, Class A-13, Class A-14, Class A-15, Class A-19 and Class A-R Certificates,
6.000% per annum. As to the Class A-7 Certificates, 5.750% per annum. As to the
Class A-11 Certificates, 6.500% per annum. As to the Class A-16, Class 17, Class
A-18, Class A-20 and Class A-21 Certificates, 5.500% per annum. The Class A-PO
Certificates are not entitled to interest and have no Class A Pass-Through Rate.

            Class A Percentage: As to any Distribution Date occurring on or
prior to the Subordination Depletion Date, the lesser of (i) 100% and (ii) the
percentage obtained by dividing the Class A Non-PO Principal Balance (determined
as of the Determination Date preceding such Distribution Date) by the Pool
Balance (Non-PO Portion). As to any Distribution Date occurring subsequent to
the Subordination Depletion Date, 100% or such lesser percentage which will
cause the Class A Non-PO Principal Balance to decline to zero following the
distribution made on such Distribution Date.

            Class A Prepayment Percentage: As to any Distribution Date to and
including the Distribution Date in March 2012, 100%. As to any Distribution Date
subsequent to March 2012 to and including the Distribution Date in March 2013,
the Class A Percentage as of such Distribution Date plus 70% of the Subordinated
Percentage as of such Distribution Date. As to any Distribution Date subsequent
to March 2013 to and including the Distribution Date in March 2014, the Class A
Percentage as of such Distribution Date plus 60% of the Subordinated Percentage
as of such Distribution Date. As to any Distribution Date subsequent to March
2014 to and including the Distribution Date in March 2015, the Class A
Percentage as of such Distribution Date plus 40% of the Subordinated Percentage
as of such Distribution Date. As to any Distribution Date subsequent to March
2015 to and including the Distribution Date in March 2016, the Class A
Percentage as of such Distribution Date plus 20% of the Subordinated Percentage
as of such Distribution Date. As to any Distribution Date subsequent to March
2016, the Class A Percentage as of such Distribution Date. The foregoing is
subject to the following: (i) if the aggregate distribution to Holders of Class
A Certificates on any Distribution Date of the Class A Prepayment Percentage
provided above of Unscheduled Principal Receipts distributable on such
Distribution Date would reduce the Class A Non-PO Principal Balance below zero,
the Class A Prepayment Percentage for such Distribution Date shall be the
percentage necessary to bring the Class A Non-PO Principal Balance to zero and
thereafter the Class A Prepayment Percentage shall be zero and (ii) if the Class
A Percentage as of any Distribution Date is greater than the Original Class A
Percentage, the Class A Prepayment Percentage for such Distribution Date shall
be 100%. Notwithstanding the foregoing, with respect to any Distribution Date on
which the following criteria are not met, the reduction of the Class A
Prepayment Percentage described in the second through sixth sentences of this
definition of Class A Prepayment Percentage shall not be applicable with respect
to such Distribution Date. In such event, the Class A Prepayment Percentage for
such Distribution Date will be determined in accordance with the applicable
provision, as set forth in the first through fifth sentences above, which was
actually used to determine the Class A Prepayment Percentage for the
Distribution Date occurring in the March preceding such Distribution Date (it
being understood that for the purposes of the determination of the Class A
Prepayment Percentage for the current Distribution Date, the current Class A
Percentage and Subordinated Percentage shall be utilized).

            No reduction in the Class A Prepayment Percentage referred to in the
second through sixth sentences hereof shall be applicable, with respect to any
Distribution Date if (a) the average outstanding principal balance on such
Distribution Date and for the preceding five Distribution Dates on the Mortgage
Loans that were delinquent 60 days or more (including for this purpose any
payments due with respect to Mortgage Loans in foreclosure and REO Mortgage
Loans) were greater than or equal to 50% of the Class B Principal Balance or (b)
cumulative Realized Losses on the Mortgage Loans exceed (1) 30% of the Original
Class B Principal Balance if such Distribution Date occurs between and including
April 2012 and March 2013, (2) 35% of the Original Class B Principal Balance if
such Distribution Date occurs between and including April 2013 and March 2014,
(3) 40% of the Original Class B Principal Balance if such Distribution Date
occurs between and including April 2014 and March 2015, (4) 45% of the Original
Class B Principal Balance if such Distribution Date occurs between and including
April 2015 and March 2016, and (5) 50% of the Original Class B Principal Balance
if such Distribution Date occurs during or after April 2016. With respect to any
Distribution Date on which the Class A Prepayment Percentage is reduced below
the Class A Prepayment Percentage for the prior Distribution Date, the Master
Servicer shall certify to the Trustee, based upon information provided by each
Servicer as to the Mortgage Loans serviced by it that the criteria set forth in
the preceding sentence are met.

            Class A Principal Balance: As of any date, an amount equal to the
sum of the Principal Balances for the Class A-1 Certificates, Class A-2
Certificates, Class A-3 Certificates, Class A-4 Certificates, Class A-5
Certificates, Class A-6 Certificates, Class A-7 Certificates, Class A-8
Certificates, Class A-9 Certificates, Class A-10 Certificates, Class A-11
Certificates, Class A-12 Certificates, Class A-13 Certificates, Class A-14
Certificates, Class A-15 Certificates, Class A-16 Certificates, Class A-17
Certificates, Class A-18 Certificates, Class A-20 Certificates, Class A-21
Certificates, Class A-PO Certificates and Class A-R Certificate.

            Class A Unpaid Interest Shortfall: As to any Distribution Date and
any Class of Class A Certificates, the amount, if any, by which the aggregate of
the Class A Interest Shortfall Amounts for such Class (or in the case of a Class
of Accrual Certificates prior to the applicable Accretion Termination Date, the
amount included in the Accrual Distribution Amount pursuant to clause (ii) of
the definition thereof) for prior Distribution Dates is in excess of the amounts
distributed in respect of such Class on prior Distribution Dates pursuant to
Paragraph second of Section 4.01(a).

            Class A-1 Certificate: Any one of the Certificates executed by the
Paying Agent and countersigned by the Authenticating Agent in substantially the
form set forth in Exhibit A-1 and Exhibit C hereto.

            Class A-1 Certificateholder: The registered holder of a Class A-1
Certificate.

            Class A-2 Certificate: Any one of the Certificates executed by the
Paying Agent and countersigned by the Authenticating Agent in substantially the
form set forth in Exhibit A-2 and Exhibit C hereto.

            Class A-2 Certificateholder: The registered holder of a Class A-2
Certificate.

            Class A-2 Loss Allocation Amount: With respect to any Determination
Date after the Subordination Depletion Date the lesser of (a) the Principal
Balance of the Class A-2 Certificates with respect to such Determination Date
prior to any reduction for the Class A-2 Loss Allocation Amount and (b) the sum
of the Class A-5 Loss Amount, Class A-8 Loss Amount, Class A-14 Loss Amount and
Class A-15 Loss Amount.

            Class A-3 Certificate: Any one of the Certificates executed by the
Paying Agent and countersigned by the Authenticating Agent in substantially the
form set forth in Exhibit A-3 and Exhibit C hereto.

            Class A-3 Certificateholder: The registered holder of a Class A-3
Certificate.

            Class A-4 Certificate: Any one of the Certificates executed by the
Paying Agent and countersigned by the Authenticating Agent in substantially the
form set forth in Exhibit A-4 and Exhibit C hereto.

            Class A-4 Certificateholder: The registered holder of a Class A-4
Certificate.

            Class A-5 Certificate: Any one of the Certificates executed by the
Paying Agent and countersigned by the Authenticating Agent in substantially the
form set forth in Exhibit A-5 and Exhibit C hereto.

            Class A-5 Certificateholder: The registered holder of a Class A-5
Certificate.

            Class A-5 Loss Amount: With respect to any Determination Date after
the Subordination Depletion Date, the amount, if any, by which the Principal
Balance of the Class A-5 Certificates would be reduced as a result of the
application of the third sentence of the definition of Principal Balance.

            Class A-6 Certificate: Any one of the Certificates executed by the
Paying Agent and countersigned by the Authenticating Agent in substantially the
form set forth in Exhibit A-6 and Exhibit C hereto.

            Class A-6 Certificateholder: The registered holder of a Class A-6
Certificate.

            Class A-7 Certificate: Any one of the Certificates executed by the
Paying Agent and countersigned by the Authenticating Agent in substantially the
form set forth in Exhibit A-7 and Exhibit C hereto.

            Class A-7 Certificateholder: The registered holder of a Class A-7
Certificate.

            Class A-7 Loss Amount: With respect to any Determination Date after
the Subordination Depletion Date, the amount, if any, by which the Principal
Balance of the Class A-7 Certificates would be reduced as a result of the
application of the third sentence of the definition of Principal Balance.

            Class A-8 Certificate: Any one of the Certificates executed by the
Paying Agent and countersigned by the Authenticating Agent in substantially the
form set forth in Exhibit A-8 and Exhibit C hereto.

            Class A-8 Certificateholder: The registered holder of a Class A-8
Certificate.

            Class A-8 Loss Amount: With respect to any Determination Date after
the Subordination Depletion Date, the amount, if any, by which the Principal
Balance of the Class A-8 Certificates would be reduced as a result of the
application of the third sentence of the definition of Principal Balance.

            Class A-9 Certificate: Any one of the Certificates executed by the
Paying Agent and countersigned by the Authenticating Agent in substantially the
form set forth in Exhibit A-9 and Exhibit C hereto.

            Class A-9 Certificateholder: The registered holder of a Class A-9
Certificate.

            Class A-10 Certificate: Any one of the Certificates executed by the
Paying Agent and countersigned by the Authenticating Agent in substantially the
form set forth in Exhibit A-10 and Exhibit C hereto.

            Class A-10 Certificateholder: The registered holder of a Class A-10
Certificate.

            Class A-11 Certificate: Any one of the Certificates executed by the
Paying Agent and countersigned by the Authenticating Agent in substantially the
form set forth in Exhibit A-11 and Exhibit C hereto.

            Class A-11 Certificateholder: The registered holder of a Class A-11
Certificate.

            Class A-12 Certificate: Any one of the Certificates executed by the
Paying Agent and countersigned by the Authenticating Agent in substantially the
form set forth in Exhibit A-12 and Exhibit C hereto.

            Class A-12 Certificateholder: The registered holder of a Class A-12
Certificate.

            Class A-12 Loss Allocation Amount: With respect to any Determination
Date after the Subordination Depletion Date the lesser of (a) the Principal
Balance of the Class A-12 Certificates with respect to such Determination Date
prior to any reduction for the Class A-12 Loss Allocation Amount and (b) the
Class A-7 Loss Amount.

            Class A-13 Certificate: Any one of the Certificates executed by the
Paying Agent and countersigned by the Authenticating Agent in substantially the
form set forth in Exhibit A-13 and Exhibit C hereto.

            Class A-13 Certificateholder: The registered holder of a Class A-13
Certificate.

            Class A-14 Certificate: Any one of the Certificates executed by the
Paying Agent and countersigned by the Authenticating Agent in substantially the
form set forth in Exhibit A-14 and Exhibit C hereto.

            Class A-14 Certificateholder: The registered holder of a Class A-14
Certificate.

            Class A-14 Loss Amount: With respect to any Determination Date after
the Subordination Depletion Date, the amount, if any, by which the Principal
Balance of the Class A-14 Certificates would be reduced as a result of the
application of the third sentence of the definition of Principal Balance.

            Class A-15 Certificate: Any one of the Certificates executed by the
Paying Agent and countersigned by the Authenticating Agent in substantially the
form set forth in Exhibit A-15 and Exhibit C hereto.

            Class A-15 Certificateholder: The registered holder of a Class A-15
Certificate.

            Class A-15 Loss Amount: With respect to any Determination Date after
the Subordination Depletion Date, the amount, if any, by which the Principal
Balance of the Class A-15 Certificates would be reduced as a result of the
application of the third sentence of the definition of Principal Balance.

            Class A-16 Certificate: Any one of the Certificates executed by the
Paying Agent and countersigned by the Authenticating Agent in substantially the
form set forth in Exhibit A-16 and Exhibit C hereto.

            Class A-16 Certificateholder: The registered holder of a Class A-16
Certificate.

            Class A-17 Certificate: Any one of the Certificates executed by the
Paying Agent and countersigned by the Authenticating Agent in substantially the
form set forth in Exhibit A-17 and Exhibit C hereto.

            Class A-17 Certificateholder: The registered holder of a Class A-17
Certificate.

            Class A-18 Certificate: Any one of the Certificates executed by the
Paying Agent and countersigned by the Authenticating Agent in substantially the
form set forth in Exhibit A-18 and Exhibit C hereto.

            Class A-18 Certificateholder: The registered holder of a Class A-18
Certificate.

            Class A-19 Certificate: Any one of the Certificates executed by the
Paying Agent and countersigned by the Authenticating Agent in substantially the
form set forth in Exhibit A-19 and Exhibit C hereto.

            Class A-19 Certificateholder: The registered holder of a Class A-19
Certificate.

            Class A-19 Notional Amount: As to any Distribution Date, an amount
equal to the sum of the Principal Balances of the Class A-16, Class A-17, Class
A-18, Class A-20 and Class A-21 Certificates divided by 12.

            Class A-20 Certificate: Any one of the Certificates executed by the
Paying Agent and countersigned by the Authenticating Agent in substantially the
form set forth in Exhibit A-20 and Exhibit C hereto.

            Class A-20 Certificateholder: The registered holder of a Class A-20
Certificate.

            Class A-21 Certificate: Any one of the Certificates executed by the
Paying Agent and countersigned by the Authenticating Agent in substantially the
form set forth in Exhibit A-21 and Exhibit C hereto.

            Class A-21 Certificateholder: The registered holder of a Class A-21
Certificate.

            Class A-L1 Interest: A regular interest in the Lower-Tier REMIC
which is held as an asset of the Upper-Tier REMIC and is entitled to monthly
distributions as provided in Section 4.01(a) hereof.

            Class A-L5 Interest: A regular interest in the Lower-Tier REMIC
which is held as an asset of the Upper-Tier REMIC and is entitled to monthly
distributions as provided in Section 4.01(a) hereof.

            Class A-L7 Interest: A regular interest in the Lower-Tier REMIC
which is held as an asset of the Upper-Tier REMIC and is entitled to monthly
distributions as provided in Section 4.01(a) hereof.

            Class A-L16 Interest: A regular interest in the Lower-Tier REMIC
which is held as an asset of the Upper-Tier REMIC and is entitled to monthly
distributions as provided in Section 4.01(a) hereof.

            Class A-LPO Interest: A regular interest in the Lower-Tier REMIC
which is held as an asset of the Upper-Tier REMIC and is entitled to monthly
distributions as provided in Section 4.01(a) hereof.

            Class A-LR Interest: The residual interest in the Lower-Tier REMIC,
beneficial ownership of which is represented by the Class A-R Certificate.

            Class A-LUR Interest: A regular interest in the Lower-Tier REMIC
which is held as an asset of the Upper-Tier REMIC and is entitled to monthly
distributions as provided in Section 4.01(a) hereof.

            Class A-PO Certificate: Any one of the Certificates executed by the
Paying Agent and countersigned by the Authenticating Agent in substantially the
form set forth in Exhibit A-PO and Exhibit C hereto.

            Class A-PO Certificateholder: The registered holder of a Class A-PO
Certificate.

            Class A-PO Deferred Amount: For any Distribution Date prior to the
Subordination Depletion Date, the difference between (A) the sum of (x) the
amount by which the sum of the Class A-PO Optimal Principal Amounts for all
prior Distribution Dates exceeded the amounts distributed on the Class A-PO
Certificates on such prior Distribution Dates pursuant to Paragraph third clause
(2) of Section 4.01(a) and (y) the sum of the product for each Discount Mortgage
Loan which became a Liquidated Loan at any time on or prior to the last day of
the Applicable Unscheduled Principal Receipt Period for Full Unscheduled
Principal Receipts for the current Distribution Date of (a) the PO Fraction for
such Discount Mortgage Loan and (b) an amount equal to the principal portion of
Realized Losses (other than Bankruptcy Losses due to Debt Service Reductions)
incurred with respect to such Discount Mortgage Loan and (B) the sum of (x) the
sum of the Class A-PO Recoveries for such Distribution Date and prior
Distribution Dates and (y) amounts distributed on the Class A-PO Certificates on
prior Distribution Dates pursuant to Paragraph fourth of Section 4.01(a). On and
after the Subordination Depletion Date, the Class A-PO Deferred Amount will be
zero. No interest will accrue on any Class A-PO Deferred Amount.

            Class A-PO Optimal Principal Amount: As to any Distribution Date, an
amount equal to the sum of (I) the sum, as to each Mortgage Loan that is an
Outstanding Mortgage Loan, of the product of (x) the PO Fraction with respect to
such Mortgage Loan and (y) the sum of:

            (i) the principal portion of the Monthly Payment due on the Due Date
      occurring in the month of such Distribution Date on such Mortgage Loan;

            (ii) all Unscheduled Principal Receipts (other than Recoveries) that
      were received by a Servicer with respect to such Mortgage Loan during the
      Applicable Unscheduled Principal Receipt Period relating to such
      Distribution Date for each applicable type of Unscheduled Principal
      Receipt;

            (iii) the Scheduled Principal Balance of each Mortgage Loan which,
      during the one month period ending on the day preceding the Determination
      Date for such Distribution Date, was repurchased by the Depositor pursuant
      to Section 2.02, 2.03 or 3.08; and

            (iv) the Substitution Principal Amount with respect to each Mortgage
      Loan for which a Mortgage Loan was substituted during the one month period
      ending on the day preceding the Determination Date for such Distribution
      Date, less the amount allocable to the principal portion of any
      unreimbursed Periodic Advances previously made by the applicable Servicer,
      the Master Servicer or the Trustee in respect of such Mortgage Loan for
      which a Mortgage Loan was substituted; and

      (II) the Class A-PO Recovery for such Distribution Date.

            Class A-PO Recovery: As to any Distribution Date prior to the
Subordination Depletion Date, the lesser of (a) the Class A-PO Deferred Amount
for such Distribution Date (calculated without regard to the Class A-PO Recovery
for such Distribution Date) and (b) an amount equal to the sum as to each
Mortgage Loan as to which there has been a Recovery during the Applicable
Unscheduled Principal Receipt Period, of the product of (x) the PO Fraction with
respect to such Mortgage Loan and (y) the amount of the Recovery with respect to
such Mortgage Loan. As to any Distribution Date on or after the Subordination
Depletion Date, the amount determined in accordance with clause (b) above.

            Class A-R Certificate: The Certificate executed by the Paying Agent
and countersigned by the Authenticating Agent in substantially the form set
forth in Exhibit A-R and Exhibit C hereto.

            Class A-R Certificateholder: The registered holder of the Class A-R
Certificate.

            Class A-R Interest: The residual interest in the Upper-Tier REMIC,
beneficial ownership of which is evidenced by the Class A-R Certificate.

            Class B Certificate: Any of the Class B-1 Certificates, Class B-2
Certificates, Class B-3 Certificates, Class B-4 Certificates, Class B-5
Certificates or Class B-6 Certificates.

            Class B Certificateholder: The registered holder of a Class B
Certificate.

            Class B Distribution Amount: Any of the Class B-1, Class B-2, Class
B-3, Class B-4, Class B-5 and Class B-6 Distribution Amounts.

            Class B Interest Accrual Amount: With respect to any Distribution
Date, the sum of the Interest Accrual Amounts for the Classes of Class B
Certificates with respect to such Distribution Date.

            Class B Interest Percentage: With respect to any Distribution Date
and any Class of Class B Certificates, the percentage calculated by dividing the
Interest Accrual Amount of such Class (determined without regard to clause (ii)
of the definition thereof) by the Class B Interest Accrual Amount (determined
without regard to clause (ii) of the definition of each Interest Accrual
Amount).

            Class B Interest Shortfall Amount: Any of the Class B-1 Interest
Shortfall Amount, Class B-2 Interest Shortfall Amount, Class B-3 Interest
Shortfall Amount, Class B-4 Interest Shortfall Amount, Class B-5 Interest
Shortfall Amount or Class B-6 Interest Shortfall Amount.

            Class B Loss Percentage: With respect to any Determination Date and
any Class of Class B Certificates then outstanding, the percentage calculated by
dividing the Principal Balance of such Class B Certificates by the Class B
Principal Balance (determined without regard to any Principal Balance of any
Class of Class B Certificates not then outstanding), in each case determined as
of the preceding Determination Date.

            Class B Optimal Principal Amount: Any of the Class B-1, Class B-2,
Class B-3, Class B-4, Class B-5 or Class B-6 Optimal Principal Amounts.

            Class B Pass-Through Rate: As to any Distribution Date, a per annum
rate equal to 6.000%.

            Class B Percentage: Any one of the Class B-1 Percentage, Class B-2
Percentage, Class B-3 Percentage, Class B-4 Percentage, Class B-5 Percentage or
Class B-6 Percentage.

            Class B Prepayment Percentage: Any of the Class B-1 Prepayment
Percentage, Class B-2 Prepayment Percentage, Class B-3 Prepayment Percentage,
Class B-4 Prepayment Percentage, Class B-5 Prepayment Percentage or Class B-6
Prepayment Percentage.

            Class B Principal Balance: As of any date, an amount equal to the
sum of the Class B-1 Principal Balance, Class B-2 Principal Balance, Class B-3
Principal Balance, Class B-4 Principal Balance, Class B-5 Principal Balance and
Class B-6 Principal Balance.

            Class B Unpaid Interest Shortfall: Any of the Class B-1 Unpaid
Interest Shortfall, Class B-2 Unpaid Interest Shortfall, Class B-3 Unpaid
Interest Shortfall, Class B-4 Unpaid Interest Shortfall, Class B-5 Unpaid
Interest Shortfall or Class B-6 Unpaid Interest Shortfall.

            Class B-1 Certificate: Any one of the Certificates executed by the
Paying Agent and countersigned by the Authenticating Agent in substantially the
form set forth in Exhibit B-1 and Exhibit C hereto.

            Class B-1 Certificateholder: The registered holder of a Class B-1
Certificate.

            Class B-1 Distribution Amount: As to any Distribution Date, any
amount distributable to the Holders of the Class B-1 Certificates pursuant to
Paragraphs fifth, sixth and seventh of Section 4.01(a).

            Class B-1 Interest Shortfall Amount: As to any Distribution Date,
any amount by which the Interest Accrual Amount of the Class B-1 Certificates
with respect to such Distribution Date exceeds the amount distributed in respect
of the Class B-1 Certificates on such Distribution Date pursuant to Paragraph
fifth of Section 4.01(a).

            Class B-1 Optimal Principal Amount: As to any Distribution Date, an
amount equal to the sum of (I) the sum, as to each Outstanding Mortgage Loan, of
the product of (x) the Non-PO Fraction with respect to such Mortgage Loan and
(y) the sum of:

            (i) the Class B-1 Percentage of the principal portion of the Monthly
      Payment due on the Due Date occurring in the month of such Distribution
      Date on such Mortgage Loan;

            (ii) the Class B-1 Prepayment Percentage of all Unscheduled
      Principal Receipts (other than Recoveries) that were received by a
      Servicer with respect to such Mortgage Loan during the Applicable
      Unscheduled Principal Receipt Period relating to such Distribution Date
      for each applicable type of Unscheduled Principal Receipt;

            (iii) the Class B-1 Prepayment Percentage of the Scheduled Principal
      Balance of such Mortgage Loan which, during the one month period ending on
      the day preceding the Determination Date for such Distribution Date, was
      repurchased by the Depositor pursuant to Section 2.02, 2.03 or 3.08; and

            (iv) the Class B-1 Percentage of the Substitution Principal Amount
      with respect to each Mortgage Loan for which a Mortgage Loan was
      substituted during the one month period ending on the day preceding the
      Determination Date for such Distribution Date, less the amount allocable
      to the principal portion of any unreimbursed Periodic Advances previously
      made by the applicable Servicer, the Master Servicer or the Trustee in
      respect of such Mortgage Loan for which a Mortgage Loan was substituted;
      and

      (II) the Class B-1 Prepayment Percentage of the Non-PO Recovery for such
      Distribution Date;

provided, however, that if an Optimal Adjustment Event occurs with respect to
such Class and such Distribution Date, the Class B-1 Optimal Principal Amount
will equal the lesser of (A) the Class B-1 Optimal Principal Amount calculated
as described in the preceding provisions and (B) the Adjusted Principal Balance
for the Class B-1 Certificates.

            Class B-1 Percentage: As to any Distribution Date, the percentage
calculated by multiplying the Subordinated Percentage by either (i) if any Class
B Certificates (other than the Class B-1 Certificates) are eligible to receive
principal distributions for such Distribution Date in accordance with Section
4.01(d), a fraction, the numerator of which is the Class B-1 Principal Balance
(determined as of the Determination Date preceding such Distribution Date) and
the denominator of which is the sum of the Principal Balances of the Classes of
Class B Certificates eligible to receive principal distributions for such
Distribution Date in accordance with the provisions of Section 4.01(d) or (ii)
except as set forth in Section 4.01(d)(ii), in the event that the Class B
Certificates (other than the Class B-1 Certificates) are not eligible to receive
distributions of principal in accordance with Section 4.01(d)(i), one.

            Class B-1 Prepayment Percentage: As to any Distribution Date, the
percentage calculated by multiplying the Subordinated Prepayment Percentage by
either (i) if any Class B Certificates (other than the Class B-1 Certificates)
are eligible to receive principal distributions for such Distribution Date in
accordance with Section 4.01(d), a fraction, the numerator of which is the Class
B-1 Principal Balance (determined as of the Determination Date preceding such
Distribution Date) and the denominator of which is the sum of the Principal
Balances of the Classes of Class B Certificates eligible to receive principal
distributions for such Distribution Date in accordance with the provisions of
Section 4.01(d) or (ii) except as set forth in Section 4.01(d)(ii), in the event
that the Class B Certificates (other than the Class B-1 Certificates) are not
eligible to receive distributions of principal in accordance with Section
4.01(d)(i), one.

            Class B-1 Principal Balance: As to the first Determination Date, the
Original Class B-1 Principal Balance. As of any subsequent Determination Date,
the Original Class B-1 Principal Balance less the sum of all amounts previously
distributed in respect of the Class B-1 Certificates on prior Distribution Dates
(A) pursuant to Paragraph seventh of Section 4.01(a) (including any principal
otherwise payable to the Class B-1 Certificates used to pay any Class A-PO
Deferred Amounts) and (B) as a result of a Principal Adjustment; provided,
however, if the Class B-1 Certificates are the most subordinate Certificates
outstanding, the Class B-1 Principal Balance will equal the difference, if any,
between the Adjusted Pool Amount (Non-PO Portion) as of the preceding
Distribution Date less the Class A Non-PO Principal Balance as of such
Determination Date.

            Class B-1 Unpaid Interest Shortfall: As to any Distribution Date,
the amount, if any, by which the aggregate of the Class B-1 Interest Shortfall
Amounts for prior Distribution Dates is in excess of the amounts distributed in
respect of the Class B-1 Certificates on prior Distribution Dates pursuant to
Paragraph sixth of Section 4.01(a).

            Class B-2 Certificate: Any one of the Certificates executed by the
Paying Agent and countersigned by the Authenticating Agent in substantially the
form set forth in Exhibit B-2 and Exhibit C hereto.

            Class B-2 Certificateholder: The registered holder of a Class B-2
Certificate.

            Class B-2 Distribution Amount: As to any Distribution Date, any
amount distributable to the Holders of the Class B-2 Certificates pursuant to
Paragraphs eighth, ninth and tenth of Section 4.01(a).

            Class B-2 Interest Shortfall Amount: As to any Distribution Date,
any amount by which the Interest Accrual Amount of the Class B-2 Certificates
with respect to such Distribution Date exceeds the amount distributed in respect
of the Class B-2 Certificates on such Distribution Date pursuant to Paragraph
eighth of Section 4.01(a).

            Class B-2 Optimal Principal Amount: As to any Distribution Date, an
amount equal to the sum of (I) the sum, as to each Outstanding Mortgage Loan, of
the product of (x) the Non-PO Fraction with respect to such Mortgage Loan and
(y) the sum of:

            (i) the Class B-2 Percentage of the principal portion of the Monthly
      Payment due on the Due Date occurring in the month of such Distribution
      Date on such Mortgage Loan;

            (ii) the Class B-2 Prepayment Percentage of all Unscheduled
      Principal Receipts (other than Recoveries) that were received by a
      Servicer with respect to such Mortgage Loan during the Applicable
      Unscheduled Principal Receipt Period relating to such Distribution Date
      for each applicable type of Unscheduled Principal Receipt;

            (iii) the Class B-2 Prepayment Percentage of the Scheduled Principal
      Balance of such Mortgage Loan which, during the one month period ending on
      the day preceding the Determination Date for such Distribution Date, was
      repurchased by the Depositor pursuant to Section 2.02, 2.03 or 3.08; and

            (iv) the Class B-2 Percentage of the Substitution Principal Amount
      with respect to each Mortgage Loan for which a Mortgage Loan was
      substituted during the one month period ending on the day preceding the
      Determination Date for such Distribution Date, less the amount allocable
      to the principal portion of any unreimbursed Periodic Advances previously
      made by the applicable Servicer, the Master Servicer or the Trustee in
      respect of such Mortgage Loan for which a Mortgage Loan was substituted;
      and

      (II) the Class B-2 Prepayment Percentage of the Non-PO Recovery for such
      Distribution Date;

provided, however, that if an Optimal Adjustment Event occurs with respect to
such Class and such Distribution Date, the Class B-2 Optimal Principal Amount
will equal the lesser of (A) the Class B-2 Optimal Principal Amount calculated
as described in the preceding provisions and (B) the Adjusted Principal Balance
for the Class B-2 Certificates.

            Class B-2 Percentage: As to any Distribution Date, except as set
forth in the next sentence, the percentage calculated by multiplying (i) the
Subordinated Percentage by (ii) a fraction, the numerator of which is the Class
B-2 Principal Balance (determined as of the Determination Date preceding such
Distribution Date) and the denominator of which is the sum of the Principal
Balances of the Classes of Class B Certificates eligible to receive principal
distributions for such Distribution Date in accordance with the provisions of
Section 4.01(d). Except as set forth in Section 4.01(d)(ii), in the event that
the Class B-2 Certificates are not eligible to receive distributions of
principal in accordance with Section 4.01(d)(i), the Class B-2 Percentage for
such Distribution Date will be zero.

            Class B-2 Prepayment Percentage: As to any Distribution Date, except
as set forth in the next sentence, the percentage calculated by multiplying (i)
the Subordinated Prepayment Percentage by (ii) a fraction, the numerator of
which is the Class B-2 Principal Balance (determined as of the Determination
Date preceding such Distribution Date) and the denominator of which is the sum
of the Principal Balances of the Classes of Class B Certificates eligible to
receive principal distributions for such Distribution Date in accordance with
the provisions of Section 4.01(d). Except as set forth in Section 4.01(d)(ii),
in the event that the Class B-2 Certificates are not eligible to receive
distributions of principal in accordance with Section 4.01(d)(i), the Class B-2
Prepayment Percentage for such Distribution Date will be zero.

            Class B-2 Principal Balance: As to the first Determination Date, the
Original Class B-2 Principal Balance. As of any subsequent Determination Date,
the Original Class B-2 Principal Balance less the sum of all amounts previously
distributed in respect of the Class B-2 Certificates on prior Distribution Dates
(A) pursuant to Paragraph tenth of Section 4.01(a) (including any principal
otherwise payable to the Class B-2 Certificates used to pay any Class A-PO
Deferred Amounts) and (B) as a result of a Principal Adjustment; provided,
however, if the Class B-2 Certificates are the most subordinate Certificates
outstanding, the Class B-2 Principal Balance will equal the difference, if any,
between the Adjusted Pool Amount (Non-PO Portion) as of the preceding
Distribution Date less the sum of the Class A Non-PO Principal Balance and the
Class B-1 Principal Balance as of such Determination Date.

            Class B-2 Unpaid Interest Shortfall: As to any Distribution Date,
the amount, if any, by which the aggregate of the Class B-2 Interest Shortfall
Amounts for prior Distribution Dates is in excess of the amounts distributed in
respect of the Class B-2 Certificates on prior Distribution Dates pursuant to
Paragraph ninth of Section 4.01(a).

            Class B-3 Certificate: Any one of the Certificates executed by the
Paying Agent and countersigned by the Authenticating Agent in substantially the
form set forth in Exhibit B-3 and Exhibit C hereto.

            Class B-3 Certificateholder: The registered holder of a Class B-3
Certificate.

            Class B-3 Distribution Amount: As to any Distribution Date, any
amount distributable to the Holders of the Class B-3 Certificates pursuant to
Paragraphs eleventh, twelfth and thirteenth of Section 4.01(a).

            Class B-3 Interest Shortfall Amount: As to any Distribution Date,
any amount by which the Interest Accrual Amount of the Class B-3 Certificates
with respect to such Distribution Date exceeds the amount distributed in respect
of the Class B-3 Certificates on such Distribution Date pursuant to Paragraph
eleventh of Section 4.01(a).

            Class B-3 Optimal Principal Amount: As to any Distribution Date, an
amount equal to the sum of (I) the sum, as to each Outstanding Mortgage Loan, of
the product of (x) the Non-PO Fraction with respect to such Mortgage Loan and
(y) the sum of:

            (i) the Class B-3 Percentage of the principal portion of the Monthly
      Payment due on the Due Date occurring in the month of such Distribution
      Date on such Mortgage Loan;

            (ii) the Class B-3 Prepayment Percentage of all Unscheduled
      Principal Receipts (other than Recoveries) that were received by a
      Servicer with respect to such Mortgage Loan during the Applicable
      Unscheduled Principal Receipt Period relating to such Distribution Date
      for each applicable type of Unscheduled Principal Receipt;

            (iii) the Class B-3 Prepayment Percentage of the Scheduled Principal
      Balance of such Mortgage Loan which, during the one month period ending on
      the day preceding the Determination Date for such Distribution Date, was
      repurchased by the Depositor pursuant to Section 2.02, 2.03 or 3.08; and

            (iv) the Class B-3 Percentage of the Substitution Principal Amount
      with respect to each Mortgage Loan for which a Mortgage Loan was
      substituted during the one month period ending on the day preceding the
      Determination Date for such Distribution Date, less the amount allocable
      to the principal portion of any unreimbursed Periodic Advances previously
      made by the applicable Servicer, the Master Servicer or the Trustee in
      respect of such Mortgage Loan for which a Mortgage Loan was substituted;
      and

      (II) the Class B-3 Prepayment Percentage of the Non-PO Recovery for such
      Distribution Date;

provided, however, that if an Optimal Adjustment Event occurs with respect to
such Class and such Distribution Date, the Class B-3 Optimal Principal Amount
will equal the lesser of (A) the Class B-3 Optimal Principal Amount calculated
as described in the preceding provisions and (B) the Adjusted Principal Balance
for the Class B-3 Certificates.

            Class B-3 Percentage: As to any Distribution Date, except as set
forth in the next sentence, the percentage calculated by multiplying (i) the
Subordinated Percentage by (ii) a fraction, the numerator of which is the Class
B-3 Principal Balance (determined as of the Determination Date preceding such
Distribution Date) and the denominator of which is the sum of the Principal
Balances of the Classes of Class B Certificates eligible to receive principal
distributions for such Distribution Date in accordance with the provisions of
Section 4.01(d). Except as set forth in Section 4.01(d)(ii), in the event that
the Class B-3 Certificates are not eligible to receive distributions of
principal in accordance with Section 4.01(d)(i), the Class B-3 Percentage for
such Distribution Date will be zero.

            Class B-3 Prepayment Percentage: As to any Distribution Date, except
as set forth in the next sentence, the percentage calculated by multiplying (i)
the Subordinated Prepayment Percentage by (ii) a fraction, the numerator of
which is the Class B-3 Principal Balance (determined as of the Determination
Date preceding such Distribution Date) and the denominator of which is the sum
of the Principal Balances of the Classes of Class B Certificates eligible to
receive principal distributions for such Distribution Date in accordance with
the provisions of Section 4.01(d). Except as set forth in Section 4.01(d)(ii),
in the event that the Class B-3 Certificates are not eligible to receive
distributions of principal in accordance with Section 4.01(d)(i), the Class B-3
Prepayment Percentage for such Distribution Date will be zero.

            Class B-3 Principal Balance: As to the first Determination Date, the
Original Class B-3 Principal Balance. As of any subsequent Determination Date,
the Original Class B-3 Principal Balance less the sum of all amounts previously
distributed in respect of the Class B-3 Certificates on prior Distribution Dates
(A) pursuant to Paragraph thirteenth of Section 4.01(a) (including any principal
otherwise payable to the Class B-3 Certificates used to pay any Class A-PO
Deferred Amounts) and (B) as a result of a Principal Adjustment; provided,
however, if the Class B-3 Certificates are the most subordinate Certificates
outstanding, the Class B-3 Principal Balance will equal the difference, if any,
between the Adjusted Pool Amount (Non-PO Portion) as of the preceding
Distribution Date less the sum of the Class A Non-PO Principal Balance, the
Class B-1 Principal Balance and the Class B-2 Principal Balance as of such
Determination Date.

            Class B-3 Unpaid Interest Shortfall: As to any Distribution Date,
the amount, if any, by which the aggregate of the Class B-3 Interest Shortfall
Amounts for prior Distribution Dates is in excess of the amounts distributed in
respect of the Class B-3 Certificates on prior Distribution Dates pursuant to
Paragraph twelfth of Section 4.01(a).

            Class B-4 Certificate: Any one of the Certificates executed by the
Paying Agent and countersigned by the Authenticating Agent in substantially the
form set forth in Exhibit B-4 and Exhibit C hereto.

            Class B-4 Certificateholder: The registered holder of a Class B-4
Certificate.

            Class B-4 Distribution Amount: As to any Distribution Date, any
amount distributable to the Holders of the Class B-4 Certificates pursuant to
Paragraphs fourteenth, fifteenth and sixteenth of Section 4.01(a).

            Class B-4 Interest Shortfall Amount: As to any Distribution Date,
any amount by which the Interest Accrual Amount of the Class B-4 Certificates
with respect to such Distribution Date exceeds the amount distributed in respect
of the Class B-4 Certificates on such Distribution Date pursuant to Paragraph
fourteenth of Section 4.01(a).

            Class B-4 Optimal Principal Amount: As to any Distribution Date, an
amount equal to the sum of (I) the sum, as to each Outstanding Mortgage Loan, of
the product of (x) the Non-PO Fraction with respect to such Mortgage Loan and
(y) the sum of:

            (i) the Class B-4 Percentage of the principal portion of the Monthly
      Payment due on the Due Date occurring in the month of such Distribution
      Date on such Mortgage Loan;

            (ii) the Class B-4 Prepayment Percentage of all Unscheduled
      Principal Receipts (other than Recoveries) that were received by a
      Servicer with respect to such Mortgage Loan during the Applicable
      Unscheduled Principal Receipt Period relating to such Distribution Date
      for each applicable type of Unscheduled Principal Receipt;

            (iii) the Class B-4 Prepayment Percentage of the Scheduled Principal
      Balance of such Mortgage Loan which, during the one month period ending on
      the day preceding the Determination Date for such Distribution Date, was
      repurchased by the Depositor pursuant to Section 2.02, 2.03 or 3.08; and

            (iv) the Class B-4 Percentage of the Substitution Principal Amount
      with respect to each Mortgage Loan for which a Mortgage Loan was
      substituted during the one month period ending on the day preceding the
      Determination Date for such Distribution Date, less the amount allocable
      to the principal portion of any unreimbursed Periodic Advances previously
      made by the applicable Servicer, the Master Servicer or the Trustee in
      respect of such Mortgage Loan for which a Mortgage Loan was substituted;
      and

      (II) the Class B-4 Prepayment Percentage of the Non-PO Recovery for such
      Distribution Date;

provided, however, that if an Optimal Adjustment Event occurs with respect to
such Class and such Distribution Date, the Class B-4 Optimal Principal Amount
will equal the lesser of (A) the Class B-4 Optimal Principal Amount calculated
as described in the preceding provisions and (B) the Adjusted Principal Balance
for the Class B-4 Certificates.

            Class B-4 Percentage: As to any Distribution Date, except as set
forth in the next sentence, the percentage calculated by multiplying (i) the
Subordinated Percentage by (ii) a fraction, the numerator of which is the Class
B-4 Principal Balance (determined as of the Determination Date preceding such
Distribution Date) and the denominator of which is the sum of the Principal
Balances of the Classes of Class B Certificates eligible to receive principal
distributions for such Distribution Date in accordance with the provisions of
Section 4.01(d). Except as set forth in Section 4.01(d)(ii), in the event that
the Class B-4 Certificates are not eligible to receive distributions of
principal in accordance with Section 4.01(d)(i), the Class B-4 Percentage for
such Distribution Date will be zero.

            Class B-4 Prepayment Percentage: As to any Distribution Date, except
as set forth in the next sentence, the percentage calculated by multiplying (i)
the Subordinated Prepayment Percentage by (ii) a fraction, the numerator of
which is the Class B-4 Principal Balance (determined as of the Determination
Date preceding such Distribution Date) and the denominator of which is the sum
of the Principal Balances of the Classes of Class B Certificates eligible to
receive principal distributions for such Distribution Date in accordance with
the provisions of Section 4.01(d). Except as set forth in Section 4.01(d)(ii),
in the event that the Class B-4 Certificates are not eligible to receive
distributions of principal in accordance with Section 4.01(d)(i), the Class B-4
Prepayment Percentage for such Distribution Date will be zero.

            Class B-4 Principal Balance: As to the first Determination Date, the
Original Class B-4 Principal Balance. As of any subsequent Determination Date,
the Original Class B-4 Principal Balance less the sum of all amounts previously
distributed in respect of the Class B-4 Certificates on prior Distribution Dates
(A) pursuant to Paragraph sixteenth of Section 4.01(a) (including any principal
otherwise payable to the Class B-4 Certificates used to pay any Class A-PO
Deferred Amounts) and (B) as a result of a Principal Adjustment; provided,
however, if the Class B-4 Certificates are the most subordinate Certificates
outstanding, the Class B-4 Principal Balance will equal the difference, if any,
between the Adjusted Pool Amount (Non-PO Portion) as of the preceding
Distribution Date less the sum of the Class A Non-PO Principal Balance, the
Class B-1 Principal Balance, the Class B-2 Principal Balance and the Class B-3
Principal Balance as of such Determination Date.

            Class B-4 Unpaid Interest Shortfall: As to any Distribution Date,
the amount, if any, by which the aggregate of the Class B-4 Interest Shortfall
Amounts for prior Distribution Dates is in excess of the amounts distributed in
respect of the Class B-4 Certificates on prior Distribution Dates pursuant to
Paragraph fifteenth of Section 4.01(a).

            Class B-5 Certificate: Any one of the Certificates executed by the
Paying Agent and countersigned by the Authenticating Agent in substantially the
form set forth in Exhibit B-5 and Exhibit C hereto.

            Class B-5 Certificateholder: The registered holder of a Class B-5
Certificate.

            Class B-5 Distribution Amount: As to any Distribution Date, any
amount distributable to the Holders of the Class B-5 Certificates pursuant to
Paragraphs seventeenth, eighteenth and nineteenth of Section 4.01(a).

            Class B-5 Interest Shortfall Amount: As to any Distribution Date,
any amount by which the Interest Accrual Amount of the Class B-5 Certificates
with respect to such Distribution Date exceeds the amount distributed in respect
of the Class B-5 Certificates on such Distribution Date pursuant to Paragraph
seventeenth of Section 4.01(a).

            Class B-5 Optimal Principal Amount: As to any Distribution Date, an
amount equal to the sum of (I) the sum, as to each Outstanding Mortgage Loan, of
the product of (x) the Non-PO Fraction with respect to such Mortgage Loan and
(y) the sum of:

            (i) the Class B-5 Percentage of the principal portion of the Monthly
      Payment due on the Due Date occurring in the month of such Distribution
      Date on such Mortgage Loan;

            (ii) the Class B-5 Prepayment Percentage of all Unscheduled
      Principal Receipts (other than Recoveries) that were received by a
      Servicer with respect to such Mortgage Loan during the Applicable
      Unscheduled Principal Receipt Period relating to such Distribution Date
      for each applicable type of Unscheduled Principal Receipt;

            (iii) the Class B-5 Prepayment Percentage of the Scheduled Principal
      Balance of such Mortgage Loan which, during the one month period ending on
      the day preceding the Determination Date for such Distribution Date, was
      repurchased by the Depositor pursuant to Section 2.02, 2.03 or 3.08; and

            (iv) the Class B-5 Percentage of the Substitution Principal Amount
      with respect to each Mortgage Loan for which a Mortgage Loan was
      substituted during the one month period ending on the day preceding the
      Determination Date for such Distribution Date, less the amount allocable
      to the principal portion of any unreimbursed Periodic Advances previously
      made by the applicable Servicer, the Master Servicer or the Trustee in
      respect of such Mortgage Loan for which a Mortgage Loan was substituted;
      and

      (II) the Class B-5 Prepayment Percentage of the Non-PO Recovery for such
      Distribution Date;

provided, however, that if an Optimal Adjustment Event occurs with respect to
such Class and such Distribution Date, the Class B-5 Optimal Principal Amount
will equal the lesser of (A) the Class B-5 Optimal Principal Amount calculated
as described in the preceding provisions and (B) the Adjusted Principal Balance
for the Class B-5 Certificates.

            Class B-5 Percentage: As to any Distribution Date, except as set
forth in the next sentence, the percentage calculated by multiplying (i) the
Subordinated Percentage by (ii) a fraction, the numerator of which is the Class
B-5 Principal Balance (determined as of the Determination Date preceding such
Distribution Date) and the denominator of which is the sum of the Principal
Balances of the Classes of Class B Certificates eligible to receive principal
distributions for such Distribution Date in accordance with the provisions of
Section 4.01(d). Except as set forth in Section 4.01(d)(ii), in the event that
the Class B-5 Certificates are not eligible to receive distributions of
principal in accordance with Section 4.01(d)(i), the Class B-5 Percentage for
such Distribution Date will be zero.

            Class B-5 Prepayment Percentage: As to any Distribution Date, except
as set forth in the next sentence, the percentage calculated by multiplying (i)
the Subordinated Prepayment Percentage by (ii) a fraction, the numerator of
which is the Class B-5 Principal Balance (determined as of the Determination
Date preceding such Distribution Date) and the denominator of which is the sum
of the Principal Balances of the Classes of Class B Certificates eligible to
receive principal distributions for such Distribution Date in accordance with
the provisions of Section 4.01(d). Except as set forth in Section 4.01(d)(ii),
in the event that the Class B-5 Certificates are not eligible to receive
distributions of principal in accordance with Section 4.01(d)(i), the Class B-5
Prepayment Percentage for such Distribution Date will be zero.

            Class B-5 Principal Balance: As to the first Determination Date, the
Original Class B-5 Principal Balance. As of any subsequent Determination Date,
the Original Class B-5 Principal Balance less the sum of all amounts previously
distributed in respect of the Class B-5 Certificates on prior Distribution Dates
(A) pursuant to Paragraph nineteenth of Section 4.01(a) (including any principal
otherwise payable to the Class B-5 Certificates used to pay any Class A-PO
Deferred Amounts) and (B) as a result of a Principal Adjustment; provided,
however, if the Class B-5 Certificates are the most subordinate Certificates
outstanding, the Class B-5 Principal Balance will equal the difference, if any,
between the Adjusted Pool Amount (Non-PO Portion) as of the preceding
Distribution Date less the sum of the Class A Non-PO Principal Balance, the
Class B-1 Principal Balance, the Class B-2 Principal Balance, the Class B-3
Principal Balance and the Class B-4 Principal Balance as of such Determination
Date.

            Class B-5 Unpaid Interest Shortfall: As to any Distribution Date,
the amount, if any, by which the aggregate of the Class B-5 Interest Shortfall
Amounts for prior Distribution Dates is in excess of the amounts distributed in
respect of the Class B-5 Certificates on prior Distribution Dates pursuant to
Paragraph eighteenth of Section 4.01(a).

            Class B-6 Certificate: Any one of the Certificates executed by the
Paying Agent and countersigned by the Authenticating Agent in substantially the
form set forth in Exhibit B-6 and Exhibit C hereto.

            Class B-6 Certificateholder: The registered holder of a Class B-6
Certificate.

            Class B-6 Distribution Amount: As to any Distribution Date, any
amount distributable to the Holders of the Class B-6 Certificates pursuant to
Paragraphs twentieth, twenty-first and twenty-second of Section 4.01(a).

            Class B-6 Interest Shortfall Amount: As to any Distribution Date,
any amount by which the Interest Accrual Amount of the Class B-6 Certificates
with respect to such Distribution Date exceeds the amount distributed in respect
of the Class B-6 Certificates on such Distribution Date pursuant to Paragraph
twentieth of Section 4.01(a).

            Class B-6 Optimal Principal Amount: As to any Distribution Date, an
amount equal to the sum of (I) the sum, as to each Outstanding Mortgage Loan, of
the product of (x) the Non-PO Fraction with respect to such Mortgage Loan and
(y) the sum of:

            (i) the Class B-6 Percentage of the principal portion of the Monthly
      Payment due on the Due Date occurring in the month of such Distribution
      Date on such Mortgage Loan;

            (ii) the Class B-6 Prepayment Percentage of all Unscheduled
      Principal Receipts (other than Recoveries) that were received by a
      Servicer with respect to such Mortgage Loan during the Applicable
      Unscheduled Principal Receipt Period relating to such Distribution Date
      for each applicable type of Unscheduled Principal Receipt;

            (iii) the Class B-6 Prepayment Percentage of the Scheduled Principal
      Balance of such Mortgage Loan which, during the one month period ending on
      the day preceding the Determination Date for such Distribution Date, was
      repurchased by the Depositor pursuant to Section 2.02, 2.03 or 3.08; and

            (iv) the Class B-6 Percentage of the Substitution Principal Amount
      with respect to each Mortgage Loan for which a Mortgage Loan was
      substituted during the one month period ending on the day preceding the
      Determination Date for such Distribution Date, less the amount allocable
      to the principal portion of any unreimbursed Periodic Advances previously
      made by the applicable Servicer, the Master Servicer or the Trustee in
      respect of such Mortgage Loan for which a Mortgage Loan was substituted;
      and

      (II) the Class B-6 Prepayment Percentage of the Non-PO Recovery for such
      Distribution Date;

provided, however, that if an Optimal Adjustment Event occurs with respect to
such Class and such Distribution Date, the Class B-6 Optimal Principal Amount
will equal the lesser of (A) the Class B-6 Optimal Principal Amount calculated
as described in the preceding provisions and (B) the Adjusted Principal Balance
for the Class B-6 Certificates.

            Class B-6 Percentage: As to any Distribution Date, except as set
forth in the next sentence, the percentage calculated by multiplying (i) the
Subordinated Percentage by (ii) a fraction, the numerator of which is the Class
B-6 Principal Balance (determined as of the Determination Date preceding such
Distribution Date) and the denominator of which is the sum of the Principal
Balances of the Classes of Class B Certificates eligible to receive principal
distributions for such Distribution Date in accordance with the provisions of
Section 4.01(d). Except as set forth in Section 4.01(d)(ii), in the event that
the Class B-6 Certificates are not eligible to receive distributions of
principal in accordance with Section 4.01(d)(i), the Class B-6 Percentage for
such Distribution Date will be zero.

            Class B-6 Prepayment Percentage: As to any Distribution Date, except
as set forth in the next sentence, the percentage calculated by multiplying (i)
the Subordinated Prepayment Percentage by (ii) a fraction, the numerator of
which is the Class B-6 Principal Balance (determined as of the Determination
Date preceding such Distribution Date) and the denominator of which is the sum
of the Principal Balances of the Classes of Class B Certificates eligible to
receive principal distributions for such Distribution Date in accordance with
the provisions of Section 4.01(d). Except as set forth in Section 4.01(d)(ii),
in the event that the Class B-6 Certificates are not eligible to receive
distributions of principal in accordance with Section 4.01(d)(i), the Class B-6
Prepayment Percentage for such Distribution Date will be zero.

            Class B-6 Principal Balance: As to the first Determination Date, the
Original Class B-6 Principal Balance. As of any subsequent Determination Date,
for so long as the Class B-6 Certificates are outstanding, the difference, if
any, between the Adjusted Pool Amount (Non-PO Portion) as of the preceding
Distribution Date less the sum of the Class A Non-PO Principal Balance, the
Class B-1 Principal Balance, the Class B-2 Principal Balance, the Class B-3
Principal Balance, the Class B-4 Principal Balance and the Class B-5 Principal
Balance as of such Determination Date.

            Class B-6 Unpaid Interest Shortfall: As to any Distribution Date,
the amount, if any, by which the aggregate of the Class B-6 Interest Shortfall
Amounts for prior Distribution Dates is in excess of the amounts distributed in
respect of the Class B-6 Certificates on prior Distribution Dates pursuant to
Paragraph twenty-first of Section 4.01(a).

            Class B-L1 Interest: A regular interest in the Lower-Tier REMIC
which is held as an asset of the Upper-Tier REMIC and is entitled to monthly
distributions as provided in Section 4.01(a) hereof.

            Class B-L2 Interest: A regular interest in the Lower-Tier REMIC
which is held as an asset of the Upper-Tier REMIC and is entitled to monthly
distributions as provided in Section 4.01(a) hereof.

            Class B-L3 Interest: A regular interest in the Lower-Tier REMIC
which is held as an asset of the Upper-Tier REMIC and is entitled to monthly
distributions as provided in Section 4.01(a) hereof.

            Class B-L4 Interest: A regular interest in the Lower-Tier REMIC
which is held as an asset of the Upper-Tier REMIC and is entitled to monthly
distributions as provided in Section 4.01(a) hereof.

            Class B-L5 Interest: A regular interest in the Lower-Tier REMIC
which is held as an asset of the Upper-Tier REMIC and is entitled to monthly
distributions as provided in Section 4.01(a) hereof.

            Class B-L6 Interest: A regular interest in the Lower-Tier REMIC
which is held as an asset of the Upper-Tier REMIC and is entitled to monthly
distributions as provided in Section 4.01(a) hereof.

            Clearing Agency: An organization registered as a "clearing agency"
pursuant to Section 17A of the Exchange Act. The initial Clearing Agency shall
be The Depository Trust Company.

            Clearing Agency Participant: A broker, dealer, bank, financial
institution or other Person for whom a Clearing Agency effects book-entry
transfers of securities deposited with the Clearing Agency.

            Closing Date: The date of initial issuance of the Certificates, as
set forth in Section 11.20.

            Code: The Internal Revenue Code of 1986, as it may be amended from
time to time, any successor statutes thereto, and applicable U.S. Department of
the Treasury temporary or final regulations promulgated thereunder.

            Commission: The United States Securities and Exchange Commission.

            Compensating Interest: With respect to any Distribution Date, the
least of (a) the aggregate Prepayment Interest Shortfall on the Mortgage Loans
for such Distribution Date, (b) the product of (i) 1/12th of 0.20% and (ii) the
Pool Scheduled Principal Balance for such Distribution Date and (c) the
Available Master Servicing Compensation for such Distribution Date.

            Co-op Shares: Shares issued by private non-profit housing
corporations.

            Corporate Trust Office: With respect to (a) the Trustee, the office
of the Trustee at which at any particular time its duties under this Agreement
shall be administered, which office, at the date of the execution of this
instrument, is located at 452 Fifth Avenue, New York, New York 10018, Attention:
CTLA - Structured Finance, WFMBS 2007-4 and (b) the Paying Agent, Certificate
Registrar and Authenticating Agent, for Certificate transfer purposes at Wells
Fargo Center, Sixth Street and Marquette Avenue, Minneapolis, Minnesota 55479
Attn: Corporate Trust Services--WFMBS 2007-4, and for all other purposes at 9062
Old Annapolis Road, Columbia, Maryland 21045 Attn: Corporate Trust
Services--WFMBS 2007-4.

            Corresponding Upper-Tier Class or Classes: As to the following
Uncertificated Lower-Tier Interests, the Corresponding Upper-Tier Class or
Classes as follows:

 Uncertificated Lower-Tier Interest   Corresponding Upper-Tier Class or Classes
 ----------------------------------   -----------------------------------------
 Class A-L1 Interest                  Class A-1, Class A-2, Class A-3, Class
                                      A-4, Class A-6, Class A-8, Class A-9,
                                      Class A-10, Class A-12, Class A-13, Class
                                      A-14 and Class A-15 Certificates

 Class A-L5 Interest                  Class A-5 Certificates

 Class A-L7 Interest                  Class A-7 and Class A-11 Certificates

 Class A-L16 Interest                 Class A-16, Class A-17, Class A-18, Class
                                      A-19, Class A-20 and Class A-21
                                      Certificates

 Class A-LPO Interest                 Class A-PO Certificates

 Class A-LUR Interest                 Class A-R Certificate

 Class B-L1 Interest                  Class B-1 Certificates

 Class B-L2 Interest                  Class B-2 Certificates

 Class B-L3 Interest                  Class B-3 Certificates

 Class B-L4 Interest                  Class B-4 Certificates

 Class B-L5 Interest                  Class B-5 Certificates

 Class B-L6 Interest                  Class B-6 Certificates

            Counterparty: The Royal Bank of Scotland plc.

            Current Class A Interest Distribution Amount: As to any Distribution
Date, the amount distributed in respect of the Classes of Class A Certificates
pursuant to Paragraph first of Section 4.01(a) on such Distribution Date.

            Current Class B Interest Distribution Amount: As to any Distribution
Date, the amount distributed in respect of the Classes of Class B Certificates
pursuant to Paragraphs fifth, eighth, eleventh, fourteenth, seventeenth and
twentieth of Section 4.01(a) on such Distribution Date.

            Current Class B-1 Fractional Interest: As to any Distribution Date
subsequent to the first Distribution Date, the percentage obtained by dividing
the sum of the Principal Balances of the Class B-2, Class B-3, Class B-4, Class
B-5 and Class B-6 Certificates by the Aggregate Non-PO Principal Balance. As to
the first Distribution Date, the Original Class B-1 Fractional Interest.

            Current Class B-2 Fractional Interest: As to any Distribution Date
subsequent to the first Distribution Date, the percentage obtained by dividing
the sum of the Principal Balances of the Class B-3, Class B-4, Class B-5 and
Class B-6 Certificates by the Aggregate Non-PO Principal Balance. As to the
first Distribution Date, the Original Class B-2 Fractional Interest.

            Current Class B-3 Fractional Interest: As to any Distribution Date
subsequent to the first Distribution Date, the percentage obtained by dividing
the sum of the Principal Balances of the Class B-4, Class B-5 and Class B-6
Certificates by the Aggregate Non-PO Principal Balance. As to the first
Distribution Date, the Original Class B-3 Fractional Interest.

            Current Class B-4 Fractional Interest: As to any Distribution Date
subsequent to the first Distribution Date, the percentage obtained by dividing
the sum of the Principal Balances of the Class B-5 and Class B-6 Certificates by
the Aggregate Non-PO Principal Balance. As to the first Distribution Date, the
Original Class B-4 Fractional Interest.

            Current Class B-5 Fractional Interest: As to any Distribution Date
subsequent to the first Distribution Date, the percentage obtained by dividing
the Principal Balance of the Class B-6 Certificates by the Aggregate Non-PO
Principal Balance. As to the first Distribution Date, the Original Class B-5
Fractional Interest.

            Curtailment: Any Principal Prepayment made by a Mortgagor which is
not a Prepayment in Full.

            Curtailment Interest Shortfall: On any Distribution Date with
respect to a Mortgage Loan which was the subject of a Curtailment:

            (A)   in the case where the Applicable Unscheduled Principal Receipt
                  Period is the Mid-Month Receipt Period and such Curtailment is
                  received by the applicable Servicer on or after the
                  Determination Date in the month preceding the month of such
                  Distribution Date but prior to the first day of the month of
                  such Distribution Date, the amount of interest that would have
                  accrued at the Net Mortgage Interest Rate on the amount of
                  such Curtailment from the day of its receipt or, if earlier,
                  its application by such Servicer through the last day of the
                  month preceding the month of such Distribution Date; and

            (B)   in the case where the Applicable Unscheduled Principal Receipt
                  Period is the Prior Month Receipt Period and such Curtailment
                  is received by the applicable Servicer during the month
                  preceding the month of such Distribution Date, the amount of
                  interest that would have accrued at the Net Mortgage Interest
                  Rate on the amount of such Curtailment from the day of its
                  receipt or, if earlier, its application by such Servicer
                  through the last day of the month in which such Curtailment is
                  received.

            CUSIP Number: With respect to each Certificate, the identification
number provided by the CUSIP Service Bureau and appearing on the face of such
Certificate.

            Custodial Agreement: The Custodial Agreement, dated as of March 28,
2007, among the Custodian, the Depositor, the Master Servicer and the Trustee,
which agreement is attached hereto as Exhibit E, as the same may be amended or
modified from time to time in accordance with the terms thereof.

            Custodial P&I Account: The Custodial P&I Account, as defined in each
of the Servicing Agreements, with respect to the Mortgage Loans. In determining
whether the Custodial P&I Account under any Servicing Agreement is "acceptable"
to the Master Servicer (as may be required by the definition of "Eligible
Account" contained in the Servicing Agreements), the Master Servicer shall
require that any such account shall be acceptable to each of the Rating
Agencies.

            Custodian: Wells Fargo Bank, or its successor in interest under the
Custodial Agreement. Initially, the custodial functions shall be performed by
the Corporate Trust Services division of Wells Fargo Bank.

            Cut-Off Date: The first day of the month of initial issuance of the
Certificates as set forth in Section 11.01.

            Cut-Off Date Aggregate Principal Balance: The aggregate of the
Cut-Off Date Principal Balances of the Mortgage Loans as set forth in Section
11.02.

            Cut-Off Date Principal Balance: As to each Mortgage Loan, its unpaid
principal balance as of the close of business on the Cut-Off Date (but without
giving effect to any Unscheduled Principal Receipts received or applied on the
Cut-Off Date), reduced by all payments of principal due on or before the Cut-Off
Date and not paid, and increased by scheduled monthly payments of principal due
after the Cut-Off Date but received by the related Servicer on or before the
Cut-Off Date.

            Debt Service Reduction: With respect to any Mortgage Loan, a
reduction in the scheduled Monthly Payment for such Mortgage Loan by a court of
competent jurisdiction in a proceeding under the Bankruptcy Code, except such a
reduction constituting a Deficient Valuation.

            Deficient Valuation: With respect to any Mortgage Loan, a valuation
by a court of competent jurisdiction of the Mortgaged Property in an amount less
than the then-outstanding indebtedness under the Mortgage Loan, or any reduction
in the amount of principal to be paid in connection with any scheduled Monthly
Payment that results in a permanent forgiveness of principal, which valuation or
reduction results from a proceeding under the Bankruptcy Code.

            Definitive Certificates: As defined in Section 5.01(b).

            Denomination: The amount, if any, specified on the face of each
Certificate (other than the Interest Only Certificates) representing the
principal portion of the Cut-Off Date Aggregate Principal Balance evidenced by
such Certificate. As to the Interest Only Certificates, the amount specified on
the face of such Certificate representing the portion of the Original Notional
Amount.

            Depositor: Wells Fargo Asset Securities Corporation, or its
successor in interest.

            Determination Date: The 17th day of the month in which the related
Distribution Date occurs, or if such 17th day is not a Business Day, the
Business Day preceding such 17th day.

            Discount Mortgage Loan: A Mortgage Loan with a Net Mortgage Interest
Rate of less than 6.000%.

            Distribution Date: The 25th day of any month, beginning in the month
following the month of initial issuance of the Certificates, or if such 25th day
is not a Business Day, the Business Day following such 25th day.

            Distribution Date Statement: As defined in Section 4.04(a).

            Document Transfer Date: The 60th day following the occurrence of a
Document Transfer Event.

            Document Transfer Event: The occurrence of either of the following:
(i) Wells Fargo Bank is no longer the Servicer of any of the Mortgage Loans or
(ii) the senior, unsecured long-term debt rating of Wells Fargo & Company is
less than "BBB-" by Fitch.

            Due Date: With respect to any Mortgage Loan, the day of the month in
which the Monthly Payment on such Mortgage Loan is scheduled to be paid.

            Eligible Account: One or more accounts (i) that are maintained with
a depository institution (which may be the Master Servicer) whose long-term debt
obligations (or, in the case of a depository institution which is part of a
holding company structure, the long-term debt obligations of such parent holding
company) at the time of deposit therein are rated at least "AA" (or the
equivalent) by each Rating Agency, (ii) the deposits in which are fully insured
by the FDIC through either the Bank Insurance Fund or the Savings Association
Insurance Fund, (iii) the deposits in which are insured by the FDIC through
either the Bank Insurance Fund or the Savings Association Insurance Fund (to the
limit established by the FDIC) and the uninsured deposits in which accounts are
otherwise secured, as evidenced by an Opinion of Counsel delivered to the
Trustee, such that the Trustee, on behalf of the Certificateholders has a claim
with respect to the funds in such accounts or a perfected first security
interest against any collateral securing such funds that is superior to claims
of any other depositors or creditors of the depository institution with which
such accounts are maintained, (iv) that are trust accounts maintained with the
trust department of a federal or state chartered depository institution or trust
company acting in its fiduciary capacity or (v) such other account that is
acceptable to each of the Rating Agencies and would not cause the Trust Estate
to fail to qualify as two separate REMICs or result in the imposition of any
federal tax on either of the Upper-Tier REMIC or the Lower-Tier REMIC.

            Eligible Investments: At any time, any one or more of the following
obligations and securities which shall mature not later than the Business Day
preceding the Distribution Date next succeeding the date of such investment,
provided that such investments continue to qualify as "cash flow investments" as
defined in Code Section 860G(a)(6):

            (i) obligations of the United States of America or any agency
      thereof, provided such obligations are backed by the full faith and credit
      of the United States of America;

            (ii) general obligations of or obligations guaranteed by any state
      of the United States of America or the District of Columbia receiving the
      highest short-term or highest long-term rating of each Rating Agency, or
      such lower rating as would not result in the downgrading or withdrawal of
      the rating then assigned to any of the Certificates by any Rating Agency
      or result in any of such rated Certificates being placed on credit review
      status (other than for possible upgrading) by any Rating Agency;

            (iii) commercial or finance company paper which is then rated in the
      highest long-term commercial or finance company paper rating category of
      each Rating Agency or the highest short-term rating category of each
      Rating Agency, or such lower rating category as would not result in the
      downgrading or withdrawal of the rating then assigned to any of the
      Certificates by any Rating Agency or result in any of such rated
      Certificates being placed on credit review status (other than for possible
      upgrading) by any Rating Agency;

            (iv) certificates of deposit, demand or time deposits, federal funds
      or banker's acceptances issued by any depository institution or trust
      company incorporated under the laws of the United States or of any state
      thereof and subject to supervision and examination by federal and/or state
      banking authorities, provided that the commercial paper and/or debt
      obligations of such depository institution or trust company (or in the
      case of the principal depository institution in a holding company system,
      the commercial paper or debt obligations of such holding company) are then
      rated in the highest short-term or the highest long-term rating category
      for such securities of each of the Rating Agencies, or such lower rating
      categories as would not result in the downgrading or withdrawal of the
      rating then assigned to any of the Certificates by any Rating Agency or
      result in any of such rated Certificates being placed on credit review
      status (other than for possible upgrading) by any Rating Agency;

            (v) guaranteed reinvestment agreements issued by any bank, insurance
      company or other corporation acceptable to each Rating Agency at the time
      of the issuance of such agreements;

            (vi) repurchase agreements on obligations with respect to any
      security described in clauses (i) or (ii) above or any other security
      issued or guaranteed by an agency or instrumentality of the United States
      of America, in either case entered into with a depository institution or
      trust company (acting as principal) described in (iv) above;

            (vii) securities (other than stripped bonds or stripped coupon
      securities) bearing interest or sold at a discount issued by any
      corporation incorporated under the laws of the United States of America or
      any state thereof which, at the time of such investment or contractual
      commitment providing for such investment, are then rated in the highest
      short-term or the highest long-term rating category by each Rating Agency,
      or in such lower rating category as would not result in the downgrading or
      withdrawal of the rating then assigned to any of the Certificates by any
      Rating Agency or result in any of such rated Certificates being placed on
      credit review status (other than for possible upgrading) by any Rating
      Agency;

            (viii) such other investments acceptable to each Rating Agency as
      would not result in the downgrading of the rating then assigned to the
      Certificates by any Rating Agency or result in any of such rated
      Certificates being placed on credit review status (other than for possible
      upgrading) by any Rating Agency; and

            (ix) any mutual fund, money market fund, common trust fund or other
      pooled investment vehicle, the assets of which are limited to instruments
      that otherwise would constitute Eligible Investments hereunder, including
      any such fund that is managed by the Trustee or Master Servicer or any
      affiliate of the Trustee or Master Servicer or for which the Trustee or
      Master Servicer or any of its affiliates acts as an adviser as long as
      such fund is rated in at least the highest rating category by each Rating
      Agency rating such fund.

            In no event shall an instrument be an Eligible Investment if such
instrument evidences either (i) a right to receive only interest payments with
respect to the obligations underlying such instrument, or (ii) both principal
and interest payments derived from obligations underlying such instrument and
the interest and principal payments with respect to such instrument provide a
yield to maturity at the date of investment of greater than 120% of the yield to
maturity at par of such underlying obligations.

            ERISA: The Employee Retirement Income Security Act of 1974, as
amended.

            ERISA Prohibited Holder: As defined in Section 5.02(d).

            Errors and Omissions Policy: As defined in each of the Servicing
Agreements.

            Event of Default: Any of the events specified in Section 7.01.

            Excess Funds: With respect to the Reserve Fund and for any
Distribution Date, the amount by which (a) the Yield Maintenance Agreement
Payments for prior Distribution Dates exceed (b) the amount actually paid from
the Reserve Fund with respect to (i) Yield Maintenance Amounts for such prior
Distribution Dates and (ii) Yield Maintenance Amount Shortfalls for such prior
Distribution Dates.

            Exchange Act: The Securities Exchange Act of 1934, as amended.

            FDIC: The Federal Deposit Insurance Corporation or any successor
thereto.

            Fidelity Bond: As defined in each of the Servicing Agreements.

            Final Distribution Date: The Distribution Date on which the final
distribution in respect of the Certificates is made pursuant to Section 9.01.

            Final Scheduled Maturity Date: The Final Scheduled Maturity Date for
each Class of Class A Certificates and Class B Certificates is April 27, 2037,
which corresponds to the "latest possible maturity date" for purposes of Section
860G(a)(1) of the Internal Revenue Code of 1986, as amended.

            Fitch: Fitch Ratings, or its successor in interest.

            Fixed Retained Yield: The fixed percentage of interest on each
Mortgage Loan with a Mortgage Interest Rate greater than the sum of (a) 6.000%,
(b) the applicable Servicing Fee Rate and (c) the Master Servicing Fee Rate,
which will be determined on a loan by loan basis and will equal the Mortgage
Interest Rate on each Mortgage Loan minus the sum of the rates described in
clauses (a), (b) and (c), which is not assigned to and not part of the Trust
Estate.

            Fixed Retained Yield Rate: With respect to each Mortgage Loan, a per
annum rate equal to the greater of (a) zero and (b) the Mortgage Interest Rate
on such Mortgage Loan minus, the sum of (a) 6.000%, (b) the applicable Servicing
Fee Rate and (c) the Master Servicing Fee Rate.

            Form 8-K: A Current Report on Form 8-K under the Exchange Act.

            Form 8-K Disclosure Information: As defined in Section 3.12(c).

            Form 10-D: An Asset-Backed Issuer Distribution Report on Form 10-D
under the Exchange Act.

            Form 10-K: An Annual Report on Form 10-K under the Exchange Act.

            Form 15: A Form 15 Suspension Notification under the Exchange Act.

            Full Unscheduled Principal Receipt: Any Unscheduled Principal
Receipt with respect to a Mortgage Loan (i) in the amount of the outstanding
principal balance of such Mortgage Loan and resulting in the full satisfaction
of such Mortgage Loan or (ii) representing Liquidation Proceeds other than
Partial Liquidation Proceeds.

            Grantor Trust: That portion of the Trust exclusive of the REMICs
consisting of (a) the right of the Class A-5 Certificates to receive amounts
from the Reserve Fund and (b) the Yield Maintenance Agreement and the Reserve
Fund.

            Holder: See "Certificateholder."

            Independent: When used with respect to any specified Person, such
Person who (i) is in fact independent of the Depositor, the Master Servicer and
any Servicer, (ii) does not have any direct financial interest or any material
indirect financial interest in the Depositor or the Master Servicer or any
Servicer or in an affiliate of either and (iii) is not connected with the
Depositor, the Master Servicer or any Servicer as an officer, employee,
promoter, underwriter, trustee, partner, director or person performing similar
functions.

            Insurance Policy: Any insurance or performance bond relating to a
Mortgage Loan or the Mortgage Loans, including any hazard insurance, special
hazard insurance, flood insurance, primary mortgage insurance, mortgagor
bankruptcy bond or title insurance.

            Insurance Proceeds: Proceeds paid by any insurer pursuant to any
Insurance Policy covering a Mortgage Loan.

            Insured Expenses: Expenses covered by any Insurance Policy covering
a Mortgage Loan.

            Interest Accrual Amount: As to any Distribution Date and any Class
of Class A Certificates (other than the Class A-PO Certificates), (i) the
product of (a) 1/12th of the Class A Pass-Through Rate for such Class and (b)
the Principal Balance of such Class or, in the case of a Class of Interest Only
Certificates, the related Notional Amount, as of the Determination Date
immediately preceding such Distribution Date minus (ii) the sum of (A) the Class
A Interest Percentage of such Class of the interest portion of any Realized
Losses on the Mortgage Loans on or after the Subordination Depletion Date
pursuant to Section 4.02(c) and (B) the Class A Interest Percentage of such
Class of any Non-Supported Interest Shortfall or Relief Act Shortfall allocated
to the Class A Certificates with respect to such Distribution Date. The Class
A-PO Certificates have no Interest Accrual Amount.

            As to any Distribution Date and any Class of Class B Certificates,
an amount equal to (i) the product of 1/12th of the Class B Pass-Through Rate
and the Principal Balance of such Class as of the Determination Date preceding
such Distribution Date minus (ii) the Class B Interest Percentage of such Class
of the sum of any Non-Supported Interest Shortfall and any Relief Act Shortfall
allocated to the Class B Certificates with respect to such Distribution Date.

            Interest Only Certificates: The Class A-19 Certificates.

            LIBOR: As to any Distribution Date, the arithmetic mean of the
London Interbank offered rate quotations for one month U.S. dollar deposits, as
determined in accordance with the Yield Maintenance Agreement.

            Liquidated Loan: A Mortgage Loan with respect to which the related
Mortgaged Property has been acquired, liquidated or foreclosed and with respect
to which the applicable Servicer determines that all Liquidation Proceeds which
it expects to recover have been recovered.

            Liquidated Loan Loss: With respect to any Distribution Date, the
aggregate of the amount of losses with respect to each Mortgage Loan which
became a Liquidated Loan during the Applicable Unscheduled Principal Receipt
Period with respect to Full Unscheduled Principal Receipts for such Distribution
Date, equal to the excess of (i) the unpaid principal balance of each such
Liquidated Loan, plus accrued interest thereon in accordance with the
amortization schedule at the time applicable thereto at the applicable Net
Mortgage Interest Rate from the Due Date as to which interest was last paid with
respect thereto through the last day of the month preceding the month in which
such Distribution Date occurs, over (ii) Net Liquidation Proceeds with respect
to such Liquidated Loan.

            Liquidation Expenses: Expenses incurred by a Servicer in connection
with the liquidation of any defaulted Mortgage Loan or property acquired in
respect thereof (including, without limitation, legal fees and expenses,
committee or referee fees, and, if applicable, brokerage commissions and
conveyance taxes), any unreimbursed advances (including Periodic Advances)
expended by such Servicer pursuant to its Servicing Agreement or the Master
Servicer or Trustee pursuant hereto respecting the related Mortgage Loan,
including any unreimbursed advances for real property taxes or for property
restoration or preservation of the related Mortgaged Property. Liquidation
Expenses shall not include any previously incurred expenses in respect of an REO
Mortgage Loan which have been netted against related REO Proceeds.

            Liquidation Proceeds: Amounts received by a Servicer (including
Insurance Proceeds) or PMI Advances made by a Servicer in connection with the
liquidation of defaulted Mortgage Loans or property acquired in respect thereof,
whether through foreclosure, sale or otherwise, including payments in connection
with such Mortgage Loans received from the Mortgagor, other than amounts
required to be paid to the Mortgagor pursuant to the terms of the applicable
Mortgage or to be applied otherwise pursuant to law.

            Liquidation Profits: As to any Distribution Date and any Mortgage
Loan that became a Liquidated Loan during the Applicable Unscheduled Principal
Receipt Period with respect to Full Unscheduled Principal Receipts for such
Distribution Date, the excess, if any, of (i) Net Liquidation Proceeds in
respect of such Liquidated Loan over (ii) the unpaid principal balance of such
Liquidated Loan plus accrued interest thereon in accordance with the
amortization schedule at the time applicable thereto at the applicable Net
Mortgage Interest Rate from the Due Date to which interest was last paid with
respect thereto through the last day of the month preceding the month in which
such Distribution Date occurs.

            Loan-to-Value Ratio: The ratio, expressed as a percentage, the
numerator of which is the principal balance of a particular Mortgage Loan at
origination and the denominator of which is the lesser of (x) the appraised
value of the related Mortgaged Property determined in the appraisal used by the
originator at the time of origination of such Mortgage Loan, and (y) if the
Mortgage is originated in connection with a sale of the Mortgaged Property, the
sale price for such Mortgaged Property.

            Lower-Tier Distribution Amount: As defined in Section 4.01(a).

            Lower-Tier REMIC: One of two separate REMICs comprising the Trust
Estate, the assets of which consist of the Mortgage Loans (other than Fixed
Retained Yield), such amounts as shall from time to time be held in the
Certificate Account (other than Fixed Retained Yield), the insurance policies,
if any, relating to a Mortgage Loan and property which secured a Mortgage Loan
and which has been acquired by foreclosure or deed in lieu of foreclosure.

            Master Servicer: Wells Fargo Bank, or its successor in interest.
Initially, the Master Servicer functions shall be performed by the Corporate
Trust Services division of Wells Fargo Bank.

            Master Servicer Errors and Omissions Policy: An insurance policy
covering losses caused by errors or omissions of the Master Servicer and its
personnel.

            Master Servicing Fee: With respect to any Mortgage Loan and any
Distribution Date, the fee payable monthly to the Master Servicer pursuant to
Section 6.05 equal to the Master Servicing Fee Rate of the unpaid principal
balance of such Mortgage Loan.

            Master Servicing Fee Rate: As set forth in Section 11.24.

            Master Servicing Officer: Any officer of the Master Servicer
involved in, or responsible for, the administration and master servicing of the
Mortgage Loans.

            MERS: The Mortgage Electronic Registration Systems, Inc.

            MERS Mortgage Loan: Any MOM Mortgage Loan or any other Mortgage Loan
as to which MERS is (or is intended to be) the mortgagee of record and as to
which a MIN has been assigned.

            Mid-Month Receipt Period: With respect to each Distribution Date,
the one month period beginning on the Determination Date (or, in the case of the
first Distribution Date, from and including the Cut-Off Date) occurring in the
calendar month preceding the month in which such Distribution Date occurs and
ending on the day preceding the Determination Date immediately preceding such
Distribution Date.

            MIN: A MERS Mortgage Identification Number assigned to a Mortgage
Loan registered under MERS.

            MOM: A Mortgage Loan where the related Mortgage names MERS as the
original mortgagee thereof, as to which a MIN has been assigned, and which
Mortgage has not been assigned to any other person.

            Month End Interest: As defined in each Servicing Agreement.

            Monthly Payment: As to any Mortgage Loan (including any REO Mortgage
Loan) and any Due Date, the payment of principal and interest due thereon in
accordance with the amortization schedule at the time applicable thereto (after
adjustment for any Curtailments and Deficient Valuations occurring prior to such
Due Date but before any adjustment to such amortization schedule, other than for
Deficient Valuations, by reason of any bankruptcy or similar proceeding or any
moratorium or similar waiver or grace period).

            Moody's: Moody's Investors Service, Inc. or its successor in
interest.

            Mortgage: The mortgage, deed of trust or other instrument creating a
first lien on Mortgaged Property securing a Mortgage Note together with any
Mortgage Loan Rider, if applicable.

            Mortgage Interest Rate: As to any Mortgage Loan, the per annum rate
at which interest accrues on the unpaid principal balance thereof as set forth
in the related Mortgage Note, which rate is as indicated on the Mortgage Loan
Schedule.

            Mortgage Loan Purchase Agreement: The mortgage loan purchase
agreement dated as of March 28, 2007 between Wells Fargo Bank, as seller, and
the Depositor, as purchaser.

            Mortgage Loan Rider: The standard Fannie Mae/Freddie Mac riders to
the Mortgage Note and/or Mortgage riders required when the Mortgaged Property is
a condominium unit or a unit in a planned unit development.

            Mortgage Loan Schedule: The list delivered by the Depositor to the
Trustee, the Master Servicer and the Custodian of the Mortgage Loans transferred
to the Trustee on the Closing Date as part of the Trust Estate, which list may
be amended following the Closing Date upon conveyance of a Substitute Mortgage
Loan pursuant to Section 2.02 or 2.03 and which list shall set forth at a
minimum the following information as of the close of business on the Cut-Off
Date (or, with respect to Substitute Mortgage Loans, as of the close of business
on the day of substitution) as to each Mortgage Loan:

            (i)   the Mortgage Loan identifying number;

            (ii)  the city, state and zip code of the Mortgaged Property;

            (iii) the type of property;

            (iv)  the Mortgage Interest Rate;

            (v)   the Net Mortgage Interest Rate;

            (vi)  the Monthly Payment;

            (vii) the original number of months to maturity;

            (viii) the scheduled maturity date;

            (ix)  the Cut-Off Date Principal Balance;

            (x)   the Loan-to-Value Ratio at origination;

            (xi)  whether such Mortgage Loan is a Subsidy Loan;

            (xii) whether such Mortgage Loan is covered by primary mortgage
                  insurance;

            (xiii) the applicable Servicing Fee Rate;

            (xiv) the Master Servicing Fee Rate;

            (xv)  the Fixed Retained Yield Rate, if applicable;

            (xvi) in the case of any Mortgage Loan initially serviced by Wells
                  Fargo Bank, whether such Mortgage Loan is a Type 1 Mortgage
                  Loan or a Type 2 Mortgage Loan; and

            (xvii) the name of the Servicer.

            Such schedule may consist of multiple reports that collectively set
forth all of the information required.

            Mortgage Loans: Each of the mortgage loans transferred and assigned
to the Trustee on the Closing Date pursuant to Section 2.01(a) and any mortgage
loans substituted therefor pursuant to Section 2.02 or 2.03, in each case as
from time to time are included in the Trust Estate as identified in the Mortgage
Loan Schedule.

            Mortgage Note: The note or other evidence of indebtedness evidencing
the indebtedness of a Mortgagor under a Mortgage Loan together with any related
Mortgage Loan Riders, if applicable.

            Mortgaged Property: The property subject to a Mortgage, which may
include Co-op Shares or residential long-term leases.

            Mortgagor: The obligor on a Mortgage Note.

            Net Liquidation Proceeds: As to any defaulted Mortgage Loan,
Liquidation Proceeds net of Liquidation Expenses.

            Net Mortgage Interest Rate: With respect to each Mortgage Loan, a
rate equal to (i) the Mortgage Interest Rate on such Mortgage Loan minus (ii)
the sum of (a) the applicable Servicing Fee Rate, as set forth in Section 11.23
with respect to such Mortgage Loan, (b) the Master Servicing Fee Rate, as set
forth in Section 11.24 with respect to such Mortgage Loan and (c) the Fixed
Retained Yield Rate, if any, with respect to such Mortgage Loan. Any regular
monthly computation of interest at such rate shall be based upon annual interest
at such rate on the applicable amount divided by twelve.

            Net REO Proceeds: As to any REO Mortgage Loan, REO Proceeds net of
any related expenses of the applicable Servicer.

            NMWHFIT: A "Non-Mortgage Widely Held Fixed Investment Trust" as that
term is defined in Treasury Regulations section 1.671-5(b)(12) or successor
provisions.

            Non-permitted Foreign Holder: As defined in Section 5.02(d).

            Non-PO Fraction: With respect to any Mortgage Loan, the lesser of
(i) 1.00 and (ii) the quotient obtained by dividing the Net Mortgage Interest
Rate for such Mortgage Loan by 6.000%.

            Non-PO Recovery: As to any Distribution Date, the amount of all
Recoveries received during the Applicable Unscheduled Principal Receipt Periods
for such Distribution Date less the Class A-PO Recovery for such Distribution
Date.

            Nonrecoverable Advance: Any portion of a Periodic Advance previously
made or proposed to be made in respect of a Mortgage Loan which has not been
previously reimbursed to the applicable Servicer, the Master Servicer or the
Trustee, as the case may be, and which the applicable Servicer, the Master
Servicer or the Trustee determines will not, or in the case of a proposed
Periodic Advance would not, be ultimately recoverable from Liquidation Proceeds
or other recoveries in respect of the related Mortgage Loan. The determination
by the applicable Servicer, the Master Servicer or the Trustee (i) that it has
made a Nonrecoverable Advance or (ii) that any proposed Periodic Advance, if
made, would constitute a Nonrecoverable Advance, shall be evidenced by an
Officer's Certificate of such Servicer delivered to the Master Servicer for
redelivery to the Trustee or, in the case of a Master Servicer determination, an
Officer's Certificate of the Master Servicer delivered to the Trustee, in each
case detailing the reasons for such determination.

            Non-Supported Interest Shortfall: With respect to any Distribution
Date, the sum of (i) the excess, if any, of the aggregate Prepayment Interest
Shortfall on the Mortgage Loans over the aggregate Compensating Interest with
respect to such Distribution Date and (ii) Curtailment Interest Shortfalls with
respect to such Distribution Date. With respect to each Distribution Date
occurring on or after the Subordination Depletion Date, the Non-Supported
Interest Shortfall determined pursuant to the preceding sentence will be
increased by the amount of any Subordination Depletion Date Interest Shortfall
for such Distribution Date. Any Non-Supported Interest Shortfall will be
allocated to (a) the Class A Certificates (other than the Class A-PO
Certificates) according to the percentage obtained by dividing the Class A
Non-PO Principal Balance by the Aggregate Non-PO Principal Balance and (b) the
Class B Certificates according to the percentage obtained by dividing the Class
B Principal Balance by the Aggregate Non-PO Principal Balance.

            Non-U.S. Person: As defined in Section 4.01(g).

            Notional Amount: The Class A-19 Notional Amount.

            NYCEMA: A New York Consolidation, Extension and Modification
Agreement.

            Officer's Certificate: With respect to any Person, a certificate
signed by the Chairman of the Board, the President or a Vice President, and by
the Treasurer, the Secretary or one of the Assistant Treasurers, Assistant
Secretaries or any other duly authorized officer of such Person (or, in the case
of a Person which is not a corporation, signed by the person or persons having
like responsibilities).

            Opinion of Counsel: A written opinion of counsel, who may be outside
or salaried counsel for the Depositor, a Servicer or the Master Servicer, or any
affiliate of the Depositor, a Servicer or the Master Servicer, acceptable to the
Trustee if such opinion is to be delivered to the Trustee; provided, however,
that with respect to REMIC matters, matters relating to the determination of
Eligible Accounts or matters relating to transfers of Certificates, such counsel
shall be Independent.

            Optimal Adjustment Event: With respect to any Class of Class B
Certificates and any Distribution Date, an Optimal Adjustment Event will occur
with respect to such Class if: (i) the Principal Balance of such Class on the
Determination Date succeeding such Distribution Date would have been reduced to
zero (regardless of whether such Principal Balance was reduced to zero as a
result of principal distribution or the allocation of Realized Losses) and (ii)
(a) the Principal Balance of any Class of Class A Non-PO Certificates would be
subject to further reduction as a result of the third sentence of the definition
of Principal Balance or (b) the Principal Balance of a Class of Class B
Certificates with a lower numerical designation would be reduced with respect to
such Distribution Date as a result of the application of the proviso in the
definition of Class B-1 Principal Balance, Class B-2 Principal Balance, Class
B-3 Principal Balance, Class B-4 Principal Balance, Class B-5 Principal Balance
or Class B-6 Principal Balance.

            Original Aggregate Non-PO Principal Balance: The Aggregate Non-PO
Principal Balance as of the Cut-Off Date, as set forth in Section 11.06.

            Original Class A Percentage: The Class A Percentage as of the
Cut-Off Date as set forth in Section 11.03.

            Original Class A-19 Notional Amount: The Original Class A-19
Notional Amount as set forth in Section 11.05.

            Original Class B Principal Balance: The sum of the Original Class
B-1 Principal Balance, the Original Class B-2 Principal Balance, the Original
Class B-3 Principal Balance, the Original Class B-4 Principal Balance, the
Original Class B-5 Principal Balance and the Original Class B-6 Principal
Balance, as set forth in Section 11.07.

            Original Class B-1 Fractional Interest: As to the first Distribution
Date, the percentage obtained by dividing the sum of the Original Class B-2
Principal Balance, the Original Class B-3 Principal Balance, the Original Class
B-4 Principal Balance, the Original Class B-5 Principal Balance and the Original
Class B-6 Principal Balance by the Original Aggregate Non-PO Principal Balance.
The Original Class B-1 Fractional Interest is specified in Section 11.09.

            Original Class B-2 Fractional Interest: As to the first Distribution
Date, the percentage obtained by dividing the sum of the Original Class B-3
Principal Balance, the Original Class B-4 Principal Balance, the Original Class
B-5 Principal Balance and the Original Class B-6 Principal Balance by the
Original Aggregate Non-PO Principal Balance. The Original Class B-2 Fractional
Interest is specified in Section 11.10.

            Original Class B-3 Fractional Interest: As to the first Distribution
Date, the percentage obtained by dividing the sum of the Original Class B-4
Principal Balance, the Original Class B-5 Principal Balance and the Original
Class B-6 Principal Balance by the Original Aggregate Non-PO Principal Balance.
The Original Class B-3 Fractional Interest is specified in Section 11.11.

            Original Class B-4 Fractional Interest: As to the first Distribution
Date, the percentage obtained by dividing the sum of the Original Class B-5
Principal Balance and the Original Class B-6 Principal Balance by the Original
Aggregate Non-PO Principal Balance. The Original Class B-4 Fractional Interest
is specified in Section 11.12.

            Original Class B-5 Fractional Interest: As to the first Distribution
Date, the percentage obtained by dividing the Original Class B-6 Principal
Balance by the Original Aggregate Non-PO Principal Balance. The Original Class
B-5 Fractional Interest is specified in Section 11.13.

            Original Class B-1 Percentage: The Class B-1 Percentage as of the
Cut-Off Date, as set forth in Section 11.14.

            Original Class B-2 Percentage: The Class B-2 Percentage as of the
Cut-Off Date, as set forth in Section 11.15.

            Original Class B-3 Percentage: The Class B-3 Percentage as of the
Cut-Off Date, as set forth in Section 11.16.

            Original Class B-4 Percentage: The Class B-4 Percentage as of the
Cut-Off Date, as set forth in Section 11.17.

            Original Class B-5 Percentage: The Class B-5 Percentage as of the
Cut-Off Date, as set forth in Section 11.18.

            Original Class B-6 Percentage: The Class B-6 Percentage as of the
Cut-Off Date, as set forth in Section 11.19.

            Original Class B-1 Principal Balance: The Class B-1 Principal
Balance as of the Cut-Off Date, as set forth in Section 11.08.

            Original Class B-2 Principal Balance: The Class B-2 Principal
Balance as of the Cut-Off Date, as set forth in Section 11.08.

            Original Class B-3 Principal Balance: The Class B-3 Principal
Balance as of the Cut-Off Date, as set forth in Section 11.08.

            Original Class B-4 Principal Balance: The Class B-4 Principal
Balance as of the Cut-Off Date, as set forth in Section 11.08.

            Original Class B-5 Principal Balance: The Class B-5 Principal
Balance as of the Cut-Off Date, as set forth in Section 11.08.

            Original Class B-6 Principal Balance: The Class B-6 Principal
Balance as of the Cut-Off Date, as set forth in Section 11.08.

            Original Notional Amount: The Original Class A-19 Notional Amount as
set forth in Section 11.05.

            Original Principal Balance: Any of the Original Principal Balances
of the Classes of Class A Certificates as set forth in Section 11.04; the
Original Class B-1 Principal Balance, Original Class B-2 Principal Balance,
Original Class B-3 Principal Balance, Original Class B-4 Principal Balance,
Original Class B-5 Principal Balance or Original Class B-6 Principal Balance, as
set forth in Section 11.08.

            Other Servicer: Any of the Servicers other than Wells Fargo Bank.

            Other Servicer Mortgage Loan: Any of the Mortgage Loans, if any,
identified on the Mortgage Loan Schedule as serviced by an Other Servicer, as
such Mortgage Loan Schedule may be amended from time to time in connection with
a substitution pursuant to Section 2.02 or 2.03, which Mortgage Loan is serviced
under an Other Servicing Agreement.

            Other Servicing Agreements: The Servicing Agreements other than the
Wells Fargo Bank Servicing Agreement.

            Outstanding Mortgage Loan: As to any Due Date, a Mortgage Loan
(including an REO Mortgage Loan) which was not the subject of a Full Unscheduled
Principal Receipt prior to such Due Date and which was not repurchased by the
Depositor prior to such Due Date pursuant to Section 2.02, 2.03 or 3.08.

            Owner Mortgage Loan File: A file maintained by the Custodian for
each Mortgage Loan that contains the documents specified in Section 2.01(a) and
any additional documents required to be added to the Owner Mortgage Loan File
pursuant to this Agreement.

            PAC I Certificates: The Class A-16, Class A-17, Class A-18, Class
A-20 and Class A-21 Certificates.

            PAC I Group: The Class A-16, Class A-17, Class A-18, Class A-20 and
Class A-21 Certificates.

            PAC I Principal Amount: As defined in Section 4.01(c).

            PAC II Certificates: The Class A-9 Certificates.

            PAC II Principal Amount: As defined in Section 4.01(c).

            Partial Liquidation Proceeds: Liquidation Proceeds received by a
Servicer prior to the Unscheduled Principal Receipt Period in which the related
Mortgage Loan became a Liquidated Loan.

            Partial Unscheduled Principal Receipt: An Unscheduled Principal
Receipt which is not a Full Unscheduled Principal Receipt.

            Paying Agent: The Person authorized to make distributions to
Certificateholders with respect to the Certificates and to forward to
Certificateholders the periodic and annual statements required by Section 4.04.
The Paying Agent may be the Trustee. The initial Paying Agent is appointed in
Section 4.03(b).

            Paying Agent Agreement: As defined in Section 4.03(b).

            Payment Account: The account maintained pursuant to Section 4.03(a).

            Percentage Interest: With respect to a Class A Certificate of a
Class (other than an Interest Only Certificate), the undivided percentage
interest obtained by dividing the original principal balance of such Certificate
by the Original Principal Balance of such Class of Class A Certificates. With
respect to an Interest Only Certificate, the undivided percentage interest
obtained by dividing the original notional amount evidenced by such Interest
Only Certificate by the Original Notional Amount of such Class of Interest Only
Certificates. With respect to a Class B Certificate of a Class, the undivided
percentage interest obtained by dividing the original principal balance of such
Certificate by the Original Principal Balance of such Class of Class B
Certificates.

            Periodic Advance: The aggregate of the advances required to be made
by a Servicer on any Remittance Date pursuant to its Servicing Agreement or by
the Master Servicer or the Trustee hereunder on any Distribution Date, the
amount of any such advances being equal to the total of all Monthly Payments
(adjusted, in each case (i) in respect of interest, to the applicable Mortgage
Interest Rate less the applicable Servicing Fee in the case of Periodic Advances
made by a Servicer and to the applicable Net Mortgage Interest Rate in the case
of Periodic Advances made by the Master Servicer or Trustee and (ii) by the
amount of any related Debt Service Reductions or reductions in the amount of
interest collectable from the Mortgagor pursuant to the Servicemembers Civil
Relief Act, as it may be amended from time to time, or similar legislation or
regulations then in effect) on the Mortgage Loans, that (x) were delinquent as
of the close of business on the related Determination Date, (y) were not the
subject of a previous Periodic Advance by such Servicer or of a Periodic Advance
by the Master Servicer or the Trustee, as the case may be and (z) have not been
determined by the Master Servicer, such Servicer or Trustee to be Nonrecoverable
Advances. For purposes of the preceding sentence, the Monthly Payment on each
Balloon Loan with a delinquent Balloon Payment is equal to the assumed monthly
payment that would have been due on the related Due Date based on the original
principal amortization schedule for such Balloon Loan.

            Person: Any individual, corporation, partnership, joint venture,
association, joint-stock company, trust, unincorporated organization or
government or any agency or political subdivision thereof.

            Plan: As defined in Section 5.02(c).

            PMI Advance: As defined in the related Servicing Agreement, if
applicable.

            PO Fraction: With respect to any Discount Mortgage Loan, the
difference between 1.0 and the Non-PO Fraction for such Mortgage Loan; with
respect to any other Mortgage Loan, zero.

            Pool Balance (Non-PO Portion): As of any Distribution Date, the sum
of the amounts for each Mortgage Loan that is an Outstanding Mortgage Loan of
the product of (i) the Non-PO Fraction for such Mortgage Loan and (ii) the
Scheduled Principal Balance of such Mortgage Loan.

            Pool Balance (PO Portion): As of any Distribution Date, the sum of
the amounts for each Mortgage Loan that is an Outstanding Mortgage Loan of the
product of (i) the PO Fraction for such Mortgage Loan and (ii) the Scheduled
Principal Balance of such Mortgage Loan.

            Pool Distribution Amount: As of any Distribution Date, the funds
eligible for distribution to the Class A Certificates and Class B Certificates
on such Distribution Date, which shall be the sum of (i) all previously
undistributed payments or other receipts on account of principal and interest on
or in respect of the Mortgage Loans (including, without limitation, the proceeds
of any repurchase of a Mortgage Loan by the Depositor and any Substitution
Principal Amount) received by the Master Servicer with respect to the applicable
Remittance Date in the month of such Distribution Date and any Unscheduled
Principal Receipts received by the Master Servicer on or prior to the Business
Day preceding such Distribution Date, (ii) all Periodic Advances made by a
Servicer pursuant to the related Servicing Agreement or Periodic Advances made
by the Master Servicer or the Trustee pursuant to Section 3.03, (iii) any
remaining Reimbursement Amount as provided in Section 4.01(a) and (iv) all other
amounts (including any Insurance Proceeds and Compensating Interest) required to
be placed in the Certificate Account by the Servicers on or before the
applicable Remittance Date or by the Master Servicer or the Trustee on or prior
to the Distribution Date, but excluding the following:

            (a) amounts received as late payments of principal or interest and
      respecting which the Master Servicer or the Trustee has made one or more
      unreimbursed Periodic Advances;

            (b) the portion of Liquidation Proceeds used to reimburse any
      unreimbursed Periodic Advances by the Master Servicer or the Trustee;

            (c) that portion of each payment of interest on a particular
      Mortgage Loan which represents (i) the Fixed Retained Yield, if any, (ii)
      the applicable Servicing Fee and (iii) the Master Servicing Fee;

            (d) all amounts representing scheduled payments of principal and
      interest due after the Due Date occurring in the month in which such
      Distribution Date occurs;

            (e) all Unscheduled Principal Receipts received by the Servicers
      after the Applicable Unscheduled Principal Receipt Period relating to the
      Distribution Date for the applicable type of Unscheduled Principal
      Receipt, and all related payments of interest on such amounts;

            (f) all repurchase proceeds with respect to Mortgage Loans
      repurchased by the Depositor pursuant to Section 2.02, 2.03 or 3.08 on or
      following the Determination Date in the month in which such Distribution
      Date occurs and the Substitution Principal Amounts with respect to any
      Mortgage Loans for which Mortgage Loans were substituted on or following
      the Determination Date in the month in which such Distribution Date
      occurs;

            (g) that portion of Liquidation Proceeds and REO Proceeds which
      represents any unpaid Servicing Fee or Master Servicing Fee;

            (h) all income from Eligible Investments that is held in the
      Certificate Account for the account of the Master Servicer;

            (i) Liquidation Profits;

            (j) Month End Interest;

            (k) all amounts reimbursable to a Servicer for PMI Advances; and

            (l) all other amounts permitted to be withdrawn from the Certificate
      Account, to the extent not covered by clauses (a) through (k) above, or
      not required to be deposited in the Certificate Account under this
      Agreement.

            Pool Scheduled Principal Balance: As to any Distribution Date, the
aggregate Scheduled Principal Balance of all Mortgage Loans that were
Outstanding Mortgage Loans on the Due Date in the month preceding the month of
such Distribution Date.

            Premium Mortgage Loan: A Mortgage Loan with a Net Mortgage Interest
Rate equal to or greater than 6.000%.

            Prepayment In Full: With respect to any Mortgage Loan, a Mortgagor
payment consisting of a Principal Prepayment in the amount of the outstanding
principal balance of such loan and resulting in the full satisfaction of such
obligation.

            Prepayment Interest Shortfall: On any Distribution Date, the amount
of interest, if any, that would have accrued on any Mortgage Loan which was the
subject of a Prepayment in Full at the Net Mortgage Interest Rate for such
Mortgage Loan from the date of its Prepayment in Full (but in the case of a
Prepayment in Full where the Applicable Unscheduled Principal Receipt Period is
the Mid-Month Receipt Period, only if the date of the Prepayment in Full is on
or after the Determination Date in the month prior to the month of such
Distribution Date and prior to the first day of the month of such Distribution
Date) through the last day of the month prior to the month of such Distribution
Date.

            Prepayment Shift Percentage: As to any Distribution Date, the
percentage indicated below:

                                                                      Prepayment
  Distribution Date Occurring In                                      Shift
                                                                      Percentage
  April 2007 through March 2012.................................         0%
  April 2012 through March 2013..................................       30%
  April 2013 through March 2014..................................       40%
  April 2014 through March 2015..................................       60%
  April 2015 through March 2016..................................       80%
  April 2016 and thereafter......................................      100%

            Principal Adjustment: In the event that the Class B-1 Optimal
Principal Amount, Class B-2 Optimal Principal Amount, Class B-3 Optimal
Principal Amount, Class B-4 Optimal Principal Amount, Class B-5 Optimal
Principal Amount or Class B-6 Optimal Principal Amount is calculated in
accordance with the proviso in such definition with respect to any Distribution
Date, the Principal Adjustment for such Class of Class B Certificates shall
equal the difference between (i) the amount that would have been distributed to
such Class as principal in accordance with Section 4.01(a) for such Distribution
Date, calculated without regard to such proviso and assuming there are no
Principal Adjustments for such Distribution Date and (ii) the Adjusted Principal
Balance for such Class.

            Principal Balance: As of the first Determination Date and as to any
Class of Class A Certificates (other than the Interest Only Certificates), the
Original Principal Balance of such Class. As of any subsequent Determination
Date prior to the Subordination Depletion Date and as to any Class of Class A
Certificates (other than the Interest Only Certificates and the Class A-PO
Certificates), the Original Principal Balance of such Class less the sum of all
amounts previously distributed in respect of such Class (increased in the case
of a Class of Accrual Certificates by the Accrual Distribution Amounts for such
Class with respect to prior Distribution Dates) on prior Distribution Dates (i)
pursuant to Paragraph third clause (1) of Section 4.01(a), (ii) as a result of a
Principal Adjustment and (iii), if applicable, from the Accrual Distribution
Amounts for such prior Distribution Dates. After the Subordination Depletion
Date, each such Principal Balance of a Class of Class A Certificates (other than
the Class A-PO Certificates) will also be reduced (if clause (a) is greater than
clause (b)) or increased (if clause (a) is less than clause (b)) on each
Determination Date by an amount equal to the product of the Class A Loss
Percentage of such Class and the difference, if any, between (a) the Class A
Non-PO Principal Balance as of such Determination Date without regard to this
sentence and (b) the Adjusted Pool Amount (Non-PO Portion) for the preceding
Distribution Date; provided, however, that the amount of any such reduction for
the Class A-5, Class A-8, Class A-14 and Class A-15 Certificates will be
decreased by the Class A-2 Loss Allocation Amount and the amount of any such
reduction for the Class A-7 Certificates will be decreased by the Class A-12
Loss Allocation Amount. After the Subordination Depletion Date, the Principal
Balance for the Class A-2 Certificates will additionally be reduced by the Class
A-2 Loss Allocation Amount and the Principal Balance for the Class A-12
Certificates will additionally be reduced by the Class A-12 Loss Allocation
Amount. In addition, any increase allocated to the Class A-5, Class A-8, Class
A-14 and Class A-15 Certificates pursuant to the third sentence above will
instead increase the Principal Balance of the Class A-2 Certificates and any
increase allocated to the Class A-7 Certificates pursuant to the third sentence
above will instead increase the Principal Balance of the Class A-12
Certificates. Notwithstanding the foregoing, on any Distribution Date in which
the sum of the Class A-5 Loss Amount, Class A-8 Loss Amount, Class A-14 Loss
Amount and Class A-15 Loss Amount exceeds the Principal Balance of the Class A-2
Certificates prior to any reduction for the Class A-2 Loss Allocation Amount,
such excess will be allocated, pro rata, based on the Class A-5 Loss Amount,
Class A-8 Loss Amount, Class A-14 Loss Amount and Class A-15 Loss Amount, in
reduction of the Principal Balances of the Class A-5, Class A-8, Class A-14 and
Class A-15 Certificates.

            On any Distribution Date, the reduction to the Principal Balances
which would otherwise be allocated to the Class A-5, Class A-8, Class A-14 and
Class A-15 Certificates pursuant to the third sentence of the preceding
paragraph, will be allocated to the Class A-2 Certificates proportionately up to
an amount equal to $1,925,000, $566,000, $640,000 and $10,449,000, respectively,
until the Principal Balance of the Class A-2 Certificates is reduced to zero.

            As of any subsequent Determination Date and as to the Class A-PO
Certificates, the Original Principal Balance of such Class less the sum of all
amounts previously distributed in respect of the Class A-PO Certificates on
prior Distribution Dates pursuant to Paragraph third clause (2) of Section
4.01(a). The Principal Balance of the Class A-PO Certificates will also be
reduced (if clause (x) is greater than clause (y)) or increased (if clause (x)
is less than clause (y)) on each Determination Date by the difference, if any,
between (x) the Principal Balance of the Class A-PO Certificates as of such
Determination Date without regard to this sentence and (y) the Adjusted Pool
Amount (PO Portion) for the preceding Distribution Date.

            As to the Class B Certificates, the Class B-1 Principal Balance,
Class B-2 Principal Balance, Class B-3 Principal Balance, Class B-4 Principal
Balance, Class B-5 Principal Balance and Class B-6 Principal Balance,
respectively.

            Notwithstanding the foregoing, no Principal Balance of a Class will
be increased on any Determination Date such that the Principal Balance of such
Class exceeds its Original Principal Balance (plus any Accrual Distribution
Amounts previously added to the Principal Balance of a Class of Accrual
Certificates) less all amounts previously distributed in respect of such Class
on prior Distribution Dates pursuant to Paragraph third clause (1) of Section
4.01(a), Paragraph third clause (2) of Section 4.01(a), or Paragraphs seventh,
tenth, thirteenth, sixteenth, nineteenth or twenty-second of Section 4.01(a).

            Principal Prepayment: Any Mortgagor payment on a Mortgage Loan which
is received in advance of its Due Date and is not accompanied by an amount
representing scheduled interest for any period subsequent to the date of
prepayment.

            Prior Month Receipt Period: With respect to each Distribution Date,
the calendar month preceding the month in which such Distribution Date occurs.

            Priority Amount: For any Distribution Date means the sum of (a) the
product of (i) the Priority Percentage, (ii) the Shift Percentage and (iii) the
Scheduled Principal Amount and (b) the product of (i) the Priority Percentage,
(ii) the Prepayment Shift Percentage and (iii) the Unscheduled Principal Amount.

            Priority Percentage: The sum of the Principal Balances of the Class
A-2, Class A-3 and Class A-15 Certificates divided by the Aggregate Non-PO
Principal Balance.

            Prohibited Transaction Tax: Any tax imposed under Section 860F of
the Code.

            Prospectus: The prospectus dated February 26, 2007 as supplemented
by the prospectus supplement dated March 26, 2007, relating to the Class A,
Class B-1, Class B-2 and Class B-3 Certificates.

            Prudent Servicing Practices: The standard of care set forth in each
Servicing Agreement.

            Rating Agency: Any nationally recognized statistical credit rating
agency, or its successor, that rated one or more Classes of the Certificates at
the request of the Depositor at the time of the initial issuance of the
Certificates. The Rating Agencies for the Class A Certificates (other than the
Class A-2, Class A-5, Class A-8, Class A-14, Class A-15 and Class A-R
Certificates) are Fitch and Moody's. The Rating Agencies for the Class A-2,
Class A-5, Class A-8, Class A-14 and Class A-15 Certificates are Fitch, Moody's
and S&P. The Rating Agency for the Class A-R, Class B-1, Class B-2, Class B-3,
Class B-4 and Class B-5 Certificates is Fitch. If any such agency or a successor
is no longer in existence, "Rating Agency" shall be such statistical credit
rating agency, or other comparable Person, designated by the Depositor, notice
of which designation shall be given to the Trustee and the Master Servicer.
References herein to the highest short-term rating category of a Rating Agency
shall mean F-1+ in the case of Fitch, P-1 in the case of Moody's, A-1 in the
case of S&P, and in the case of any other Rating Agency shall mean its
equivalent of such ratings. References herein to the highest long-term rating
categories of a Rating Agency shall mean AAA in the case of Fitch and S&P and
Aaa in the case of Moody's, and in the case of any other Rating Agency shall
mean its equivalent of such ratings without any plus or minus.

            Realized Losses: With respect to any Distribution Date, (i)
Liquidated Loan Losses incurred on Liquidated Loans for which the Liquidation
Proceeds were received during the Applicable Unscheduled Principal Receipt
Period with respect to Full Unscheduled Principal Receipts with respect to such
Distribution Date and (ii) Bankruptcy Losses incurred during the period
corresponding to the Applicable Unscheduled Principal Receipt Period with
respect to Full Unscheduled Principal Receipts for such Distribution Date.

            Record Date: For (i) the Class A-5 Certificates, the Business Day
preceding the related Distribution Date and (ii) all other Certificates, the
last Business Day of the month preceding the month of the related Distribution
Date.

            Recovery: Any amount received (net of any reimbursable expenses) on
a Mortgage Loan subsequent to such Mortgage Loan being determined to be a
Liquidated Loan.

            Reduction Amount: As defined in Section 4.01(c).

            Regulation AB: Subpart 229.1100 - Asset Backed Securities
(Regulation AB), 17 C.F.R. ss.ss.229.1100-229.1123, as such may be amended from
time to time, and subject to such clarification and interpretation as have been
publicly provided by the Commission in the adopting release (Asset-Backed
Securities, Securities Act Release No. 33-8518, 70 Fed. Reg. 1,506 (Jan. 7,
2005)) or by the staff of the Commission, or as may be provided by the
Commission or its staff from time to time.

            Reimbursement Amount: As defined in Section 2.03(c).

            Relevant Servicing Criteria: The Servicing Criteria applicable to
the Master Servicer, the Trustee, the Custodian or the Servicers, as set forth
on Exhibit R attached hereto and the Servicing Criteria applicable to any
Special Servicer as set forth in the applicable Special Servicing Agreement. For
clarification purposes, multiple parties can have responsibility for the same
Relevant Servicing Criteria. With respect to a Servicing Function Participant
engaged by the Master Servicer, the Trustee, the Custodian, the Special Servicer
(if applicable) or a Servicer, the term "Relevant Servicing Criteria" refers to
the portion of the Relevant Servicing Criteria applicable to the party engaging
such Servicing Function Participant insofar as the functions required to be
performed by such party are to be performed by the Servicing Function
Participant.

            Relief Act Shortfall: Any interest shortfalls arising as a result of
the reduction in the amount of monthly interest payments on any Mortgage Loans
as a result of the application of the Servicemembers Civil Relief Act, as it may
be amended from time to time, or comparable state legislation. Any Relief Act
Shortfall will be allocated to (a) the Class A Certificates (other than the
Class A-PO Certificates) according to the percentage obtained by dividing the
Class A Non-PO Principal Balance by the Aggregate Non-PO Principal Balance and
(b) the Class B Certificates according to the percentage obtained by dividing
the Class B Principal Balance by the Aggregate Non-PO Principal Balance.

            REMIC: A "real estate mortgage investment conduit" as defined in
Code Section 860D. The Reserve Fund and the Yield Maintenance Agreement are not
assets of either REMIC.

            REMIC Provisions: Provisions of the federal income tax law relating
to REMICs, which appear at Sections 860A through 860G of Part IV of Subchapter M
of Chapter 1 of Subtitle A of the Code, and related provisions, and U.S.
Department of the Treasury temporary, proposed or final regulations promulgated
thereunder, as the foregoing are in effect (or with respect to proposed
regulations, are proposed to be in effect) from time to time.

            Remittance Date: As defined in each of the Servicing Agreements.

            REO Mortgage Loan: Any Mortgage Loan which is not a Liquidated Loan
and as to which the indebtedness evidenced by the related Mortgage Note is
discharged and the related Mortgaged Property is held as part of the Trust
Estate.

            REO Proceeds: Proceeds received in respect of any REO Mortgage Loan
(including, without limitation, proceeds from the rental of the related
Mortgaged Property).

            Reportable Event: As defined in Section 3.12(c).

            Repurchase Price: With respect to any Mortgage Loan repurchased
pursuant to Section 2.02, 2.03 or 3.08 hereof, the sum of (a) 100% of the unpaid
principal balance of such Mortgage Loan plus (b) accrued interest at the
Mortgage Interest Rate less any Fixed Retained Yield, through the last day of
the month in which such repurchase takes place.

            Request for Release: A request for release (which may be in
electronic form) in substantially the form attached as Exhibit G hereto.

            Reserve Fund: The trust account created and maintained by the Master
Servicer pursuant to Section 4.07 which shall be entitled the "Reserve Fund,
Wells Fargo Bank, N.A., as Master Servicer, in trust for registered Holders of
the Class A-5 Certificates of the Wells Fargo Mortgage Backed Securities 2007-4
Trust" and which must be an Eligible Account. Amounts on deposit in the Reserve
Fund shall not be invested. The Reserve Fund shall not be an asset of either
REMIC formed under this Agreement.

            Residual Certificate: The Class A-R Certificate.

            Responsible Officer: When used with respect to the Trustee, the
Master Servicer, the Custodian, the Paying Agent or the Authenticating Agent,
any officer of the Corporate Trust Department of the Trustee, the Master
Servicer, the Custodian, the Paying Agent or the Authenticating Agent having
direct responsibility for the administration of this Agreement, including any
Senior Vice President, any Vice President, any Assistant Vice President, any
Assistant Secretary, any Trust Officer or Assistant Trust Officer, or any other
employee of the Trustee, the Master Servicer, the Custodian, the Paying Agent or
the Authenticating Agent customarily performing functions similar to those
performed by any of the above-designated officers. When used with respect to a
Servicer, a Servicing Officer.

            Retained Mortgage Loan File: A file maintained by Wells Fargo Bank
prior to any Document Transfer Date for each Mortgage Loan that contains the
documents specified in Section 2.01(b) and any additional documents required to
be added to the Retained Mortgage Loan File pursuant to this Agreement.

            Rule 144A: Rule 144A promulgated under the 1933 Act.

            S&P: Standard & Poor's, a division of The McGraw-Hill Companies,
Inc., or its successor in interest.

            Sarbanes-Oxley Certification: As defined in Section 3.12(b).

            Scheduled Certificates: The Class A-5 Certificates.

            Scheduled Principal Amount: The sum for each outstanding Mortgage
Loan (including each defaulted Mortgage Loan with respect to which the related
Mortgaged Property has been acquired by the Trust Estate) of the product of (A)
the Non-PO Fraction for such Mortgage Loan and (B) the sum of the amounts
described in clauses Iy(i) and Iy(iv) of the definition of Class A Non-PO
Optimal Principal Amount but without such amounts being multiplied by the Class
A Percentage.

            Scheduled Principal Balance: As to any Mortgage Loan and
Distribution Date, the principal balance of such Mortgage Loan as of the Due
Date in the month preceding the month of such Distribution Date as specified in
the amortization schedule at the time relating thereto (before any adjustment to
such amortization schedule by reason of any bankruptcy (other than Deficient
Valuations) or similar proceeding or any moratorium or similar waiver or grace
period) after giving effect to (A) Unscheduled Principal Receipts received or
applied by the applicable Servicer during the related Unscheduled Principal
Receipt Period for each applicable type of Unscheduled Principal Receipt related
to the Distribution Date occurring in the month preceding such Distribution
Date, (B) Deficient Valuations incurred prior to such Due Date and (C) the
payment of principal due on such Due Date and irrespective of any delinquency in
payment by the related Mortgagor. Accordingly, the Scheduled Principal Balance
of a Mortgage Loan which becomes a Liquidated Loan at any time through the last
day of such related Unscheduled Principal Receipt Period shall be zero.

            Servicer Mortgage Loan File: As defined in each of the Servicing
Agreements.

            Servicers: Wells Fargo Bank, as a Servicer under the related
Servicing Agreement. Initially the servicing functions performed by Wells Fargo
Bank shall be performed by the Wells Fargo Home Mortgage division of Wells Fargo
Bank.

            Servicing Agreements: Each of the Servicing Agreements executed with
respect to a portion of the Mortgage Loans by one of the Servicers, which
agreements are attached hereto, collectively, as Exhibit L.

            Servicing Criteria: The "servicing criteria" set forth in Item
1122(d) of Regulation AB, as such may be amended from time to time.

            Servicing Fee: With respect to any Servicer, as defined in its
Servicing Agreement.

            Servicing Fee Rate: With respect to a Mortgage Loan, as set forth in
Section 11.23.

            Servicing Function Participant: Any Subservicer, Subcontractor or
any other Person, other than the Master Servicer, the Trustee, the Custodian,
the Special Servicer (if applicable) and the Servicers, that is performing
activities addressed by the Servicing Criteria.

            Servicing Officer: Any officer of a Servicer involved in, or
responsible for, the administration and servicing of the Mortgage Loans.

            Shift Percentage: As to any Distribution Date, the percentage
indicated below:

Distribution Date Occurring In                                        Shift
                                                                      Percentage
April 2007 through March 2012                                            0%
April 2012 and thereafter                                              100%

            Similar Law: As defined in Section 5.02(c).

            Special Servicer: As defined in Section 3.08.

            Special Servicing Agreement: As defined in Section 3.08.

            Single Certificate: A Certificate of any Class that evidences the
smallest permissible Denomination for such Class, as set forth in Section 11.22.

            Startup Day: As defined in Section 2.05.

            Subcontractor: Any vendor, subcontractor or other Person that is not
responsible for the overall servicing of Mortgage Loans but performs one or more
discrete functions identified in Item 1122(d) of Regulation AB with respect to
Mortgage Loans under the direction or authority of any Servicer (or a
Subservicer of any Servicer), the Master Servicer, the Trustee or the Custodian.

            Subordinated Percentage: As to any Distribution Date, the percentage
which is the difference between 100% and the Class A Percentage for such date.

            Subordinated Prepayment Percentage: As to any Distribution Date, the
percentage which is the difference between 100% and the Class A Prepayment
Percentage for such date.

            Subordination Depletion Date: The Distribution Date preceding the
first Distribution Date on which the Class A Percentage (determined pursuant to
clause (ii) of the definition thereof) equals or exceeds 100%.

            Subordination Depletion Date Interest Shortfall: With respect to any
Distribution Date that occurs on or after the Subordination Depletion Date with
respect to any Unscheduled Principal Receipt (other than a Prepayment in Full or
Curtailment):

            (A)   in the case where the Applicable Unscheduled Principal Receipt
                  Period is the Mid-Month Receipt Period and such Unscheduled
                  Principal Receipt is received by the applicable Servicer on or
                  after the Determination Date in the month preceding the month
                  of such Distribution Date but prior to the first day of the
                  month of such Distribution Date, the amount of interest that
                  would have accrued at the Net Mortgage Interest Rate on the
                  amount of such Unscheduled Principal Receipt from the day of
                  its receipt or, if earlier, its application by such Servicer
                  through the last day of the month preceding the month of such
                  Distribution Date; and

            (B)   in the case where the Applicable Unscheduled Principal Receipt
                  Period is the Prior Month Receipt Period and such Unscheduled
                  Principal Receipt is received by the applicable Servicer
                  during the month preceding the month of such Distribution
                  Date, the amount of interest that would have accrued at the
                  Net Mortgage Interest Rate on the amount of such Unscheduled
                  Principal Receipt from the day of its receipt or, if earlier,
                  its application by such Servicer through the last day of the
                  month in which such Unscheduled Principal Receipt is received.

            Subservicer: Any Person that (i) services Mortgage Loans on behalf
of any Servicer, and (ii) is responsible for the performance (whether directly
or through Subservicers or Subcontractors) of a substantial portion of the
material servicing functions required to be performed under this Agreement, any
related Servicing Agreement or any sub-servicing agreement that are identified
in Item 1122(d) of Regulation AB.

            Subsidy Account: If the Trust Estate contains any Subsidy Loans, the
deposit account or accounts created and maintained by the applicable Servicer
for deposit of Subsidy Funds and amounts payable under interest subsidy
agreements relating to mortgage loans other than the Mortgage Loans.

            Subsidy Funds: If the Trust Estate contains any Subsidy Loans, funds
contributed by the employer of a Mortgagor in order to reduce the payments
required from the Mortgagor for a specified period in specified amounts.

            Subsidy Loan: Any Mortgage Loan subject to a temporary interest
subsidy agreement pursuant to which the monthly interest payments made by the
related Mortgagor will be less than the scheduled monthly interest payments on
such Mortgage Loan, with the resulting difference in interest payments being
provided by the employer of the Mortgagor.

            Substitute Mortgage Loan: As defined in Section 2.02.

            Substitution Principal Amount: With respect to any Mortgage Loan
substituted in accordance with Section 2.02 or pursuant to Section 2.03, the
excess of (x) the unpaid principal balance of the Mortgage Loan which is
substituted for over (y) the unpaid principal balance of the Substitute Mortgage
Loan, each balance being determined as of the date of substitution.

            Trust: The New York common law trust created by this Agreement which
shall be entitled "Wells Fargo Mortgage Backed Securities 2007-4 Trust."

            Trust Estate: The corpus of the Trust, consisting of the Mortgage
Loans (other than any Fixed Retained Yield), such amounts as may be held from
time to time in the Certificate Account (other than any Fixed Retained Yield) or
the Reserve Fund, the rights of the Trustee to receive the proceeds of all
insurance policies and performance bonds, if any, required to be maintained
hereunder or under the related Servicing Agreement, property which secured a
Mortgage Loan and which has been acquired by foreclosure or deed in lieu of
foreclosure, the Master Servicer's rights under the Yield Maintenance Agreement
and all other property and rights described in the first paragraph of Section
2.01(a).

            Trustee: HSBC Bank USA, National Association, a national banking
association, or any successor trustee appointed as herein provided.

            Trustee Errors and Omissions Policy: An insurance policy covering
losses caused by errors or omissions of the Trustee and its personnel.

            Type 1 Mortgage Loan: The Mortgage Loans, if any, identified as such
in the Mortgage Loan Schedule as such Mortgage Loan Schedule may be amended from
time to time in connection with a substitution pursuant to Section 2.02 or 2.03,
serviced under the Wells Fargo Bank Servicing Agreement and having a Mid-Month
Receipt Period with respect to all types of Unscheduled Principal Receipts.

            Type 2 Mortgage Loan: The Mortgage Loans, if any, identified as such
in the Mortgage Loan Schedule as such Mortgage Loan Schedule may be amended from
time to time in connection with a substitution pursuant to Section 2.02 or 2.03,
serviced under the Wells Fargo Bank Servicing Agreement and having a Prior Month
Receipt Period with respect to all types of Unscheduled Principal Receipts.

            Uncertificated Lower-Tier Interest: Any of the Class A-L1 Interest,
Class A-L5 Interest, Class A-L7 Interest, Class A-L16 Interest, Class A-LPO
Interest, Class A-LUR Interest, Class B-L1 Interest, Class B-L2 Interest, Class
B-L3 Interest, Class B-L4 Interest, Class B-L5 Interest and Class B-L6 Interest.

            Unpaid Interest Shortfalls: Each of the Class A Unpaid Interest
Shortfalls, the Class B-1 Unpaid Interest Shortfall, the Class B-2 Unpaid
Interest Shortfall, the Class B-3 Unpaid Interest Shortfall, the Class B-4
Unpaid Interest Shortfall, the Class B-5 Unpaid Interest Shortfall and the Class
B-6 Unpaid Interest Shortfall.

            Unscheduled Principal Amount: The sum for each outstanding Mortgage
Loan (including each defaulted Mortgage Loan with respect to which the related
Mortgaged Property has been acquired by the Trust Estate) of the product of (A)
the Non-PO Fraction for such Mortgage Loan and (B) the sum of the amounts
described in clauses Iy(ii) and Iy(iii) of the definition of Class A Non-PO
Optimal Principal Amount but without such amounts being multiplied by the Class
A Prepayment Percentage.

            Unscheduled Principal Receipt: Any Principal Prepayment or other
recovery of principal on a Mortgage Loan, including, without limitation, the
principal portion of Net Liquidation Proceeds, the principal portion of Net REO
Proceeds, Recoveries and proceeds received from any condemnation award or
proceeds in lieu of condemnation other than that portion of such proceeds
released to the Mortgagor in accordance with the terms of the Mortgage or
Prudent Servicing Practices, but excluding any Liquidation Profits and proceeds
of a repurchase of a Mortgage Loan by the Depositor and any Substitution
Principal Amounts.

            Unscheduled Principal Receipt Period: Either a Mid-Month Receipt
Period or a Prior Month Receipt Period.

            Upper-Tier Certificate: Any one of the Class A Certificates (other
than that portion of the Class A-R Certificate represented by the Class A-LR
Interest) and the Class B Certificates.

            Upper-Tier Certificate Account: The trust account established and
maintained pursuant to Section 4.01(e).

            Upper-Tier REMIC: One of the two separate REMICs comprising the
Trust Estate, the assets of which consist of the Uncertificated Lower-Tier
Interests and such amounts as shall from time to time be held in the Upper-Tier
Certificate Account.

            U.S. Person: As defined in Section 4.01(g).

            Voting Interest: With respect to any provisions hereof providing for
the action, consent or approval of the Holders of all Certificates evidencing
specified Voting Interests in the Trust Estate, the Class A-19 Certificates will
be entitled to 1% of the aggregate Voting Interest represented by all
Certificates and each remaining Class of Certificates will be entitled to a pro
rata portion of the remaining Voting Interest equal to the ratio obtained by
dividing the Principal Balance of such Class by the Class A Principal Balance
and the Class B Principal Balance. Each Certificateholder of a Class will have a
Voting Interest equal to the product of the Voting Interest to which such Class
is collectively entitled and the Percentage Interest in such Class represented
by such Holder's Certificates. With respect to any provisions hereof providing
for action, consent or approval of each Class of Certificates or specified
Classes of Certificates, each Certificateholder of a Class will have a Voting
Interest in such Class equal to such Holder's Percentage Interest in such Class.

            Wells Fargo Bank: Wells Fargo Bank, N.A., or its successor in
interest.

            Wells Fargo Bank Correspondents: The entities identified on a list
provided by Wells Fargo Bank to the Master Servicer, from which Wells Fargo Bank
purchased the Mortgage Loans.

            Wells Fargo Bank Servicing Agreement: The Servicing Agreement
providing for the servicing of those Mortgage Loans that are initially serviced
by Wells Fargo Bank.

            WHFIT: A "Widely Held Fixed Investment Trust" as that term is
defined in Treasury Regulations section 1.671-5(b)(22) or successor provisions.

            WHFIT Regulations: Treasury Regulations section 1.671-5, as amended.

            Yield Maintenance Agreement: The yield maintenance agreement between
the Master Servicer, on behalf of the Trust, and the Counterparty, which will be
primarily for the benefit of the Class A-5 Certificates, substantially in the
form attached hereto in Exhibit W. The Yield Maintenance Agreement shall not be
an asset of either REMIC formed under this Agreement.

            Yield Maintenance Agreement Payment: For any Distribution Date
(other than the Distribution Date in April 2007) prior to and including the
Distribution Date in May 2010, the amount, if any, required to be paid by the
Counterparty to the Master Servicer under the Yield Maintenance Agreement.

            Yield Maintenance Amount: For any Distribution Date (other than the
Distribution Date in April 2007) prior to and including the Distribution Date in
May 2010, an amount equal to the product of (a) the Principal Balance of the
Class A-5 Certificates immediately prior to such Distribution Date, (b) the
excess of (i) the lesser of (x) LIBOR and (y) 99.000% over (ii) 5.500% and (c)
one-twelfth.

            Yield Maintenance Amount Shortfall: For any Distribution Date, the
amount, if any, by which the Yield Maintenance Amount for such Distribution Date
exceeds the sum of the Yield Maintenance Agreement Payment for such Distribution
Date and any Excess Funds in the Reserve Fund.

            Section 1.02 Acts of Holders.

            (a) Any request, demand, authorization, direction, notice, consent,
waiver or other action provided by this Agreement to be given or taken by
Holders may be embodied in and evidenced by one or more instruments of
substantially similar tenor signed by such Holders in person or by an agent duly
appointed in writing. Except as herein otherwise expressly provided, such action
shall become effective when such instrument or instruments are delivered to the
Trustee. Proof of execution of any such instrument or of a writing appointing
any such agent shall be sufficient for any purpose of this Agreement and
conclusive in favor of the Trustee, if made in the manner provided in this
Section 1.02. The Trustee shall promptly notify the Master Servicer in writing
of the receipt of any such instrument or writing.

            (b) The fact and date of the execution by any Person of any such
instrument or writing may be proved by the affidavit of a witness of such
execution or by a certificate of a notary public or other officer authorized by
law to take acknowledgments of deeds, certifying that the individual signing
such instrument or writing acknowledged to him the execution thereof. When such
execution is by a signer acting in a capacity other than his or her individual
capacity, such certificate or affidavit shall also constitute sufficient proof
of his or her authority. The fact and date of the execution of any such
instrument or writing, or the authority of the individual executing the same,
may also be proved in any other manner which the Trustee deems sufficient.

            (c) The ownership of Certificates (whether or not such Certificates
shall be overdue and notwithstanding any notation of ownership or other writing
thereon made by anyone other than the Trustee and the Authenticating Agent)
shall be proved by the Certificate Register, and none of the Trustee, the
Depositor or the Master Servicer shall be affected by any notice to the
contrary.

            (d) Any request, demand, authorization, direction, notice, consent,
waiver or other action of the Holder of any Certificate shall bind every future
Holder of the same Certificate and the Holder of every Certificate issued upon
the registration of transfer thereof or in exchange therefor or in lieu thereof
in respect of anything done, omitted or suffered to be done by the Trustee, the
Depositor or the Master Servicer in reliance thereon, whether or not notation of
such action is made upon such Certificate.

            Section 1.03 Effect of Headings and Table of Contents.

            The Article and Section headings in this Agreement and the Table of
Contents are for convenience of reference only and shall not affect the
interpretation or construction of this Agreement.

            Section 1.04 Benefits of Agreement.

            Nothing in this Agreement or in the Certificates, express or
implied, shall give to any Person, other than the parties to this Agreement and
their successors hereunder and the Holders of the Certificates any benefit or
any legal or equitable right, power, remedy or claim under this Agreement.

<PAGE>

                                   ARTICLE II

                          CONVEYANCE OF MORTGAGE LOANS;
                      ORIGINAL ISSUANCE OF THE CERTIFICATES

            Section 2.01 Conveyance of Mortgage Loans.

            (a) The Depositor, concurrently with the execution and delivery
hereof, does hereby assign to the Trustee, without recourse all the right, title
and interest of the Depositor in and to (a) the Trust Estate, including all
interest (other than the portion, if any, representing the Fixed Retained Yield)
and principal received by the Depositor on or with respect to the Mortgage Loans
after the Cut-Off Date (and including scheduled payments of principal and
interest due after the Cut-Off Date but received by the Depositor on or before
the Cut-Off Date and Unscheduled Principal Receipts received or applied on the
Cut-Off Date, but not including payments of principal and interest due on the
Mortgage Loans on or before the Cut-Off Date), (b) the Insurance Policies, (c)
the obligations of the Servicers under the Servicing Agreements with respect to
the Mortgage Loans, (d) the right to receive amounts, if any, payable on behalf
of any Mortgagor from the Subsidy Account relating to any Subsidy Loan and (e)
proceeds of all the foregoing. It is agreed and understood by the Depositor and
the Trustee that it is not intended that any mortgage loan be included in the
Trust Estate that is a "High-Cost Home Loan" as defined in any of (i) the New
Jersey Home Ownership Act effective November 27, 2003, (ii) the New Mexico Home
Loan Protection Act effective January 1, 2004, (iii) the Massachusetts Predatory
Home Loan Practices Act effective November 7, 2004 or (iv) the Indiana Home Loan
Practices Act, effective January 1, 2005.

            In connection with such assignment, the Depositor shall, with
respect to each Mortgage Loan, deliver, or cause to be delivered, to the
Custodian, on or before the Closing Date the following documents or instruments
with respect to each Mortgage Loan.

            (i) The original Mortgage Note either (A) endorsed in blank or (B)
      endorsed as provided in Section 2.01(d), with all prior and intervening
      endorsements as may be necessary to show a complete chain of endorsements
      or with respect to any Mortgage Loan as to which the original Mortgage
      Note has been permanently lost or destroyed and has not been replaced, a
      lost note affidavit with a copy of the Mortgage Note and, in the case of
      any Mortgage Loan originated in the State of New York documented by a
      NYCEMA, the NYCEMA, the new Mortgage Note, if applicable, the consolidated
      Mortgage Note and the consolidated Mortgage;

            (ii) A recorded original assignment of the related Mortgage from
      Wells Fargo Bank assigning the related Mortgage to the Trustee (which may
      be assigned in blank), certified by the recording office, or, if such
      assignment is in the process of being recorded, a copy of the related
      Mortgage transmitted for recordation certified by an officer of Wells
      Fargo Bank or applicable Wells Fargo Bank Correspondent to be a true and
      correct copy of such assignment submitted for recordation; provided,
      however, if recordation is not required as described below, an assignment
      in recordable form (which may be assigned in blank) with respect to the
      related Mortgage;

            (iii) The original of each assumption agreement, modification,
      written assurance or substitution agreement pertaining to such Mortgage
      Note, if any; and

            (iv) For each Mortgage Loan secured by Co-op Shares, the originals
      of the following documents or instruments:

                  (a)   The loan security agreement;

                  (b)   The stock certificate;

                  (c)   The stock power, executed in blank;

                  (d)   The executed proprietary lease;

                  (e)   The executed recognition agreement;

                  (f)   The executed UCC-1 financing statement with evidence of
                        recording thereon; and

                  (g)   The executed UCC-3 financing statements or other
                        appropriate UCC financing statements required by state
                        law, evidencing a complete and unbroken chain from the
                        mortgagee to the Trustee with evidence of recording
                        thereon (or in a form suitable for recordation).

            (b) The Master Servicer shall promptly notify the Depositor, the
Trustee and the Custodian of the occurrence of any Document Transfer Event of
which the Master Servicer had knowledge. Following the receipt of such notice,
the Depositor shall, with respect to each Mortgage Loan, deliver, or cause to be
delivered, to the Custodian, no later than the Document Transfer Date, copies
(which may be in electronic form mutually agreed upon by the Depositor and the
Custodian) of the following additional documents or instruments with respect to
each Mortgage Loan; provided, however, that originals of such documents or
instruments shall be delivered to the Custodian if originals are required under
the law in which the related Mortgaged Property is located in order to exercise
all remedies available to the Trust under applicable law following default by
the related Mortgagor:

            (i) The original recorded Mortgage with evidence of recordation
      noted thereon or attached thereto, together with any addenda or riders
      thereto, or a copy of such recorded Mortgage with such evidence of
      recordation certified to be true and correct by the appropriate
      governmental recording office; or a copy of such recorded Mortgage with
      such evidence of recordation, or if the original Mortgage has been
      submitted for recordation but has not been returned from the applicable
      public recording office, a copy of the Mortgage certified by an officer of
      Wells Fargo Bank or the applicable Wells Fargo Bank Correspondent to be a
      true and correct copy of the original Mortgage submitted for recordation;

            (ii) The original of each assumption agreement, modification,
      written assurance or substitution agreement pertaining to such Mortgage,
      if any, or, if such document is in the process of being recorded, a copy
      of such document, certified by an officer of Wells Fargo Bank or the
      applicable Wells Fargo Bank Correspondent of such Mortgage Loan or by the
      applicable title insurance company, closing agent, settlement agent,
      escrow agent or closing attorney to be a true and correct copy of such
      document transmitted for recordation, if any;

            (iii) For each MERS Mortgage Loan that is not a MOM Mortgage Loan,
      the original assignment showing MERS as the assignee of the Mortgage, with
      evidence of recording thereon or copies thereof certified by an officer of
      Wells Fargo Bank or the applicable Wells Fargo Bank Correspondent to have
      been submitted for recordation;

            (iv) Each original recorded intervening assignment of the Mortgage
      as may be necessary to show a complete chain of title from the Mortgage
      Loan originator to Wells Fargo Bank or Wells Fargo Home Mortgage, Inc.,
      with evidence of recordation noted thereon or attached thereto, or a copy
      of such assignment with such evidence of recordation to be true and
      correct by the appropriate governmental recording office, or, if any such
      assignment has been submitted for recordation but has not been returned
      from the applicable public recording office or is not otherwise available,
      a copy of such assignment certified by an officer of Wells Fargo Bank or
      the applicable Wells Fargo Bank Correspondent to be a true and correct
      copy of the recorded assignment submitted for recordation; and

            (v) The original policy of the title insurance or certificate of
      title insurance or a written commitment to issue such a title insurance
      policy or certificate of title insurance, or a copy of such title
      insurance certified as true and correct by the applicable insurer or any
      attorney's certificate of title with an Officer's Certificate of Wells
      Fargo Bank or the applicable Wells Fargo Bank Correspondent that such
      attorney's certificate of title is customarily used in lieu of a title
      insurance policy in the jurisdiction in which the related mortgage
      property is located.

            (c) If any assignment of a Mortgage to the Trustee is in the process
of being recorded on the Closing Date, the Depositor shall use its best efforts
to cause each such original recorded document or certified copy thereof to be
delivered to the Custodian promptly following its recordation, but in no event
later than one (1) year following the Closing Date. If any Mortgage has been
recorded in the name of MERS or its designee, no assignment of Mortgage in favor
of the Trustee will be required to be prepared or delivered and instead, the
Master Servicer shall enforce any obligation of the Servicers under the
Servicing Agreements to take all actions as are necessary to cause the Trust
Estate to be shown as the owner of the related Mortgage Loan on the records of
MERS for the purpose of the system of recording transfers of beneficial
ownership of mortgages maintained by MERS. The Depositor shall also cause to be
delivered to the Custodian any other original mortgage loan document included in
the Owner Mortgage Loan File if a copy thereof has been delivered. The Depositor
shall pay from its own funds, without any right of reimbursement therefor, the
amount of any costs, liabilities and expenses incurred by the Trust Estate by
reason of the failure of the Depositor to cause to be delivered to the Custodian
within one (1) year following the Closing Date any assignment of a Mortgage
(except with respect to any Mortgage recorded in the name of MERS) not delivered
to the Custodian on the Closing Date.

            In lieu of recording an assignment of any Mortgage the Depositor
may, deliver or cause to be delivered to the Custodian the assignment of the
Mortgage Loan to the Trustee in a form suitable for recordation, if (i) with
respect to a particular state the Trustee has received an Opinion of Counsel
acceptable to it that such recording is not required to make the assignment
effective against the parties to the Mortgage or subsequent purchasers or
encumbrances of the Mortgaged Property or (ii) the Depositor has been advised by
each Rating Agency that non-recordation in a state will not result in a
reduction of the rating assigned by that Rating Agency at the time of initial
issuance of the Certificates. Set forth on Exhibit K attached hereto is a list
of all states where recordation is required by each Rating Agency to obtain the
initial ratings of the Certificates. The Custodian may rely and shall be
protected in relying upon the information contained in such Exhibit K. In the
event that the Custodian receives notice that recording is required to protect
the right, title and interest of the Trustee in and to any such Mortgage Loan
for which recordation of an assignment has not previously been required, the
Custodian shall promptly notify the Trustee and the Custodian shall, within five
Business Days (or such other reasonable period of time mutually agreed upon by
the Custodian and the Trustee) of its receipt of such notice, deliver each
previously unrecorded assignment to the related Servicer for recordation.

            (d) Except for Mortgage Notes endorsed in blank, endorsements shall
comply with the following format:

                                WITHOUT RECOURSE
                              PAY TO THE ORDER OF:

                     HSBC BANK USA, NATIONAL ASSOCIATION, AS
                     TRUSTEE under the pooling and servicing
                          agreement dated as of [date].
                         and its successors and assigns,

          [Wells Fargo Bank, N.A.] or [Wells Fargo Home Mortgage, Inc.]
                             [Signature of Officer]
                           [Officer's Name and Title]

            Except where assignments in blank are authorized or in the case of
any Mortgage registered in the name of MERS, assignments of any Mortgage shall
comply with the following:

                     HSBC BANK USA, NATIONAL ASSOCIATION, AS
                                     TRUSTEE
                         and its successors and assigns

            (e) Concurrently with the execution and delivery of this Agreement,
the Depositor shall deliver the Mortgage Loan Schedule to the Trustee, the
Master Servicer and the Custodian. The Depositor and the Master Servicer shall
provide a copy of the Mortgage Loan Schedule to any Certificateholders upon
written request made to it at the addresses set forth on Exhibit F, as the same
may be amended from time to time by written notice from such party to the other
parties hereto.

            Section 2.02 Acceptance by Custodian.

            Subject to the provisions of the following paragraph, pursuant to
the Custodial Agreement, the Custodian, on behalf of the Trustee, will declare
that it holds and will hold the documents delivered to it pursuant to Section
2.01(a) above and the other documents constituting a part of the Owner Mortgage
Loan Files or Retained Mortgage Loan Files (after the occurrence of a Document
Transfer Event) delivered to it in trust, upon the trusts herein set forth, for
the use and benefit of all present and future Certificateholders. Upon execution
of this Agreement, the Custodian will deliver to the Depositor and the Trustee
an initial certification in the form of Exhibit N hereto, to the effect that,
except as may be specified in a list of exceptions attached thereto, it has
received the original Mortgage Notes relating to each Mortgage Loan on the
Mortgage Loan Schedule.

            The Custodian will review each Owner Mortgage Loan File within 45
days after execution of this Agreement. The Custodian will deliver no later than
30 days after completion of such review to the Depositor and the Trustee a final
certification in the form of Exhibit O hereto to the effect that, except as may
be specified in a list of exceptions attached thereto, all required documents
set forth in Section 2.01(a) have been executed and received and appear regular
on their face, and that such documents relate to the Mortgage Loans identified
in the Mortgage Loan Schedule based on a comparison of the Mortgage Loan
identifying number, Mortgagor name and street address, and in so doing the
Custodian may rely on the purported due execution and genuineness of any such
document and on the purported genuineness of any signature thereon.

            If there are exceptions attached to the final certification, the
Depositor shall have a period of 60 days after the date of receipt of the final
certification within which to correct or cure any such defects. The Depositor
hereby covenants and agrees that, if any material defect is not so corrected or
cured, the Depositor will, not later than 60 days after receipt of the final
certification referred to above respecting such defects, either (i) repurchase
the related Mortgage Loan or any property acquired in respect thereof from the
Trust Estate at a price equal to the Repurchase Price or (ii) if within two
years of the Startup Day, or such other period permitted by the REMIC
Provisions, substitute for any Mortgage Loan to which such material defect
relates, a new mortgage loan (a "Substitute Mortgage Loan") having such
characteristics so that the representations and warranties of the Depositor set
forth in Section 2.03(b) hereof (other than Section 2.03(b)(i)) would not have
been incorrect had such Substitute Mortgage Loan originally been a Mortgage
Loan. In no event shall any Substitute Mortgage Loan have an unpaid principal
balance, as of the date of substitution, greater than the Scheduled Principal
Balance (reduced by the scheduled payment of principal due on the Due Date in
the month of substitution) of the Mortgage Loan for which it is substituted. In
addition, such Substitute Mortgage Loan shall have a Loan-to-Value Ratio less
than or equal to and a Net Mortgage Interest Rate equal to that of the Mortgage
Loan for which it is substituted.

            The Depositor shall determine the Repurchase Price or the
eligibility of any Substitute Mortgage Loan and the Trustee shall be protected
in relying on such determination.

            In the case of a repurchased Mortgage Loan or property, the
Repurchase Price shall be deposited by the Depositor in the Certificate Account
maintained by the Master Servicer pursuant to Section 3.01. In the case of a
Substitute Mortgage Loan, the Owner Mortgage Loan File (and Retained Mortgage
Loan File, if required pursuant to Section 2.01(b) hereof) relating thereto
shall be delivered to the Custodian and the Substitution Principal Amount (if
any), together with (i) interest on such Substitution Principal Amount at the
applicable Net Mortgage Interest Rate to the following Due Date of such Mortgage
Loan which is being substituted for and (ii) an amount equal to the aggregate
amount of unreimbursed Periodic Advances in respect of interest previously made
by the applicable Servicer, the Master Servicer or the Trustee with respect to
such Mortgage Loan, shall be deposited in the Certificate Account. The Monthly
Payment on the Substitute Mortgage Loan for the Due Date in the month of
substitution shall not be part of the Trust Estate. Upon receipt by the
Custodian of a Request for Release signed by an officer of the Depositor, the
Custodian shall release to the Depositor the Owner Mortgage Loan File (and
Retained Mortgage Loan File, if applicable) of the Mortgage Loan being removed.
The Trustee shall execute and deliver such instrument of transfer or assignment
(or, in the case of a Mortgage Loan registered in the name of MERS or its
designee, the Master Servicer shall enforce the obligation of the applicable
Servicer under the related Servicing Agreement to take all necessary action to
reflect such assignment on the records of MERS), in each case without recourse,
as shall be necessary to vest in the Depositor legal and beneficial ownership of
such substituted or repurchased Mortgage Loan or property. It is understood and
agreed that the obligation of the Depositor to substitute a new Mortgage Loan
for or repurchase any Mortgage Loan or property as to which such a material
defect in a constituent document exists shall constitute the sole remedy
respecting such defect available to the Certificateholders or the Trustee on
behalf of the Certificateholders. The failure of the Custodian to give the final
certification or the Trustee to give any notice within the required time periods
shall not affect or relieve the Depositor's obligation to repurchase any
Mortgage Loan pursuant to this Section 2.02.

            The Trustee shall be responsible for enforcing the Depositor's
obligations under this Section 2.02. If the Trustee receives written notice from
the Custodian or the Master Servicer that the defect is not cured by the
Depositor within 60 days after the Trustee's notice, the Trustee shall enforce
the Depositor's obligation to repurchase such Mortgage Loan or substitute for
such Mortgage Loan in accordance with the provisions of this Section 2.02. In
connection with any substitution permitted by this Section 2.02, the Master
Servicer shall verify that the unpaid principal balance and the Loan-to-Value
Ratio of the Substitute Mortgage Loan satisfy the requirements of this Section
2.02.

            The Master Servicer is hereby directed to execute and deliver, on
behalf of the Trust, the Yield Maintenance Agreement.

            Section 2.03 Representations and Warranties of the Master Servicer
and the Depositor.

            (a) The Master Servicer hereby represents and warrants to the
Trustee for the benefit of the Certificateholders that, as of the date of
execution of this Agreement:

            (i) The Master Servicer is a national banking association duly
      chartered and validly existing in good standing under the laws of the
      United States;

            (ii) The execution and delivery of this Agreement by the Master
      Servicer and its performance and compliance with the terms of this
      Agreement will not violate the Master Servicer's corporate charter or
      by-laws or constitute a default (or an event which, with notice or lapse
      of time, or both, would constitute a default) under, or result in the
      breach of, any material contract, agreement or other instrument to which
      the Master Servicer is a party or which may be applicable to the Master
      Servicer or any of its assets;

            (iii) This Agreement, assuming due authorization, execution and
      delivery by the Trustee and the Depositor, constitutes a valid, legal and
      binding obligation of the Master Servicer, enforceable against it in
      accordance with the terms hereof subject to applicable bankruptcy,
      insolvency, reorganization, moratorium and other laws affecting the
      enforcement of creditors' rights generally and to general principles of
      equity, regardless of whether such enforcement is considered in a
      proceeding in equity or at law;

            (iv) The Master Servicer is not in default with respect to any order
      or decree of any court or any order, regulation or demand of any federal,
      state, municipal or governmental agency, which default might have
      consequences that would materially and adversely affect the condition
      (financial or other) or operations of the Master Servicer or its
      properties or might have consequences that would materially affect its
      performance hereunder;

            (v) Except as otherwise disclosed in the Prospectus, no legal or
      governmental proceedings are pending (or known to be contemplated) against
      the Master Servicer that would be material to Certificateholders;

            (vi) Except as otherwise disclosed in the Prospectus, the Master
      Servicer is not aware and has not received notice that any default, early
      amortization or other performance triggering event has occurred as to any
      other securitization due to any act or failure to act of the Master
      Servicer under such securitization;

            (vii) Except as otherwise disclosed in the Prospectus, the Master
      Servicer has not been terminated as master servicer in a residential
      mortgage loan securitization, either due to a master servicing default or
      to application of a master servicing performance test or trigger;

            (viii) Except as otherwise disclosed in the Prospectus or otherwise
      in writing provided by the Master Servicer to the Depositor, there has
      been no material noncompliance with the applicable servicing criteria with
      respect to other securitizations of residential mortgage loans involving
      the Master Servicer as a master servicer within the past three (3) years;

            (ix) Except as otherwise disclosed in the Prospectus, no material
      changes to the Master Servicer's policies or procedures with respect to
      the master servicing function it will perform under this Agreement for
      mortgage loans of a type similar to the Mortgage Loans have occurred
      during the three-year period immediately preceding the date of this
      Agreement;

            (x) Except as otherwise disclosed in the Prospectus, there is no
      material risk that the Master Servicer's financial condition could affect
      one or more aspects of the performance by the Master Servicer of its
      master servicing obligations under this Agreement in a manner that could
      have a material impact on the performance of the Mortgage Loans or the
      Certificates; and

            (xi) Except as disclosed in the Prospectus, there are no
      affiliations, relationships or transactions relating to the Master
      Servicer and any party identified in Item 1119 of Regulation AB of the
      type described therein.

            It is understood and agreed that the representations and warranties
set forth in this Section 2.03(a) shall survive delivery of the respective Owner
Mortgage Loan Files to the Trustee or the Custodian. Upon discovery by any of
the Depositor, the Master Servicer or the Trustee of a breach of any of the
representations and warranties set forth in this Section 2.03(a), the party
discovering such breach shall give prompt written notice, which shall not exceed
two days, to the other parties. The Master Servicer shall consult with the
Depositor to determine if any such breach is material and any breach determined
by the Depositor to be material shall be included by the Master Servicer on the
next Distribution Date Statement prepared pursuant to Section 4.04.

            (b) The Depositor hereby represents and warrants to the Trustee for
the benefit of Certificateholders that, as of the date of execution of this
Agreement, with respect to the Mortgage Loans, or each Mortgage Loan, as the
case may be:

            (i) The information set forth in the Mortgage Loan Schedule was true
      and correct in all material respects at the date or dates respecting which
      such information is furnished as specified in the Mortgage Loan Schedule;

            (ii) Immediately prior to the transfer and assignment contemplated
      herein, the Depositor was the sole owner and holder of the Mortgage Loan
      free and clear of any and all liens, pledges, charges or security
      interests of any nature and has full right and authority to sell and
      assign the same;

            (iii) The Mortgage is a valid, subsisting and enforceable first lien
      on the property therein described, and the Mortgaged Property is free and
      clear of all encumbrances and liens having priority over the first lien of
      the Mortgage except for liens for real estate taxes and special
      assessments not yet due and payable and liens or interests arising under
      or as a result of any federal, state or local law, regulation or ordinance
      relating to hazardous wastes or hazardous substances, and, if the related
      Mortgaged Property is a condominium unit, any lien for common charges
      permitted by statute or homeowners association fees; and if the Mortgaged
      Property consists of shares of a cooperative housing corporation, any lien
      for amounts due to the cooperative housing corporation for unpaid
      assessments or charges or any lien of any assignment of rents or
      maintenance expenses secured by the real property owned by the cooperative
      housing corporation; and any security agreement, chattel mortgage or
      equivalent document related to, and delivered to the Trustee or to the
      Custodian with, any Mortgage establishes in the Depositor a valid and
      subsisting first lien on the property described therein and the Depositor
      has full right to sell and assign the same to the Trustee;

            (iv) Neither the Depositor nor any prior holder of the Mortgage or
      the related Mortgage Note has modified the Mortgage or the related
      Mortgage Note in any material respect, satisfied, canceled or subordinated
      the Mortgage in whole or in part, released the Mortgaged Property in whole
      or in part from the lien of the Mortgage, or executed any instrument of
      release, cancellation, modification or satisfaction, except in each case
      as is reflected in an agreement delivered to the Trustee or the Custodian
      pursuant to Section 2.01(a);

            (v) All taxes, governmental assessments, insurance premiums, and
      water, sewer and municipal charges, which previously became due and owing
      have been paid, or an escrow of funds has been established, to the extent
      permitted by law, in an amount sufficient to pay for every such item which
      remains unpaid; and the Depositor has not advanced funds, or received any
      advance of funds by a party other than the Mortgagor, directly or
      indirectly (except pursuant to any Subsidy Loan arrangement) for the
      payment of any amount required by the Mortgage, except for interest
      accruing from the date of the Mortgage Note or date of disbursement of the
      Mortgage Loan proceeds, whichever is later, to the day which precedes by
      thirty days the first Due Date under the related Mortgage Note;

            (vi) The Mortgaged Property is undamaged by water, fire, earthquake,
      earth movement other than earthquake, windstorm, flood, tornado or similar
      casualty (excluding casualty from the presence of hazardous wastes or
      hazardous substances, as to which the Depositor makes no representations),
      in a manner which would adversely affect the value of the Mortgaged
      Property as security for the Mortgage Loan or the use for which the
      premises were intended and to the best of the Depositor's knowledge, there
      is no proceeding pending or threatened for the total or partial
      condemnation of the Mortgaged Property;

            (vii) The Mortgaged Property is free and clear of all mechanics' and
      materialmen's liens or liens in the nature thereof; provided, however,
      that this warranty shall be deemed not to have been made at the time of
      the initial issuance of the Certificates if a title policy affording, in
      substance, the same protection afforded by this warranty is furnished to
      the Trustee by the Depositor;

            (viii) Except for Mortgage Loans secured by Co-op Shares and
      Mortgage Loans secured by residential long-term leases, the Mortgaged
      Property consists of a fee simple estate in real property; all of the
      improvements which are included for the purpose of determining the
      appraised value of the Mortgaged Property lie wholly within the boundaries
      and building restriction lines of such property and no improvements on
      adjoining properties encroach upon the Mortgaged Property (unless insured
      against under the related title insurance policy); and to the best of the
      Depositor's knowledge, the Mortgaged Property and all improvements thereon
      comply with all requirements of any applicable zoning and subdivision laws
      and ordinances;

            (ix) The Mortgage Loan meets, or is exempt from, applicable state,
      federal or local laws, regulations and other requirements, pertaining to
      usury, and the Mortgage Loan is not usurious;

            (x) To the best of the Depositor's knowledge, all inspections,
      licenses and certificates required to be made or issued with respect to
      all occupied portions of the Mortgaged Property and, with respect to the
      use and occupancy of the same, including, but not limited to, certificates
      of occupancy and fire underwriting certificates, have been made or
      obtained from the appropriate authorities;

            (xi) All payments required to be made up to the Due Date immediately
      preceding the Cut-Off Date for such Mortgage Loan under the terms of the
      related Mortgage Note have been made and no Mortgage Loan had more than
      one delinquency in the 12 months preceding the Cut-Off Date;

            (xii) The Mortgage Note, the related Mortgage and other agreements
      executed in connection therewith are genuine, and each is the legal, valid
      and binding obligation of the maker thereof, enforceable in accordance
      with its terms, except as such enforcement may be limited by bankruptcy,
      insolvency, reorganization or other similar laws affecting the enforcement
      of creditors' rights generally and by general equity principles
      (regardless of whether such enforcement is considered in a proceeding in
      equity or at law); and, to the best of the Depositor's knowledge, all
      parties to the Mortgage Note and the Mortgage had legal capacity to
      execute the Mortgage Note and the Mortgage and each Mortgage Note and
      Mortgage has been duly and properly executed by the Mortgagor;

            (xiii) Each Mortgage Loan at the time it was originated complied in
      all material respects with applicable federal, state and local laws
      including, without limitation, truth-in-lending, real estate settlement
      procedures, consumer credit protection, equal credit opportunity,
      predatory and abusive lending laws and disclosure laws;

            (xiv) The proceeds of the Mortgage Loans have been fully disbursed,
      there is no requirement for future advances thereunder and any and all
      requirements as to completion of any on-site or off-site improvements and
      as to disbursements of any escrow funds therefor have been complied with
      (except for escrow funds for exterior items which could not be completed
      due to weather and escrow funds for the completion of swimming pools); and
      all costs, fees and expenses incurred in making, closing or recording the
      Mortgage Loan have been paid, except recording fees with respect to
      Mortgages not recorded as of the Closing Date;

            (xv) The Mortgage Loan (except any Mortgage Loan secured by a
      Mortgaged Property located in any jurisdiction, as to which an opinion of
      counsel of the type customarily rendered in such jurisdiction in lieu of
      title insurance is instead received) is covered by an American Land Title
      Association mortgagee title insurance policy or other generally acceptable
      form of policy or insurance acceptable to Fannie Mae or Freddie Mac,
      issued by a title insurer acceptable to Fannie Mae or Freddie Mac insuring
      the originator, its successors and assigns, as to the first priority lien
      of the Mortgage in the original principal amount of the Mortgage Loan and
      subject only to (A) the lien of current real property taxes and
      assessments not yet due and payable, (B) covenants, conditions and
      restrictions, rights of way, easements and other matters of public record
      as of the date of recording of such Mortgage acceptable to mortgage
      lending institutions in the area in which the Mortgaged Property is
      located or specifically referred to in the appraisal performed in
      connection with the origination of the related Mortgage Loan, (C) liens
      created pursuant to any federal, state or local law, regulation or
      ordinance affording liens for the costs of clean-up of hazardous
      substances or hazardous wastes or for other environmental protection
      purposes and (D) such other matters to which like properties are commonly
      subject which do not individually, or in the aggregate, materially
      interfere with the benefits of the security intended to be provided by the
      Mortgage; the Depositor is the sole insured of such mortgagee title
      insurance policy, the assignment to the Trustee of the Depositor's
      interest in such mortgagee title insurance policy does not require any
      consent of or notification to the insurer which has not been obtained or
      made, such mortgagee title insurance policy is in full force and effect
      and will be in full force and effect and inure to the benefit of the
      Trustee, no claims have been made under such mortgagee title insurance
      policy, and no prior holder of the related Mortgage, including the
      Depositor, has done, by act or omission, anything which would impair the
      coverage of such mortgagee title insurance policy;

            (xvi) The Mortgaged Property securing each Mortgage Loan is insured
      by an insurer acceptable to Fannie Mae or Freddie Mac against loss by fire
      and such hazards as are covered under a standard extended coverage
      endorsement, in an amount which is not less than the lesser of 100% of the
      insurable value of the Mortgaged Property and the outstanding principal
      balance of the Mortgage Loan, but in no event less than the minimum amount
      necessary to fully compensate for any damage or loss on a replacement cost
      basis; if the Mortgaged Property is a condominium unit, it is included
      under the coverage afforded by a blanket policy for the project; if upon
      origination of the Mortgage Loan, the improvements on the Mortgaged
      Property were in an area identified in the Federal Register by the Federal
      Emergency Management Agency as having special flood hazards, a flood
      insurance policy meeting the requirements of the current guidelines of the
      Federal Insurance Administration is in effect with a generally acceptable
      insurance carrier, in an amount representing coverage not less than the
      least of (A) the outstanding principal balance of the Mortgage Loan, (B)
      the full insurable value of the Mortgaged Property and (C) the maximum
      amount of insurance which was available under the National Flood Insurance
      Act of 1968, as amended; and each Mortgage obligates the Mortgagor
      thereunder to maintain all such insurance at the Mortgagor's cost and
      expense;

            (xvii) To the best of the Depositor's knowledge, there is no
      default, breach, violation or event of acceleration existing under the
      Mortgage or the related Mortgage Note and no event which, with the passage
      of time or with notice and the expiration of any grace or cure period,
      would constitute a default, breach, violation or event of acceleration;
      the Depositor has not waived any default, breach, violation or event of
      acceleration; and no foreclosure action is currently threatened or has
      been commenced with respect to the Mortgage Loan;

            (xviii) No Mortgage Note or Mortgage is subject to any right of
      rescission, set-off, counterclaim or defense, including the defense of
      usury, nor will the operation of any of the terms of the Mortgage Note or
      Mortgage, or the exercise of any right thereunder, render the Mortgage
      Note or Mortgage unenforceable, in whole or in part, or subject it to any
      right of rescission, set-off, counterclaim or defense, including the
      defense of usury, and no such right of rescission, set-off, counterclaim
      or defense has been asserted with respect thereto;

            (xix) Each Mortgage Note (other than with respect to any Balloon
      Loans) is payable in monthly payments, resulting in complete amortization
      of the Mortgage Loan over a term of not more than 360 months;

            (xx) Each Mortgage contains customary and enforceable provisions
      such as to render the rights and remedies of the holder thereof adequate
      for the realization against the Mortgaged Property of the benefits of the
      security, including realization by judicial foreclosure (subject to any
      limitation arising from any bankruptcy, insolvency or other law for the
      relief of debtors), and there is no homestead or other exemption available
      to the Mortgagor which would interfere with such right of foreclosure;

            (xxi) To the best of the Depositor's knowledge, no Mortgagor is a
      debtor in any state or federal bankruptcy or insolvency proceeding;

            (xxii) Each Mortgaged Property is located in the United States and
      consists of a one- to four-unit residential property, which may include a
      detached home, townhouse, condominium unit or a unit in a planned unit
      development or, in the case of Mortgage Loans secured by Co-op Shares,
      leases or occupancy agreements;

            (xxiii) The Mortgage Loan is a "qualified mortgage" within the
      meaning of Section 860G(a)(3) of the Code;

            (xxiv) With respect to each Mortgage where a lost note affidavit has
      been delivered to the Custodian in place of the related Mortgage Note, the
      related Mortgage Note is no longer in existence;

            (xxv) In the event that the Mortgagor is an inter vivos "living"
      trust, (i) such trust is in compliance with Fannie Mae or Freddie Mac
      standards for inter vivos trusts and (ii) holding title to the Mortgaged
      Property in such trust will not diminish any rights as a creditor
      including the right to full title to the Mortgaged Property in the event
      foreclosure proceedings are initiated;

            (xxvi) If the Mortgage Loan is secured by a long-term residential
      lease, (1) the lessor under the lease holds a fee simple interest in the
      land; (2) the terms of such lease expressly permit the mortgaging of the
      leasehold estate, the assignment of the lease without the lessor's consent
      and the acquisition by the holder of the Mortgage of the rights of the
      lessee upon foreclosure or assignment in lieu of foreclosure or provide
      the holder of the Mortgage with substantially similar protections; (3) the
      terms of such lease do not (a) allow the termination thereof upon the
      lessee's default without the holder of the Mortgage being entitled to
      receive written notice of, and opportunity to cure, such default, (b)
      allow the termination of the lease in the event of damage or destruction
      as long as the Mortgage is in existence, (c) prohibit the holder of the
      Mortgage from being insured (or receiving proceeds of insurance) under the
      hazard insurance policy or policies relating to the Mortgaged Property or
      (d) permit any increase in rent other than pre-established increases set
      forth in the lease; (4) the original term of such lease is not less than
      15 years; (5) the term of such lease does not terminate earlier than five
      years after the maturity date of the Mortgage Note; and (6) the Mortgaged
      Property is located in a jurisdiction in which the use of leasehold
      estates in transferring ownership in residential properties is a widely
      accepted practice;

            (xxvii) No Mortgage Loan is a "high cost" loan as defined under any
      federal, state or local law applicable to such Mortgage Loan at the time
      of its origination;

            (xxviii) No Mortgage Loan is serviced by the Trustee or an affiliate
      of the Trustee; and

            (xxix) No Mortgage Loan (other than a Mortgage Loan that is a New
      Jersey covered purchase loan) is a High Cost Loan or Covered Loan, as
      applicable (as such terms are defined in the then current S&P's LEVELS(R)
      Glossary which is now Version 5.7, Appendix E) and no Mortgage Loan
      originated on or after October 1, 2002 through March 6, 2003 is governed
      by the Georgia Fair Lending Act.

            Notwithstanding the foregoing, no representations or warranties are
made by the Depositor as to the environmental condition of any Mortgaged
Property; the absence, presence or effect of hazardous wastes or hazardous
substances on any Mortgaged Property; any casualty resulting from the presence
or effect of hazardous wastes or hazardous substances on, near or emanating from
any Mortgaged Property; the impact on Certificateholders of any environmental
condition or presence of any hazardous substance on or near any Mortgaged
Property; or the compliance of any Mortgaged Property with any environmental
laws, nor is any agent, person or entity otherwise affiliated with the Depositor
authorized or able to make any such representation, warranty or assumption of
liability relative to any Mortgaged Property. In addition, no representations or
warranties are made by the Depositor with respect to the absence or effect of
fraud in the origination of any Mortgage Loan.

            It is understood and agreed that the representations and warranties
set forth in this Section 2.03(b) shall survive delivery of the respective Owner
Mortgage Loan Files (and Retained Mortgage Loan Files, if applicable) to the
Custodian and shall inure to the benefit of the Trustee notwithstanding any
restrictive or qualified endorsement or assignment.

            (c) Upon discovery by any of the Depositor, the Master Servicer, the
Trustee or the Custodian that any of the representations and warranties made in
subsection (b) above is not accurate (referred to herein as a "breach") and,
except for a breach of the representation and warranty set forth in subsection
(b)(i), where such breach is a result of the Cut-Off Date Principal Balance of a
Mortgage Loan being greater, by $1,000 or greater, than the Cut-Off Date
Principal Balance of such Mortgage Loan indicated on the Mortgage Loan Schedule,
that such breach materially and adversely affects the interests of the
Certificateholders in the related Mortgage Loan, the party discovering such
breach shall give prompt written notice (not to exceed two days after discovery)
to the other parties to this Agreement and the Custodian (any Custodian being so
obligated under a Custodial Agreement). Within 60 days of the earlier of its
discovery or its receipt of notice of any such breach, the Depositor shall cure
such breach in all material respects or shall either (i) repurchase the Mortgage
Loan or any property acquired in respect thereof from the Trust Estate at a
price equal to the Repurchase Price; provided that if the Depositor elects to
repurchase a Mortgage Loan due to a breach of the representation and warranty
set forth in subsection (b)(i), where such breach is a result of the Cut-Off
Date Principal Balance of a Mortgage Loan being greater, by $1,000 or greater,
than the Cut-Off Date Principal Balance of such Mortgage Loan indicated on the
Mortgage Loan Schedule, such repurchase is only permitted within 90 days of the
Closing Date or (ii) if within two years of the Startup Day, or such other
period permitted by the REMIC Provisions, substitute for such Mortgage Loan in
the manner described in Section 2.02. In addition to the foregoing, if a breach
of the representation set forth in clause (b)(xiii) or (xxix) of this Section
2.03 occurs as a result of a violation of an applicable predatory or abusive
lending law, the Depositor shall reimburse the Trust for all costs and damages
including, but not limited to, reasonable attorneys' fees and costs, incurred by
the Trust as a result of the violation of such law (such amount, the
"Reimbursement Amount"). The Repurchase Price, the Substitution Principal
Amount, if any, plus accrued interest thereon and the other amounts referred to
in Section 2.02, and any Reimbursement Amount shall be deposited in the
Certificate Account. It is understood and agreed, except with respect to the
second preceding sentence, that the obligation of the Depositor to repurchase or
substitute for any Mortgage Loan or property as to which such a breach has
occurred and is continuing shall constitute the sole remedy respecting such
breach available to Certificateholders or the Trustee on behalf of
Certificateholders, and such obligation shall survive until termination of the
Trust Estate hereunder.

            The Trustee shall be responsible for enforcing the Depositor's
obligations under this Section 2.03. If the Trustee receives written notice from
the Master Servicer or the Custodian that such breach is not cured by the
Depositor within 60 days after the Trustee's notice, the Trustee shall enforce
the Depositor's obligation to repurchase such Mortgage Loan or substitute for
such Mortgage Loan in accordance with the provisions of this Section 2.03. In
connection with any substitution permitted by this Section 2.03, the Master
Servicer shall verify that the unpaid principal balance and the Loan-to-Value
Ratio of the Substitute Mortgage Loan satisfy the requirements of this Section
2.03.

            Section 2.04 Execution and Delivery of Certificates.

            The Trustee acknowledges (i) the assignment to it of the Mortgage
Loans and (ii) the issuance of and hereby declares that it holds the
Uncertificated Lower-Tier Interests on behalf of the Upper-Tier REMIC and
Certificateholders. The Trustee acknowledges the delivery of the Owner Mortgage
Loan Files to the Custodian, on behalf of the Trustee. The Paying Agent,
concurrently with such delivery, has executed and delivered to or upon the order
of the Depositor, in exchange for the Mortgage Loans, together with all other
assets included in the definition of "Trust Estate," receipt of which is hereby
acknowledged, Certificates in authorized denominations which evidence ownership
of the entire Trust Estate.

            Section 2.05 Designation of Certificates; Designation of Startup Day
and Latest Possible Maturity Date.

            The Depositor hereby designates the Classes of Class A Certificates
(other than the Residual Certificate) and the Classes of Class B Certificates as
classes of "regular interests" and the Class A-R Interest as the single class of
"residual interest" in the Upper-Tier REMIC for the purposes of Code Sections
860G(a)(1) and 860G(a)(2), respectively. The Depositor hereby further designates
the Class A-L1 Interest, Class A-L5 Interest, Class A-L7 Interest, Class A-L16
Interest, Class A-LPO Interest, Class A-LUR Interest, Class B-L1 Interest, Class
B-L2 Interest, Class B-L3 Interest, Class B-L4 Interest, Class B-L5 Interest and
Class B-L6 Interest as classes of "regular interests" and the Class A-LR
Interest as the single class of "residual interest" in the Lower-Tier REMIC for
the purposes of Code Sections 860G(a)(1) and 860G(a)(2), respectively. The
Closing Date is hereby designated as the "Startup Day" of each of the Upper-Tier
REMIC and the Lower-Tier REMIC within the meaning of Code Section 860G(a)(9).
The "latest possible maturity date" of the regular interests in the Upper-Tier
REMIC and the Lower-Tier REMIC is April 27, 2037 for purposes of Code Section
860G(a)(1).

<PAGE>

                                  ARTICLE III

                  ADMINISTRATION OF THE TRUST ESTATE; SERVICING
                              OF THE MORTGAGE LOANS

            Section 3.01 Certificate Account.

            (a) The Master Servicer shall establish and maintain a Certificate
Account for the deposit of funds received by the Master Servicer with respect to
the Mortgage Loans serviced by each Servicer pursuant to each of the Servicing
Agreements. Such account shall be maintained as an Eligible Account. The Master
Servicer shall give notice to each Servicer and the Depositor of the location of
the Certificate Account and of any change in the location thereof.

            (b) The Master Servicer shall deposit into the Certificate Account
on the day of receipt thereof all amounts received by it from any Servicer
pursuant to any of the Servicing Agreements and shall, in addition, deposit into
the Certificate Account the following amounts, in the case of amounts specified
in clauses (i) and (iii), not later than the Business Day preceding the
Distribution Date on which such amounts are required to be distributed to
Certificateholders and, in the case of the amounts specified in clause (ii), not
later than the Business Day next following the day of receipt and posting by the
Master Servicer:

            (i) Periodic Advances pursuant to Section 3.03(a) made by the Master
      Servicer or the Trustee, if any and any amounts deemed received by the
      Master Servicer pursuant to Section 3.01(d);

            (ii) in the case of any Mortgage Loan that is repurchased by the
      Depositor pursuant to Section 2.02, 2.03, 3.08 or 9.01 or that is
      auctioned by the Master Servicer pursuant to Section 3.08, the purchase
      price therefor or, where applicable, any Substitution Principal Amount and
      any amounts received in respect of the interest portion of unreimbursed
      Periodic Advances; and

            (iii) any Compensating Interest for such Distribution Date.

            (c) The Master Servicer may cause the funds in the Certificate
Account to be invested in Eligible Investments. No such Eligible Investments
will be sold or disposed of at a gain prior to maturity unless the Master
Servicer has received an Opinion of Counsel or other evidence satisfactory to it
that such sale or disposition will not cause the Trust Estate to be subject to
Prohibited Transactions Tax, otherwise subject the Trust Estate to tax, or cause
either of the Upper-Tier REMIC or the Lower-Tier REMIC to fail to qualify as a
REMIC while any Certificates are outstanding. Any amounts deposited in the
Certificate Account prior to the Distribution Date may be invested for the
account of the Master Servicer and any investment income thereon shall be
additional compensation to the Master Servicer for services rendered under this
Agreement. The amount of any losses incurred in respect of any such investments
shall be deposited in the Certificate Account by the Master Servicer out of its
own funds immediately as realized, without any right of reimbursement therefor
from the Trust Estate.

            (d) For purposes of this Agreement, the Master Servicer will be
deemed to have received from a Servicer on the applicable Remittance Date for
such funds all amounts deposited by such Servicer into the Custodial P&I Account
maintained in accordance with the applicable Servicing Agreement, if such
Custodial P&I Account is not an Eligible Account as defined in this Agreement,
to the extent such amounts are not actually received by the Master Servicer on
such Remittance Date as a result of the bankruptcy, insolvency, receivership or
other financial distress of the depository institution in which such Custodial
P&I Account is being held. To the extent that amounts so deemed to have been
received by the Master Servicer are subsequently remitted to the Master
Servicer, the Master Servicer shall be entitled to retain such amounts.

            Section 3.02 Permitted Withdrawals from the Certificate Account.

            (a) The Master Servicer may, from time to time, make withdrawals
from the Certificate Account for the following purposes (limited, in the case of
Servicer reimbursements, to cases where funds in the respective Custodial P&I
Account are not sufficient therefor):

            (i) to reimburse the Master Servicer, the Trustee or any Servicer
      for Periodic Advances made by the Master Servicer or the Trustee pursuant
      to Section 3.03(a) or any Servicer pursuant to any Servicing Agreement
      with respect to previous Distribution Dates, such right to reimbursement
      pursuant to this subclause (i) being limited to amounts received on or in
      respect of particular Mortgage Loans (including, for this purpose,
      Liquidation Proceeds, REO Proceeds and proceeds from the purchase, sale,
      repurchase or substitution of Mortgage Loans pursuant to Section 2.02,
      2.03, 3.08 or 9.01) respecting which any such Periodic Advance was made;

            (ii) to reimburse any Servicer, the Master Servicer or the Trustee
      for any Periodic Advances determined in good faith to have become
      Nonrecoverable Advances; provided, however, that any portion of
      Nonrecoverable Advances representing Fixed Retained Yield shall be
      reimbursable only from amounts constituting Fixed Retained Yield and not
      from assets of the Trust Estate;

            (iii) to reimburse the Master Servicer or any Servicer from
      Liquidation Proceeds for Liquidation Expenses and for amounts expended by
      the Master Servicer or any Servicer pursuant hereto or to any Servicing
      Agreement, respectively, in good faith in connection with the restoration
      of damaged property or for foreclosure expenses;

            (iv) from any Mortgagor payment on account of interest or other
      recovery (including Net REO Proceeds) with respect to a particular
      Mortgage Loan, to pay the Master Servicing Fee with respect to such
      Mortgage Loan to the Master Servicer;

            (v) to reimburse the Master Servicer, any Servicer or the Trustee
      (or, in certain cases, the Depositor) for expenses incurred by it
      (including taxes paid on behalf of the Trust Estate) and recoverable by or
      reimbursable to it pursuant to Section 3.03(c), Section 6.03, the second
      or third paragraphs of Section 8.06 or the third sentence of Section
      8.13(a) or pursuant to such Servicer's Servicing Agreement, provided such
      expenses are "unanticipated" within the meaning of the REMIC Provisions;

            (vi) to pay to the Depositor or other purchaser with respect to each
      Mortgage Loan or property acquired in respect thereof that has been
      repurchased or replaced pursuant to Section 2.02, 2.03, 3.08 or 9.01 or
      auctioned pursuant to Section 3.08, all amounts received thereon and not
      required to be distributed as of the date on which the related repurchase
      or purchase price or Scheduled Principal Balance was determined;

            (vii) to remit funds to the Paying Agent in the amounts and in the
      manner provided for herein;

            (viii) to pay to the Master Servicer any interest earned on or
      investment income with respect to funds in the Certificate Account;

            (ix) to pay to the Master Servicer or any Servicer out of
      Liquidation Proceeds allocable to interest the amount of any unpaid Master
      Servicing Fee or Servicing Fee (as adjusted pursuant to the related
      Servicing Agreement) and any unpaid assumption fees, late payment charges
      or other Mortgagor charges on the related Mortgage Loan;

            (x) to pay to the Master Servicer as additional master servicing
      compensation any Liquidation Profits which a Servicer is not entitled to
      pursuant to the applicable Servicing Agreement;

            (xi) to withdraw from the Certificate Account any amount deposited
      in the Certificate Account that was not required to be deposited therein;

            (xii) to clear and terminate the Certificate Account pursuant to
      Section 9.01; and

            (xiii) to pay to Wells Fargo Bank from any Mortgagor payment on
      account of interest or other recovery (including Net REO Proceeds) with
      respect to a particular Mortgage Loan, the Fixed Retained Yield, if any,
      with respect to such Mortgage Loan; provided, however, that with respect
      to any payment of interest received by the Master Servicer in respect of a
      Mortgage Loan (whether paid by the Mortgagor or received as Liquidation
      Proceeds, Insurance Proceeds or otherwise) which is less than the full
      amount of interest then due with respect to such Mortgage Loan, only that
      portion of such payment of interest that bears the same relationship to
      the total amount of such payment of interest as the Fixed Retained Yield
      Rate, if any, in respect of such Mortgage Loan bears to the Mortgage
      Interest Rate shall be allocated to the Fixed Retained Yield with respect
      thereto.

            (b) The Master Servicer shall keep and maintain separate accounting,
on a Mortgage Loan by Mortgage Loan basis, for the purpose of justifying any
payment to and withdrawal from the Certificate Account. The Master Servicer
shall notify the Depositor and the Trustee of the amount, purpose and party paid
pursuant to Section 3.02(a)(v).

            Section 3.03 Advances by Master Servicer and Trustee.

            (a) In the event an Other Servicer fails to make any required
Periodic Advances of principal and interest on a Mortgage Loan as required by
the related Other Servicing Agreement prior to the Business Day preceding the
Distribution Date occurring in the month during which such Periodic Advance is
due, the Master Servicer shall make Periodic Advances to the extent provided
hereby. In the event Wells Fargo Bank in its capacity as Servicer fails to make
any required Periodic Advances of principal and interest on a Mortgage Loan as
required by the Wells Fargo Bank Servicing Agreement prior to the Business Day
preceding the Distribution Date occurring in the month during which such
Periodic Advance is due, the Trustee shall, to the extent required by Section
8.14, make such Periodic Advance to the extent provided hereby, provided that
the Trustee has previously received the certificate of the Master Servicer
described in the following sentence. The Master Servicer shall certify to the
Trustee with respect to any such Distribution Date (i) the amount of Periodic
Advances required of Wells Fargo Bank in its capacity as Servicer or such Other
Servicer, as the case may be, (ii) the amount actually advanced by Wells Fargo
Bank in its capacity as Servicer or such Other Servicer, (iii) the amount that
the Trustee or Master Servicer is required to advance hereunder and (iv) whether
the Master Servicer has determined that it reasonably believes that such
Periodic Advance is a Nonrecoverable Advance. Amounts advanced by the Trustee or
Master Servicer shall be deposited in the Certificate Account on the Business
Day preceding the related Distribution Date. Notwithstanding the foregoing,
neither the Master Servicer nor the Trustee will be obligated to make a Periodic
Advance that it reasonably believes to be a Nonrecoverable Advance. The Trustee
may conclusively rely for any determination to be made by it hereunder upon the
determination of the Master Servicer as set forth in its certificate.

            (b) To the extent an Other Servicer fails to make an advance on
account of the taxes or insurance premiums with respect to a Mortgage Loan
required pursuant to the related Other Servicing Agreement, the Master Servicer
shall, if the Master Servicer has actual knowledge of such failure of the
Servicer, advance such funds and take such steps as are necessary to pay such
taxes or insurance premiums. To the extent Wells Fargo Bank in its capacity as
Servicer fails to make an advance on account of the taxes or insurance premiums
with respect to a Mortgage Loan required pursuant to the Wells Fargo Bank
Servicing Agreement, the Master Servicer shall, if the Master Servicer knows of
such failure of Wells Fargo Bank in its capacity as Servicer, certify to the
Trustee that such failure has occurred. Upon receipt of such certification, the
Trustee shall advance such funds and take such steps as are necessary to pay
such taxes or insurance premiums.

            (c) The Master Servicer and the Trustee shall each be entitled to be
reimbursed from the Certificate Account for any Periodic Advance made by it
under Section 3.03(a) to the extent described in Section 3.02(a)(i) and (a)(ii).
The Master Servicer and the Trustee shall be entitled to be reimbursed pursuant
to Section 3.02(a)(v) for any advance by it pursuant to Section 3.03(b). The
Master Servicer shall diligently pursue restoration of such amount to the
Certificate Account from the related Servicer. The Master Servicer shall, to the
extent it has not already done so, upon the request of the Trustee, withdraw
from the Certificate Account and remit to the Trustee any amounts to which the
Trustee is entitled as reimbursement pursuant to Section 3.02 (a)(i), (ii) and
(v).

            (d) Except as provided in Section 3.03(a) and (b), neither the
Master Servicer nor the Trustee shall be required to pay or advance any amount
which any Servicer was required, but failed, to deposit in the Certificate
Account.

            Section 3.04 Custodian to Cooperate; Release of Owner Mortgage Loan
Files and Retained Mortgage Loan Files.

            In connection with the deposit by a Servicer into the Certificate
Account of the proceeds from a Liquidated Loan or of a Prepayment in Full, the
Master Servicer or applicable Servicer shall confirm that all amounts required
to be remitted to the Certificate Account in connection with such Mortgage Loan
have been so deposited, and the Master Servicer or applicable Servicer shall
deliver two copies of any related Request for Release to the Custodian. The
Custodian shall, within five Business Days of its receipt of such a Request for
Release, release the related Owner Mortgage Loan File (and Retained Mortgage
Loan File, if applicable) to the Master Servicer or such Servicer, as requested
by the Master Servicer or such Servicer. No expenses incurred in connection with
any instrument of satisfaction or deed of reconveyance shall be chargeable to
the Certificate Account.

            From time to time and as appropriate for the servicing or
foreclosure of any Mortgage Loan, including but not limited to, collection under
any insurance policies, or to effect a partial release of any Mortgaged Property
from the lien of the Mortgage, the Servicer of such Mortgage Loan shall deliver
to the Master Servicer or Custodian two copies of a Request for Release. Upon
the Master Servicer's receipt of any such Request for Release, the Master
Servicer shall promptly forward such request in hard copy or in electronic
format acceptable to the Custodian. The Custodian shall, within five Business
Days, release the related Owner Mortgage Loan File (and Retained Mortgage Loan
File, if applicable) to the Master Servicer or such Servicer. Any such Request
for Release shall obligate the Master Servicer or such Servicer, as the case may
be, to return the Owner Mortgage Loan File (and Retained Mortgage Loan File, if
applicable) to the Custodian by the sixtieth day following the release thereof,
unless (i) the Mortgage Loan has been liquidated and the Liquidation Proceeds
relating to the Mortgage Loan have been deposited in the Certificate Account or
(ii) the Owner Mortgage Loan File (and Retained Mortgage Loan File, if
applicable) or such document has been delivered to an attorney, or to a public
trustee or other public official as required by law, for purposes of initiating
or pursuing legal action or other proceedings for the foreclosure of the
Mortgaged Property either judicially or non-judicially. Upon receipt of two
copies of a Request for Release stating that such Mortgage Loan was liquidated
and that all amounts received or to be received in connection with such
liquidation which are required to be deposited into the Certificate Account have
been so deposited, or that such Mortgage Loan has become an REO Mortgage Loan,
the Custodian shall amend its records.

            Upon the occurrence of the event specified in clause (ii) of the
preceding paragraph, the Trustee shall execute and deliver to the Master
Servicer or such Servicer, as directed by the Master Servicer, court pleadings,
requests for trustee's sale or other documents necessary to the foreclosure or
trustee's sale in respect of a Mortgaged Property or to any legal action brought
to obtain judgment against any Mortgagor on the Mortgage Note or Mortgage or to
obtain a deficiency judgment, or to enforce any other remedies or rights
provided by the Mortgage Note or Mortgage or otherwise available at law or in
equity. Each such certification shall include a request that such pleadings or
documents be executed by the Trustee and a statement as to the reason such
documents or pleadings are required and that the execution and delivery thereof
by the Trustee will not invalidate or otherwise affect the lien of the Mortgage,
except for the termination of such a lien upon completion of the foreclosure
proceeding or trustee's sale.

            Section 3.05 Annual Compliance Statements.

            The Master Servicer shall deliver in electronic form, or otherwise
make available to the Depositor and the Trustee, and the Master Servicer shall
cause each Additional Master Servicer engaged by it and each Servicer to
deliver, in electronic form, or otherwise make available, to the Master
Servicer, the Trustee and each Rating Agency on or before March 5 of each year
or if such day is not a Business Day, the next Business Day (with a 10 calendar
day cure period, but in no event later than March 15), commencing in March 2008,
a copy of a certificate (followed by a hard copy to the party or parties
receiving such certificate within 10 calendar days) in the form required by Item
1123 of Regulation AB, to the effect that (i) an authorized officer of the
Master Servicer, the Additional Master Servicer or the applicable Servicer, as
the case may be, has reviewed (or a review has been made under his or her
supervision of) such party's activities under this Agreement or the applicable
Servicing Agreement, in the case of a Servicer, or such other applicable
agreement in the case of an Additional Master Servicer, during the prior
calendar year or portion thereof and (ii) to the best of such officer's
knowledge, based on such review, such party has fulfilled all of its obligations
under this Agreement or the applicable Servicing Agreement, in the case of a
Servicer, or such other applicable agreement in the case of an Additional Master
Servicer, in all material respects throughout the prior calendar year or portion
thereof or, if there has been a failure to fulfill any such obligation in any
material respect, specifying each such failure known to such officer and the
nature and status thereof. If any of the certificates delivered pursuant to this
Section 3.05 disclose that there has been a failure to fulfill any obligation in
any material respect then the Master Servicer shall promptly notify the
Depositor and forward a copy of such certificate to the Depositor, and the
Depositor shall review such certificate and, if applicable, consult with the
Master Servicer as to the nature of any failure to fulfill any obligation under
this Agreement or the applicable Servicing Agreement, in the case of a Servicer,
or such other applicable agreement in the case of an Additional Master Servicer,
in any material respect.

            Section 3.06 Title, Management and Disposition of Any REO Mortgage
Loan.

            The Master Servicer shall enforce the obligations of the applicable
Servicer to administer each REO Mortgage Loan at all times so that each REO
Mortgage Loan qualifies as "foreclosure property" under the REMIC Provisions and
that it does not earn any "net income from foreclosure property" which is
subject to tax under the REMIC Provisions. In the event that a Servicer is
unable to dispose of any REO Mortgage Loan within the period mandated by each of
the Servicing Agreements, the Master Servicer shall monitor such Servicer to
verify that such REO Mortgage Loan is auctioned to the highest bidder within the
period so specified. In the event of any such sale of a REO Mortgage Loan, the
Custodian shall, at the written request of the Master Servicer and upon being
supported with appropriate forms therefor, within five Business Days of the
deposit by the Master Servicer of the proceeds of such sale or auction into the
Certificate Account, release or cause to be released to the entity identified by
the Master Servicer the related Owner Mortgage Loan File, Retained Mortgage Loan
File, if applicable, and Servicer Mortgage Loan File and shall execute and
deliver such instruments of transfer or assignment, in each case without
recourse, as shall be necessary to vest in the auction purchaser title to the
REO Mortgage Loan and the Custodian shall have no further responsibility with
regard to such Owner Mortgage Loan File, Retained Mortgage Loan File, if
applicable, or Servicer Mortgage Loan File. Neither the Trustee, the Master
Servicer nor any Servicer, acting on behalf of the Trust Estate, shall provide
financing from the Trust Estate to any purchaser of an REO Mortgage Loan.

            Section 3.07 Amendments to Servicing Agreements, Modification of
Standard Provisions.

            (a) Subject to the prior written consent of the Trustee pursuant to
Section 3.07(b) and the prior written consent of the Depositor, the Master
Servicer may, from time to time, to the extent permitted by the applicable
Servicing Agreement, make such modifications and amendments to such Servicing
Agreement as the Master Servicer deems necessary or appropriate to confirm or
carry out more fully the intent and purpose of such Servicing Agreement and the
duties, responsibilities and obligations to be performed by the applicable
Servicer thereunder. Such modifications may only be made if they are consistent
with the REMIC Provisions, as evidenced by an Opinion of Counsel. Prior to the
issuance of any modification or amendment, the Master Servicer shall deliver to
the Trustee and the Depositor such Opinion of Counsel and an Officer's
Certificate setting forth (i) the provision that is to be modified or amended,
(ii) the modification or amendment that the Master Servicer desires to issue and
(iii) the reason or reasons for such proposed amendment or modification.

            (b) The Trustee shall consent to any amendment or supplement to a
Servicing Agreement proposed by the Master Servicer pursuant to Section 3.07(a),
which consent and amendment shall not require the consent of any
Certificateholder if it is (i) for the purpose of curing any mistake or
ambiguity, to further effect or protect the rights of the Certificateholders or
(ii) for any other purpose, provided such amendment or supplement for such other
purpose cannot reasonably be expected to adversely affect Certificateholders.
The lack of reasonable expectation of an adverse effect on Certificateholders
may be established through the delivery to the Trustee of (i) an Opinion of
Counsel to such effect or (ii) written notification from each Rating Agency to
the effect that such amendment or supplement will not result in reduction of the
current rating assigned by that Rating Agency to the Certificates.
Notwithstanding the two immediately preceding sentences, the Trustee may, in its
discretion, decline to enter into or consent to any such supplement or amendment
if its own rights, duties or immunities shall be adversely affected.

            (c)(i) Notwithstanding anything to the contrary in this Section
3.07, the Master Servicer from time to time may, without the consent of any
Certificateholder or the Trustee, enter into an amendment (A) to an Other
Servicing Agreement for the purpose of (i) eliminating or reducing Month End
Interest and (ii) providing for the remittance of Full Unscheduled Principal
Receipts by the applicable Servicer to the Master Servicer not later than the
24th day of each month (or if such day is not a Business Day, on the previous
Business Day), (B) to the Wells Fargo Bank Servicing Agreement for the purpose
of changing the applicable Remittance Date to the 18th day of each month (or if
such day is not a Business Day, on the previous Business Day) or (C) to a
Servicing Agreement for the purpose of effecting or facilitating compliance by
the applicable Servicer with Regulation AB or to conform a Servicing Agreement
to industry practices relating to Regulation AB.

            (ii) The Master Servicer may direct Wells Fargo Bank in its capacity
as Servicer to enter into an amendment to the Wells Fargo Bank Servicing
Agreement for the purposes described in Section 3.07(c)(i)(B) or (C).

            Section 3.08 Oversight of Servicing.

            The Master Servicer shall supervise, monitor and oversee the
servicing of the Mortgage Loans by each Servicer and the performance by each
Servicer of all services, duties, responsibilities and obligations (including
the obligation to maintain an Errors and Omissions Policy and Fidelity Bond)
that are to be observed or performed by the Servicer under its respective
Servicing Agreement. In performing its obligations hereunder, the Master
Servicer shall act in a manner consistent with Accepted Master Servicing
Practices and in a manner consistent with the terms and provisions of any
insurance policy required to be maintained by the Master Servicer or any
Servicer pursuant to this Agreement or any Servicing Agreement. The Master
Servicer acknowledges that prior to taking certain actions required to service
the Mortgage Loans, each Servicing Agreement provides that the Servicer
thereunder must notify, consult with, obtain the consent of, waiver from, or
otherwise follow the instructions of the Master Servicer. In the case of any
request for waiver from a Servicer, the Master Servicer shall promptly instruct
such Servicer or otherwise respond to such Servicer's request. The Master
Servicer shall not waive compliance by a Servicer with those provisions of its
Servicing Agreement which are required to enable the Depositor and the Master
Servicer to satisfy the Trust's ongoing reporting obligations under the Exchange
Act. In addition, in no event will the Master Servicer instruct such Servicer to
take any action, give any consent to action by such Servicer or waive compliance
by such Servicer with any provision of such Servicer's Servicing Agreement if
any resulting action or failure to act would be inconsistent with the
requirements of the Rating Agencies that rated the Certificates, would be
inconsistent with the requirements of Regulation AB or would otherwise have an
adverse effect on the Certificateholders. Any such action or failure to act
shall be deemed to have an adverse effect on the Certificateholders if such
action or failure to act either results in (i) the downgrading of the rating
assigned by any Rating Agency to the Certificates, (ii) the loss by the
Upper-Tier REMIC or the Lower-Tier REMIC of REMIC status for federal income tax
purposes or (iii) the imposition of any Prohibited Transaction Tax or any
federal taxes on any of the Upper-Tier REMIC, the Lower-Tier REMIC or the Trust
Estate. The Master Servicer shall have full power and authority in its sole
discretion to take any action with respect to the Trust Estate as may be
necessary or advisable to avoid the circumstances specified including clause
(ii) or (iii) of the preceding sentence.

            For the purposes of determining whether any modification of a
Mortgage Loan shall be permitted by the Master Servicer, such modification shall
be construed as a substitution of the modified Mortgage Loan for the Mortgage
Loan originally deposited in the Trust Estate if it would be a "significant
modification" within the meaning of Section 1.860G-2(b) of the regulations of
the U.S. Department of the Treasury. No modification shall be approved unless
(i) the modified Mortgage Loan would qualify as a Substitute Mortgage Loan under
Section 2.02 and (ii) with respect to any modification that occurs more than
three months after the Closing Date and is not the result of a default or a
reasonably foreseeable default under the Mortgage Loan, there is delivered to
the Trustee an Opinion of Counsel (at the expense of the party seeking to modify
the Mortgage Loan) to the effect that such modification would not be treated as
giving rise to a new debt instrument for federal income tax purposes as
described in the preceding sentence; provided, however, that no such Opinion of
Counsel need be delivered if the sole purpose of the modification is to reduce
the Monthly Payment on a Mortgage Loan as a result of a Curtailment such that
the Mortgage Loan is fully amortized by its original maturity date.

            During the term of this Agreement, the Master Servicer shall consult
fully with each Servicer as may be necessary from time to time to perform and
carry out the Master Servicer's obligations hereunder and otherwise exercise
reasonable efforts to cause such Servicer to perform and observe the covenants,
obligations and conditions to be performed or observed by it under its Servicing
Agreement.

            The relationship of the Master Servicer to the Trustee under this
Agreement is intended by the parties to be that of an independent contractor and
not that of a joint venturer, partner or agent.

            The Master Servicer shall administer the Trust Estate on behalf of
the Trustee and shall have full power and authority, acting alone or (subject to
the requirements of Section 6.06) through one or more Subcontractors, to do any
and all things in connection with such administration which it may deem
necessary or desirable. Upon the execution and delivery of this Agreement, and
from time to time as may be required thereafter, the Trustee shall furnish the
Master Servicer or its Subcontractors with any powers of attorney and such other
documents as may be necessary or appropriate to enable the Master Servicer to
carry out its administrative duties hereunder.

            The Depositor shall have a limited option to repurchase any
defaulted Mortgage Loan or REO Mortgage Loan during the following time periods:
(i) beginning on the first day of the second month following the month in which
the Master Servicer has reported that a Servicer has initiated foreclosure
proceedings with respect to such a defaulted Mortgage Loan, with such repurchase
option expiring on the last day of such second following month; (ii) beginning
on the first day of the second month following the month in which the Master
Servicer has reported that such defaulted Mortgage Loan has become an REO
Mortgage Loan, with such repurchase option expiring on the last day of such
second following month; and (iii) beginning on the day on which a Servicer
accepts a contractual commitment by a third party to purchase the Mortgaged
Property related to the defaulted Mortgage Loan or REO Mortgage Loan, with such
repurchase option expiring on the earlier of the last day of the month in which
such contractual commitment was accepted by the Servicer or the day immediately
prior to the day on which the closing occurs with respect to such third party
purchase of the Mortgaged Property related to the defaulted Mortgage Loan or REO
Mortgage Loan. The Depositor shall be entitled to repurchase at its option any
Mortgage Loan in the Trust Estate which, pursuant to paragraph 5(b) of the
Mortgage Loan Purchase Agreement, Wells Fargo Bank requests the Depositor to
repurchase and to sell to Wells Fargo Bank to facilitate the exercise of Wells
Fargo Bank's rights against the originator or a prior holder of such Mortgage
Loan. The purchase price for any Mortgage Loan repurchased pursuant to this
paragraph shall be the Repurchase Price. Upon the receipt of such Repurchase
Price, the Master Servicer shall provide to the Trustee the certification
required by Section 3.04 and the Trustee and the Custodian, if any, shall
promptly release to the Depositor the Owner Mortgage Loan File and Retained
Mortgage Loan File, if applicable, relating to the Mortgage Loan being
repurchased.

            In the event that (i) the Master Servicer determines at any time
that, notwithstanding the representations and warranties set forth in Section
2.03(b), any Mortgage Loan is not a "qualified mortgage" within the meaning of
Section 860G of the Code and (ii) the Trustee is unable to enforce the
obligation of the Depositor to purchase such Mortgage Loan pursuant to Section
2.02 within two months of such determination, the Master Servicer shall cause
such Mortgage Loan to be auctioned to the highest bidder and sold out of the
Trust Estate no later than the date 90 days after such determination. In the
event of any such sale of a Mortgage Loan, the Custodian shall, at the written
request of the Master Servicer and upon being supported with appropriate forms
therefor, within five Business Days of the deposit by the Master Servicer of the
proceeds of such auction into the Certificate Account, release or cause to be
released to the entity identified by the Master Servicer the related Owner
Mortgage Loan File, Retained Mortgage Loan File, if applicable, and Servicer
Mortgage Loan File and shall execute and deliver such instruments of transfer or
assignment, in each case without recourse, as shall be necessary to vest in the
auction purchaser title to the Mortgage Loan and the Custodian shall have no
further responsibility with regard to such Owner Mortgage Loan File, Retained
Mortgage Loan File, if applicable, or Servicer Mortgage Loan File. None of the
Trustee, the Custodian, the Master Servicer or any Servicer, acting on behalf of
the Trustee, shall provide financing from the Trust Estate to any purchaser of a
Mortgage Loan.

            The Master Servicer, on behalf of the Trustee, shall, pursuant to
the Servicing Agreements, object to the foreclosure upon, or other related
conversion of the ownership of, any Mortgaged Property by the related Servicer
if (i) the Master Servicer believes such Mortgaged Property may be contaminated
with or affected by hazardous wastes or hazardous substances or (ii) such
Servicer does not agree to administer such Mortgaged Property, once the related
Mortgage Loan becomes an REO Mortgage Loan, in a manner which would not result
in a federal tax being imposed upon the Trust Estate or the Upper-Tier REMIC or
the Lower-Tier REMIC.

            At the direction of the Depositor, the Master Servicer may enter
into a special servicing agreement with an unaffiliated holder of 100%
Percentage Interest of a Class of Class B Certificates or a holder of a class of
securities representing interests in the Class B Certificates and/or other
subordinated mortgage pass-through certificates (such entity, a "Special
Servicer"), such agreement (a "Special Servicing Agreement") to be substantially
in the form of Exhibit M hereto or subject to each Rating Agency's
acknowledgment that the ratings of the Certificates in effect immediately prior
to the entering into of such agreement would not be qualified, downgraded or
withdrawn and the Certificates would not be placed on credit review status
(except for possible upgrading) as a result of such agreement. Any such
agreement may contain provisions whereby such holder may (a) purchase any
Mortgage Loans that are more than 180 days delinquent and (b) instruct the
Master Servicer to instruct a Servicer to the extent provided in the applicable
Servicing Agreement to commence or delay foreclosure proceedings with respect to
delinquent Mortgage Loans and will contain provisions for the deposit of cash by
the holder that would be available for distribution to Certificateholders if
Liquidation Proceeds are less than they otherwise may have been had the Servicer
acted in accordance with its normal procedures.

            The Master Servicer shall monitor the rating of Wells Fargo &
Company and upon the occurrence of a Document Transfer Event relating to such
rating, shall promptly notify the Depositor, Trustee and Custodian of the
occurrence of such Document Transfer Event.

            Section 3.09 Termination and Substitution of Servicing Agreements.

            Upon the occurrence of any event for which a Servicer may be
terminated pursuant to its Servicing Agreement, the Master Servicer shall
promptly deliver to the Depositor and the Trustee an Officer's Certificate
certifying that an event has occurred which may justify termination of such
Servicing Agreement, describing the circumstances surrounding such event and
recommending what action should be taken by the Trustee with respect to such
Servicer. If the Master Servicer recommends that such Servicing Agreement be
terminated, the Master Servicer's certification must state that the breach is
material and not merely technical in nature. Based upon such certification, the
Master Servicer, or if provided by the applicable Other Servicing Agreement and
upon written direction of the Master Servicer, the Trustee, shall promptly
terminate such Other Servicing Agreement. The Trustee shall terminate the Wells
Fargo Bank Servicing Agreement in accordance with the provisions of Article 19
thereof. The Master Servicer shall indemnify the Trustee and hold it harmless
from and against any and all claims, liabilities, costs and expenses (including,
without limitation, reasonable attorneys' fees) arising out of, or assessed
against the Trustee in connection with termination of a Servicing Agreement at
the direction of the Master Servicer except to the extent that such claims,
liabilities, costs and expenses are incurred as a result of the bad faith,
willful misfeasance or gross negligence of the Trustee in the performance of its
obligations hereunder. To the extent that the costs and expenses (including any
amounts paid by the Master Servicer pursuant to the immediately preceding
sentence) of the Master Servicer related to any termination of an Other
Servicer, appointment of a successor servicer to an Other Servicer or the
transfer and assumption of servicing by the Master Servicer with respect to any
Other Servicing Agreement (including, without limitation, (i) all legal costs
and expenses and all due diligence costs and expenses associated with an
evaluation of the potential termination of an Other Servicer as a result of an
event of default by such Other Servicer, (ii) all costs and expenses associated
with the complete transfer of servicing, including all servicing files and all
servicing data and the completion, correction or manipulation of such servicing
data as may be required by the successor servicer to correct any errors or
insufficiencies in the servicing data or otherwise to enable the successor
servicer to service the Mortgage Loans in accordance with the related Other
Servicing Agreement and (iii) any costs incurred by the Trustee in connection
with a servicing transfer) are not fully and timely reimbursed by the terminated
Other Servicer, the Master Servicer shall be entitled to reimbursement of such
costs and expenses from the Certificate Account. To the extent that the costs
and expenses of the Trustee related to any termination of Wells Fargo Bank, as a
Servicer under the Wells Fargo Bank Servicing Agreement, appointment of a
successor to Wells Fargo Bank as a Servicer or the transfer and assumption of
servicing by the Trustee with respect to the Wells Fargo Bank Servicing
Agreement (including, without limitation, (i) all legal costs and expenses and
all due diligence costs and expenses associated with an evaluation of the
potential termination of Wells Fargo Bank as a Servicer as a result of an event
of default by Wells Fargo Bank as Servicer and (ii) all costs and expenses
associated with the complete transfer of servicing, including all servicing
files and all servicing data and the completion, correction or manipulation of
such servicing data as may be required by the successor servicer to correct any
errors or insufficiencies in the servicing data or otherwise to enable the
successor servicer to service the Mortgage Loans in accordance with the Wells
Fargo Bank Servicing Agreement) are not fully and timely reimbursed by Wells
Fargo Bank as a Servicer, the Trustee shall be entitled to reimbursement of such
costs and expenses from the Certificate Account. If the Master Servicer or
Trustee terminates an Other Servicing Agreement, the Trustee may enter into a
substitute Servicing Agreement with the Master Servicer or, at the Master
Servicer's nomination, with another mortgage loan service company acceptable to
the Trustee, the Master Servicer and each Rating Agency under which the Master
Servicer or such substitute servicer, as the case may be, shall assume, satisfy,
perform and carry out all liabilities, duties, responsibilities and obligations
that are to be, or otherwise were to have been, satisfied, performed and carried
out by such Servicer under such terminated Servicing Agreement. If the Trustee
terminates the Wells Fargo Bank Servicing Agreement, the Trustee shall enter
into a substitute Servicing Agreement with another mortgage loan service company
acceptable to the Trustee and each Rating Agency under which such substitute
servicer shall assume, satisfy, perform and carry out all liabilities, duties,
responsibilities and obligations that are to be, or otherwise were to have been,
satisfied, performed and carried out by Wells Fargo Bank, in its capacity as
Servicer, under such terminated Servicing Agreement. It is understood and
acknowledged by the parties hereto that there will be a period of transition not
to exceed ninety (90) days before the servicing functions can be transferred to
such substitute servicer. Until such time as the Trustee enters into a
substitute servicing agreement with respect to the Mortgage Loans previously
serviced by an Other Servicer and the transition period relating to the transfer
of such servicing expires, the Master Servicer shall assume, satisfy, perform
and carry out all obligations which otherwise were to have been satisfied,
performed and carried out by an Other Servicer under its terminated Servicing
Agreement. However, in no event shall the Master Servicer be deemed to have
assumed the obligations of a Servicer to advance payments of principal and
interest on a delinquent Mortgage Loan in excess of the Master Servicer's
independent Periodic Advance obligation under Section 3.03 of this Agreement. As
compensation for the Master Servicer of any servicing obligations fulfilled or
assumed by the Master Servicer, the Master Servicer shall be entitled to any
servicing compensation to which a Servicer would have been entitled if the
Servicing Agreement with such Servicer had not been terminated.

            Section 3.10 Application of Net Liquidation Proceeds.

            For all purposes under this agreement, Net Liquidation Proceeds
received from a Servicer shall be allocated first to accrued and unpaid interest
on the related Mortgage Loan and then to the unpaid principal balance thereof.

            Section 3.11 Assessment of Servicing Compliance; Registered Public
Accounting Firm Attestation Reports.

            (a) The Master Servicer, at its own expense, shall furnish to the
Depositor, and the Trustee, any Special Servicer (if applicable) and the
Custodian, at their own expense, shall furnish, or otherwise make available, and
shall cause any Servicing Function Participant engaged by any such party to
furnish, and the Master Servicer shall use reasonable effort to cause each
Servicer to furnish with respect to such Servicer and each Servicing Function
Participant engaged by such Servicer and identified to the Master Servicer, at
such party's expense, to the Master Servicer, not later than March 5 of each
year, or if such day is not a Business Day, the next Business Day (with a 10 day
cure period, but in no event later than March 15), commencing in March 2008, a
copy of a report, followed by a hard copy to the Master Servicer within 10
calendar days, signed by an authorized officer of the Master Servicer, the
Trustee, the Custodian, the Servicing Function Participant, the Special Servicer
(if applicable) or the applicable Servicer, as applicable, on assessment of
compliance with, at a minimum, the Relevant Servicing Criteria that contains:

            (i) a statement by such party of its responsibility for assessing
      compliance with the Servicing Criteria applicable to it;

            (ii) a statement that such party used the Servicing Criteria
      applicable to it to assess compliance with the Servicing Criteria;

            (iii) such party's assessment of compliance with the Servicing
      Criteria applicable to it as of and for the preceding fiscal year,
      including, if there had been any material instance of noncompliance with
      the Servicing Criteria applicable to it, identifying each such failure and
      the nature and status thereof; and

            (iv) a statement that a registered public accounting firm has issued
      an attestation report on such party's assessment of compliance with the
      Servicing Criteria applicable to it as of and for the preceding fiscal
      year.

            No later than 30 days following the end of each fiscal year, the
Master Servicer shall forward to the Depositor the name of each Servicing
Function Participant engaged by it and what Relevant Servicing Criteria will be
addressed in the report on assessment of compliance prepared by such Servicing
Function Participant. When the Master Servicer submits its assessments to the
Depositor, it will also at such time include the assessment (and attestation
pursuant to Section 3.11(b)) of each Servicing Function Participant engaged by
it.

            No later than 30 days following the end of each fiscal year, each of
the Trustee, any Special Servicer (if applicable) and the Custodian (so long as
the Custodian is not the Master Servicer) shall forward to the Master Servicer
the name of each Servicing Function Participant engaged by it and what Relevant
Servicing Criteria will be addressed in the report on assessment of compliance
prepared by such Servicing Function Participant. When the Trustee, any Special
Servicer (if applicable) and the Custodian (so long as the Custodian is not the
Master Servicer) submit their assessments to the Master Servicer, each such
party will also at such time include the assessment (and attestation pursuant to
Section 3.11(b)) of each Servicing Function Participant engaged by it.

            The Master Servicer shall confirm that the assessments address the
Relevant Servicing Criteria for each party as set forth on Exhibit R or in the
applicable Servicing Agreement or the applicable Special Servicing Agreement and
shall notify the Depositor of any exceptions and deliver the assessment of
compliance containing such exceptions. Promptly after receipt of each such
report on assessment of compliance, the Depositor shall review each such report
and, if applicable, consult with the Master Servicer, the Trustee, the
Custodian, any Special Servicer (if applicable) and any Servicing Function
Participant as to the nature of any material instance of noncompliance with the
Relevant Servicing Criteria by the Master Servicer, the Trustee, the Custodian,
any Servicer, any Special Servicer (if applicable), or any Servicing Function
Participant engaged by such parties.

            (b) The Master Servicer, at its own expense, shall cause a
registered public accounting firm which is a member of the Institute of
Certified Public Accountants to furnish to the Depositor, and each of the
Trustee, the Custodian and any Special Servicer (if applicable) at their own
expense, shall cause, and shall cause any Servicing Function Participant engaged
by any such party, at such party's expense, to cause, and the Master Servicer
shall use reasonable efforts to cause each Servicer, at such Servicer's expense,
with respect to such Servicer and each Servicing Function Participant engaged by
such Servicer and identified to the Master Servicer, to cause a registered
public accounting firm which is a member of the Institute of Certified Public
Accountants to furnish to the Master Servicer, not later than March 5 of each
year, or if such day is not a Business Day, the next Business Day (with a 10
calendar day cure period, but in no event later than March 15), commencing in
March 2008, an electronic report (with a hard copy to follow within 10 calendar
days) to the effect that (i) it has obtained a representation regarding certain
matters from the management of such party, which includes an assertion that such
party has complied with the Relevant Servicing Criteria, and (ii) on the basis
of an examination conducted by such firm in accordance with standards for
attestation engagements issued or adopted by the Public Company Accounting
Oversight Board, it is expressing an opinion as to whether such party's
assessment of compliance with the Relevant Servicing Criteria was fairly stated
in all material respects, or it cannot express an overall opinion regarding such
party's assessment of compliance with the Relevant Servicing Criteria. In the
event that an overall opinion cannot be expressed, such registered public
accounting firm shall state in such report why it was unable to express such an
opinion. Such report must be available for general use and not contain
restricted use language. If requested by the Master Servicer or the Depositor,
such report shall contain or be accompanied by a consent of such accounting firm
to inclusion or incorporation of such report in the Depositor's Registration
Statement on Form S-3 relating to the Certificates and the Trust's Form 10-K.

            Promptly after receipt of such report from the Master Servicer, the
Depositor shall review the report and, if applicable, consult with the Master
Servicer if any such report (i) states that the party's assessment of compliance
was not fairly stated in a material respect or (ii) is unable to state an
overall opinion.

            Promptly after receipt of such report from the Trustee, the
Custodian, the applicable Servicer, the Special Servicer (if applicable), or any
Servicing Function Participant engaged by such parties, the Master Servicer
shall review the report and shall promptly notify the Depositor if any such
report (i) states that the party's assessment of compliance was not fairly
stated in a material respect or (ii) is unable to state an overall opinion and
the Depositor shall promptly review each such report and the Depositor and the
Master Servicer shall consult with the parties to which such report relates.

            The Master Servicer shall make available any report from the Master
Servicer, the Trustee, the Custodian, the applicable Servicer, the Special
Servicer (if applicable), or any Servicing Function Participant furnished
pursuant to Section 3.05 and this Section 3.11, as well as any documents
incorporated by reference into the Prospectus (to the extent such documents are
either in its possession or have been filed with the Commission), to any
Certificateholder requesting such information.

            Section 3.12 Exchange Act Reports.

            (a) Within 15 days after each Distribution Date, the Master Servicer
shall prepare, an authorized officer of the Master Servicer shall sign, and the
Master Servicer shall file with the Commission, on behalf of the Trust, any Form
10-D required by the Exchange Act, in form and substance as required by the
Exchange Act. The Master Servicer shall file each Form 10-D with a copy of the
related Distribution Date Statement attached thereto. Any disclosure in addition
to the Distribution Date Statement that is required to be included on Form 10-D
("Additional Form 10-D Disclosure") shall be reported by the parties set forth
on Exhibit S and directed and approved by the Depositor, and the Master Servicer
will have no duty or liability for any failure hereunder to determine or prepare
any Additional Form 10-D Disclosure (other than with respect to itself) absent
such reporting, direction and approval. If a Form 10-D cannot be filed on time
or if a previously filed Form 10-D needs to be amended, the Master Servicer will
follow the procedures set forth in Section 3.12(d). Promptly (but no later than
1 Business Day) after filing with the Commission, the Master Servicer will make
available on its internet website a final executed copy of each Form 10-D.

            For so long as the Trust is subject to the Exchange Act reporting
requirements, within five (5) calendar days (or, solely in the case of Item 7 of
Exhibit S, the greater of five (5) calendar days or three (3) Business Days)
after the related Distribution Date, the parties identified on Exhibit S shall
(i) provide to the Master Servicer and the Depositor, to the extent known by a
Responsible Officer, in EDGAR-compatible format, or in such other format as
otherwise agreed upon by the Master Servicer and such party, the form and
substance of any Additional Form 10-D Disclosure, if applicable and (ii) include
with such Additional Form 10-D Disclosure, an Additional Disclosure Notification
in the form attached hereto as Exhibit V, and the Depositor will approve, as to
form and substance, or disapprove, as the case may be, the inclusion of the
Additional Form 10-D Disclosure on Form 10-D. The Master Servicer has no duty
under this Agreement to monitor or enforce the performance by the parties listed
on Exhibit S of their duties under this paragraph or proactively solicit or
procure from such parties any Additional Form 10-D Disclosure; except that the
Master Servicer shall enforce the obligations of the Servicers under the
Servicing Agreements. After preparing the Form 10-D, if the Form 10-D contains
any Additional Form 10-D Disclosure, the Master Servicer shall forward
electronically a draft copy of the Form 10-D to the Depositor for review. Each
party to this Agreement acknowledges that the performance by the Master Servicer
of its duties under this Section 3.12(a) relating to the timely preparation and
filing of Form 10-D is contingent upon such parties strictly observing all
applicable deadlines in the performance of their duties under this Section
3.12(a). The Master Servicer shall have no liability for any loss, expense,
damage, claim arising out of or with respect to any failure to properly prepare
and/or timely file such Form 10-D, where such failure results from the Master
Servicer's inability or failure to receive, on a timely basis, any information
from any other party hereto, any Servicer, the Custodian or any Special Servicer
(if applicable) needed to prepare, arrange for execution or file such Form 10-D,
not resulting from its own negligence, bad faith or willful misconduct. The
Depositor will be responsible for any reasonable fees assessed and expenses
incurred by the Master Servicer in connection with including any Additional Form
10-D Disclosure on Form 10-D pursuant to this paragraph.

            (b) Within 90 days after the end of each fiscal year of the Trust or
such earlier date as may be required by the Exchange Act (it being understood
that the fiscal year for the Trust ends on December 31st of each year),
commencing in March 2008, the Master Servicer shall prepare, a senior officer of
the Master Servicer in charge of the master servicing function shall sign, and
the Master Servicer shall file with the Commission, on behalf of the Trust, a
Form 10-K, in form and substance as required by the Exchange Act. Each such Form
10-K shall include the following items, in each case to the extent they have
been delivered to the Master Servicer within the applicable timeframes set forth
in this Agreement, the related Servicing Agreements, the Custodial Agreement or,
if applicable, the Special Servicing Agreement:

            (i) an annual compliance statement for the Master Servicer, any
      Additional Master Servicer and each Servicer, as described under Section
      3.05;

            (ii) (A) the annual reports on assessment of compliance with
      servicing criteria for the Master Servicer, the Trustee, each Servicer,
      the Custodian, any Special Servicer (if applicable), and each Servicing
      Function Participant, as described under Section 3.11(a), and (B) if any
      party's report on assessment of compliance with Servicing Criteria
      described under Section 3.11(a) identifies any material instance of
      noncompliance, disclosure identifying such instance of noncompliance, or
      if any party's report on assessment of compliance with servicing criteria
      described under Section 3.11(a) is not included as an exhibit to such Form
      10-K, disclosure that such report is not included and an explanation of
      why such report is not included;

            (iii) (A) the registered public accounting firm attestation report
      for each of the Master Servicer, the Trustee, each Servicer, the
      Custodian, any Special Servicer (if applicable), and each Servicing
      Function Participant, as described under Section 3.11(b), and (B) if any
      registered public accounting firm attestation report described under
      Section 3.11(b) identifies any material instance of noncompliance,
      disclosure identifying such instance of noncompliance, or if any such
      registered public accounting firm attestation report is not included as an
      exhibit to such Form 10-K, disclosure that such report is not included and
      an explanation of why such report is not included; and

            (iv) a certification, signed by a senior officer of the Master
      Servicer in charge of the master servicing function, in the form attached
      hereto as Exhibit P or in such other form as may be required by Rules
      13a-14 and 15d-14 under the Exchange Act, as applicable, and any
      directives or interpretations thereof by the Commission (the
      "Sarbanes-Oxley Certification").

            Any disclosure or information in addition to (i) through (iv) above
that is required to be included on Form 10-K ("Additional Form 10-K Disclosure")
shall, pursuant to the paragraph immediately below, be reported by the parties
set forth on Exhibit T and directed and approved by the Depositor, and the
Master Servicer will have no duty or liability for any failure hereunder to
determine or prepare any Additional Form 10-K Disclosure (other than with
respect to itself) absent such reporting, direction and approval. If a Form 10-K
cannot be filed on time or if a previously filed Form 10-K needs to be amended,
the Master Servicer will follow the procedures set forth in Section 3.12(d).
Promptly (but no later than 1 Business Day) after filing with the Commission,
the Master Servicer will make available on its internet website a final executed
copy of each Form 10-K.

            No later than March 5 (with a 10 calendar day cure period, but in no
event later than March 15) of each year that the Trust is subject to the
Exchange Act reporting requirements, commencing in March 2008, (i) the parties
identified on Exhibit T shall provide to the Master Servicer and the Depositor,
to the extent known by a Responsible Officer, in EDGAR-compatible format, or in
such other format as otherwise agreed upon by the Master Servicer and such
party, the form and substance of any Additional Form 10-K Disclosure, if
applicable, and (ii) the parties identified on Exhibit T shall include with such
Additional Form 10-K Disclosure, an Additional Disclosure Notification in the
form attached hereto as Exhibit V, and the Depositor will approve, as to form
and substance, or disapprove, as the case may be, the inclusion of the
Additional Form 10-K Disclosure on Form 10-K. The Master Servicer has no duty
under this Agreement to monitor or enforce the performance by the parties listed
on Exhibit T of their duties under this paragraph or proactively solicit or
procure from such parties any Additional Form 10-K Disclosure information;
except that the Master Servicer shall enforce the obligations of the Servicers
under the Servicing Agreements. The Depositor will be responsible for any
reasonable fees and expenses assessed or incurred by the Master Servicer in
connection with including any Additional Form 10-K Disclosure on Form 10-K
pursuant to this paragraph.

            After preparing the Form 10-K, if the Form 10-K contains any
Additional Form 10-K Disclosure, the Master Servicer shall forward
electronically a draft copy of the Form 10-K to the Depositor for review. Each
party to this Agreement acknowledges that the performance by the Master Servicer
of its duties under this Section 3.12(b) relating to the timely preparation and
filing of Form 10-K is contingent upon such parties strictly observing all
applicable timeframes in the performance of their duties under Sections 3.05,
3.11 or this Section 3.12(b). The Master Servicer shall have no liability for
any loss, expense, damage, claim arising out of or with respect to any failure
to properly prepare and/or timely file such Form 10-K, where such failure
results from the Master Servicer's inability or failure to obtain or receive, on
a timely basis, any information from any other party hereto, any Servicer, any
Special Servicer (if applicable) or the Custodian needed to prepare, arrange for
execution or file such Form 10-K, not resulting from its own negligence, bad
faith or willful misconduct.

            (c) Within four (4) Business Days after the occurrence of an event
requiring disclosure on Form 8-K (each such event, a "Reportable Event"), and if
directed by the Depositor, the Master Servicer shall prepare, an authorized
officer of the Master Servicer shall sign, and the Master Servicer shall file
with the Commission, on behalf of the Trust, any Form 8-K, as required by the
Exchange Act, provided that the Depositor shall prepare and file the initial
Form 8-K in connection with the issuance of the Certificates. Any disclosure or
information related to a Reportable Event or that is otherwise required to be
included on Form 8-K ("Form 8-K Disclosure Information") shall, pursuant to the
paragraph immediately below, be reported by the parties set forth on Exhibit U
and directed and approved by the Depositor, and the Master Servicer will have no
duty or liability for any failure hereunder to determine or prepare any Form 8-K
Disclosure Information (other than with respect to itself) absent such
reporting, direction and approval. If a Form 8-K cannot be filed on time or if a
previously filed Form 8-K needs to be amended, the Master Servicer will follow
the procedures set forth in Section 3.12(d). Promptly (but no later than 1
Business Day) after filing with the Commission, the Master Servicer will, make
available on its internet website a final executed copy of each Form 8-K.

            For so long as the Trust is subject to the Exchange Act reporting
requirements, no later than the end of business on the second Business Day after
the occurrence of a Reportable Event (i) the parties identified on Exhibit U
shall provide to the Master Servicer and the Depositor, to the extent known by a
Responsible Officer, in EDGAR-compatible form, or in such other form as
otherwise agreed upon by the Master Servicer and such party, the form and
substance of any Form 8-K Disclosure Information, if applicable, and (ii) the
parties identified on Exhibit U shall include with such Additional Form 8-K
Disclosure, an Additional Disclosure Notification in the form attached hereto as
Exhibit V and the Depositor will approve, as to form and substance, or
disapprove, as the case may be, the inclusion of the Form 8-K Disclosure
Information on Form 8-K. The Master Servicer has no duty under this Agreement to
monitor or enforce the performance by the parties listed on Exhibit U of their
duties under this paragraph or proactively solicit or procure from such parties
any Form 8-K Disclosure Information; except that the Master Servicer shall
enforce the obligations of the Servicers under the Servicing Agreements. The
Depositor will be responsible for any reasonable fees and expenses assessed or
incurred by the Master Servicer in connection with including any Form 8-K
Disclosure Information on Form 8-K pursuant to this paragraph.

            After preparing the Form 8-K, the Master Servicer shall forward
electronically a draft copy of the Form 8-K to the Depositor for review. Each
party to this Agreement acknowledges that the performance by the Master Servicer
of its duties under this Section 3.12(c) relating to the timely preparation and
filing of Form 8-K is contingent upon such party strictly observing all
applicable timeframes in the performance of its duties under this Section
3.12(c). The Master Servicer shall have no liability for any loss, expense,
damage, claim arising out of or with respect to any failure to properly prepare
and/or timely file such Form 8-K, where such failure results from the Master
Servicer's inability or failure to obtain or receive, on a timely basis, any
information from any other party hereto, any Servicer, the Custodian or any
Special Servicer (if applicable) needed to prepare, arrange for execution or
file such Form 8-K, not resulting from its own negligence, bad faith or willful
misconduct.

            (d) In the event that the Master Servicer is unable to timely file
with the Commission all or any required portion of any Form 8-K, 10-D or 10-K
required to be filed by this Agreement because required disclosure information
was either not delivered to it or delivered to it after the delivery deadlines
set forth in this Agreement or for any other reason, the Master Servicer will
promptly notify the Depositor and, in the case of Form 10-D or 10-K, the Master
Servicer will prepare, sign and file a Form 12b-25 pursuant to Rule 12b-25 of
the Exchange Act not later than the Business Day following the due date of the
applicable report. Within five days following the due date of any Form 10-D as
to which it has filed a Form 12b-25, the Master Servicer shall prepare, sign and
file the related Form 10-D. Within 15 days following the due date of any Form
10-K as to which it has filed a Form 12b-25, the Master Servicer shall prepare,
sign and file the related Form 10-K. In the case of Form 8-K, the Master
Servicer will, upon receipt of all required Form 8-K Disclosure Information and
at the direction of the Depositor, include such disclosure information on the
next Form 10-D. In the event that any previously filed Form 8-K, 10-D or 10-K
needs to be amended, the Master Servicer will notify the Depositor and each
party whose cooperation is required in connection with the preparation of such
amendment; provided however that such notice shall not be required in connection
with an amendment to Form 10-D due to a revision made to any Distribution Date
Statement. The parties to this Agreement acknowledge that the performance by the
Master Servicer of its duties under this Section 3.12(d) related to the timely
preparation and filing of a Form 12b-25 or any amendment to Form 8-K, 10-D or
10-K is contingent upon each such party performing its duties under this
Section. The Master Servicer shall have no liability for any loss, expense,
damage, claim arising out of or with respect to any failure to properly prepare
and/or timely file any such Form 12b-25 or any amendments to Forms 8-K, 10-D or
10-K, where such failure results from the Master Servicer's inability or failure
to obtain or receive, on a timely basis, any information from any other party
hereto, any Servicer, the Custodian or any Special Servicer (if applicable)
needed to prepare, arrange for execution or file such Form 12b-25 or any
amendments to Forms 8-K, 10-D or 10-K, not resulting from its own negligence,
bad faith or willful misconduct.

            (e) On or prior to January 30 of the first year in which the Master
Servicer is able to do so under applicable law, the Master Servicer shall
prepare, an authorized officer of the Master Servicer shall sign, and the Master
Servicer shall file with the Commission, on behalf of the Trust, a Form 15
relating to the automatic suspension of reporting in respect of the Trust under
the Exchange Act. At the beginning of any year after the filing of a Form 15, if
the number of Certificateholders of record exceeds the number set forth in
Section 15(d) of the Exchange Act or the regulations promulgated pursuant
thereto which would cause the Trust to again become subject to the reporting
requirements of the Exchange Act, the Master Servicer shall recommence preparing
and filing reports on Form 10-D, 10-K and 8-K as required pursuant to this
Section.

            (f) To the extent the Master Servicer is obligated to give any
notice to the Depositor pursuant to this Section 3.12, such notice may,
notwithstanding the provisions of Section 10.05 in this Agreement, be delivered
via facsimile to 301-816-8152 or via electronic mail to
Structuredfinance-frederick@wellsfargo.com.

<PAGE>

                                   ARTICLE IV

                    DISTRIBUTIONS IN RESPECT OF CERTIFICATES;
                         PAYMENTS TO CERTIFICATEHOLDERS;
                             STATEMENTS AND REPORTS

            Section 4.01 Distributions.

            (a) On each Distribution Date, the Pool Distribution Amount will be
applied in the following amounts, to the extent the Pool Distribution Amount is
sufficient therefor, in the manner and in the order of priority as follows:

            first, to the Classes of Class A Certificates, pro rata, based upon
their respective Interest Accrual Amounts, in an aggregate amount up to the
Class A Interest Accrual Amount with respect to such Distribution Date; provided
that prior to the applicable Accretion Termination Date, an amount equal to the
amount that would otherwise be distributable in respect of interest to a Class
of Accrual Certificates pursuant to this provision will instead be distributed
in reduction of the Principal Balances of certain Classes of Class A
Certificates, in accordance with Section 4.01(b);

            second, to the Classes of Class A Certificates, pro rata, based upon
their respective Class A Unpaid Interest Shortfalls in an aggregate amount up to
the Aggregate Class A Unpaid Interest Shortfall; provided that prior to the
applicable Accretion Termination Date, an amount equal to the amount that would
otherwise be distributable in respect of unpaid interest shortfalls to a Class
of Accrual Certificates pursuant to this provision will instead be distributed
in reduction of the Principal Balances of certain Classes of Class A
Certificates, in accordance with Section 4.01(b);

            third, concurrently, to the Class A Certificates (other than the
Class A-PO Certificates) and the Class A-PO Certificates, pro rata, based on
their respective Class A Non-PO Optimal Principal Amount and Class A-PO Optimal
Principal Amount, (1) to the Classes of Class A Certificates (other than the
Class A-PO Certificates), in an aggregate amount up to the Class A Non-PO
Optimal Principal Amount, such distribution to be allocated among such Classes
in accordance with Section 4.01(b) or Section 4.01(c), as applicable, and (2) to
the Class A-PO Certificates in an amount up to the Class A-PO Optimal Principal
Amount;

            fourth, to the Class A-PO Certificates in an amount up to the Class
A-PO Deferred Amount from amounts otherwise distributable (without regard to
this Paragraph fourth) first to the Class B-6 Certificates pursuant to Paragraph
twenty-second, below, second to the Class B-5 Certificates pursuant to Paragraph
nineteenth, below, third to the Class B-4 Certificates pursuant to Paragraph
sixteenth, below, fourth to the Class B-3 Certificates pursuant to Paragraph
thirteenth, below, fifth to the Class B-2 Certificates pursuant to Paragraph
tenth below, and sixth to the Class B-1 Certificates pursuant to Paragraph
seventh below;

            fifth, to the Class B-1 Certificates in an amount up to the Interest
Accrual Amount for the Class B-1 Certificates with respect to such Distribution
Date;

            sixth, to the Class B-1 Certificates in an amount up to the Class
B-1 Unpaid Interest Shortfall;

            seventh, to the Class B-1 Certificates in an amount up to the Class
B-1 Optimal Principal Amount; provided, however, that the amount distributable
to the Class B-1 Certificates pursuant to this Paragraph seventh will be reduced
by the amount, if any, that would have been distributable to the Class B-1
Certificates hereunder used to pay the Class A-PO Deferred Amount as provided in
Paragraph fourth above;

            eighth, to the Class B-2 Certificates in an amount up to the
Interest Accrual Amount for the Class B-2 Certificates with respect to such
Distribution Date;

            ninth, to the Class B-2 Certificates in an amount up to the Class
B-2 Unpaid Interest Shortfall;

            tenth, to the Class B-2 Certificates in an amount up to the Class
B-2 Optimal Principal Amount; provided, however, that the amount distributable
to the Class B-2 Certificates pursuant to this Paragraph tenth will be reduced
by the amount, if any, that would have been distributable to the Class B-2
Certificates hereunder used to pay the Class A-PO Deferred Amount as provided in
Paragraph fourth above;

            eleventh, to the Class B-3 Certificates in an amount up to the
Interest Accrual Amount for the Class B-3 Certificates with respect to such
Distribution Date;

            twelfth, to the Class B-3 Certificates in an amount up to the Class
B-3 Unpaid Interest Shortfall;

            thirteenth, to the Class B-3 Certificates in an amount up to the
Class B-3 Optimal Principal Amount; provided, however, that the amount
distributable to the Class B-3 Certificates pursuant to this Paragraph
thirteenth will be reduced by the amount, if any, that would have been
distributable to the Class B-3 Certificates hereunder used to pay the Class A-PO
Deferred Amount as provided in Paragraph fourth above;

            fourteenth, to the Class B-4 Certificates in an amount up to the
Interest Accrual Amount for the Class B-4 Certificates with respect to such
Distribution Date;

            fifteenth, to the Class B-4 Certificates in an amount up to the
Class B-4 Unpaid Interest Shortfall;

            sixteenth, to the Class B-4 Certificates in an amount up to the
Class B-4 Optimal Principal Amount; provided, however, that the amount
distributable to the Class B-4 Certificates pursuant to this Paragraph sixteenth
will be reduced by the amount, if any, that would have been distributable to the
Class B-4 Certificates hereunder used to pay the Class A-PO Deferred Amount as
provided in Paragraph fourth above;

            seventeenth, to the Class B-5 Certificates in an amount up to the
Interest Accrual Amount for the Class B-5 Certificates with respect to such
Distribution Date;

            eighteenth, to the Class B-5 Certificates in an amount up to the
Class B-5 Unpaid Interest Shortfall;

            nineteenth, to the Class B-5 Certificates in an amount up to the
Class B-5 Optimal Principal Amount; provided, however, that the amount
distributable to the Class B-5 Certificates pursuant to this Paragraph
nineteenth will be reduced by the amount, if any, that would have been
distributable to the Class B-5 Certificates hereunder used to pay the Class A-PO
Deferred Amount as provided in Paragraph fourth above;

            twentieth, to the Class B-6 Certificates in an amount up to the
Interest Accrual Amount for the Class B-6 Certificates with respect to such
Distribution Date;

            twenty-first, to the Class B-6 Certificates in an amount up to the
Class B-6 Unpaid Interest Shortfall;

            twenty-second, to the Class B-6 Certificates in an amount up to the
Class B-6 Optimal Principal Amount; provided, however, that the amount
distributable to the Class B-6 Certificates pursuant to this Paragraph
twenty-second will be reduced by the amount, if any, that would have been
distributable to the Class B-6 Certificates hereunder used to pay the Class A-PO
Deferred Amount as provided in Paragraph fourth above; and

            twenty-third, to the Holder of the Class A-R Certificate (i) in
respect of the Class A-R Interest, any amounts remaining in the Upper-Tier
Certificate Account and (ii) in respect of the Class A-LR Interest, any amounts
remaining in the Payment Account.

            Notwithstanding the foregoing, after the Principal Balance or
Notional Amount of any Class has been reduced to zero, such Class will be
entitled to no further distributions of principal or interest (including,
without limitation, any Unpaid Interest Shortfalls).

            With respect to any Distribution Date, the amount of the Principal
Adjustment, if any, attributable to any Class of Class B Certificates will be
allocated to the Classes of Class A Certificates (other than the Class A-PO
Certificates) and any Class of Class B Certificates with a lower numerical
designation pro rata based on their outstanding Principal Balances.

            On each Distribution Date, any Reimbursement Amount shall be
distributed sequentially to the Classes of Certificates then outstanding which
bore the loss to which such Reimbursement Amount relates beginning with the most
senior of such Class of Certificates, up to, with respect to each Class, the
amount of loss borne by such Class. Any Reimbursement Amount remaining after the
application described in the preceding sentence shall be included in the Pool
Distribution Amount.

            Distributions on the Uncertificated Lower-Tier Interests. Each
Uncertificated Lower-Tier Interest shall receive distributions in respect of
principal in an amount equal to the amount of principal distributed to its
respective Corresponding Upper-Tier Class or Classes as provided herein. Each
Uncertificated Lower-Tier Interest (other than the Class A-LPO Interest) shall
receive distributions in respect of interest in an amount equal to the Interest
Accrual Amounts and Unpaid Interest Shortfalls, as the case may be, in respect
of its Corresponding Upper-Tier Class or Classes, in each case to the extent
actually distributed thereon. Such amounts distributed to the Uncertificated
Lower-Tier Interests in respect of principal and interest with respect to any
Distribution Date are referred to herein collectively as the "Lower-Tier
Distribution Amount."

            As of any date, the principal balance of each Uncertificated
Lower-Tier Interest equals the Principal Balances of the respective
Corresponding Upper-Tier Class or Classes. The initial principal balance of each
Uncertificated Lower-Tier Interest equals the Original Principal Balances of the
respective Corresponding Upper-Tier Class or Classes.

            The pass-through rate with respect to the Class A-L1 Interest, Class
A-L5 Interest, Class A-L7 Interest, Class A-L16 Interest, Class A-LUR Interest,
Class B-L1 Interest, Class B-L2 Interest, Class B-L3 Interest, Class B-L4
Interest, Class B-L5 Interest and Class B-L6 Interest shall be 6.000% per annum.
The Class A-LPO Interest is a principal-only interest and is not entitled to
distributions of interest. Any Non-Supported Interest Shortfalls will be
allocated to each Uncertificated Lower-Tier Interest in the same relative
proportions as interest is allocated to such Uncertificated Lower-Tier Interest.

            (b) The Class A-19 Certificates are Interest Only Certificates and
are not entitled to distributions in respect of principal.

            I. On each Distribution Date occurring prior to the Accretion
      Termination Date for the Class A-10 Certificates, the applicable Accrual
      Distribution Amount will be distributed, sequentially, as follows:

            first, to the Class A-5 Certificates, up to the Reduction Amount for
            such Distribution Date; and

            second, sequentially to the Class A-6, Class A-5 and Class A-10
            Certificates.

            II. On each Distribution Date occurring prior to the Accretion
      Termination Date for the Class A-6 Certificates, the applicable Accrual
      Distribution Amount will be distributed, sequentially, as follows:

            first, to the Class A-5 Certificates, up to the Reduction Amount for
            such Distribution Date; and

            second, to the Class A-6 Certificates.

            III. On each Distribution Date occurring prior to the Subordination
Depletion Date, the Class A Non-PO Principal Distribution Amount will be
allocated among and distributed in reduction of the Principal Balances of the
Class A Non-PO Certificates, concurrently, as follows:

                  (a) 9.1854939955%, to the Class A-4 Certificates;

                  (b) 90.8145060045%, sequentially, as follows:

                        (i) to the Class A-R Certificate;

                        (ii) concurrently, to the Class A-2, Class A-3 and Class
                        A-15 Certificates, pro rata, up to the Priority Amount
                        for such Distribution Date;

                        (iii) concurrently, as follows:

                              (A) 44.8261171053%, sequentially, to the Class A-1
                              and Class A-8 Certificates;

                              (B) 29.6949509088%, sequentially, as follows:

                                    (1) concurrently, to the Class A-7, Class
                                    A-11, Class A-12 and Class A-13
                                    Certificates, pro rata; and

                                    (2) to the Class A-14 Certificates; and

                              (C) 25.4789319859%, sequentially, as follows:

                                    (1) sequentially, up to the PAC I Principal
                                    Amount for such Distribution Date, as
                                    follows:

                                          (aa) concurrently, as follows:

                                                (x) 50.00%, to the Class A-16
                                                Certificates; and

                                                (y) 50.00%, sequentially, to
                                                the Class A-20 and Class A-21
                                                Certificates; and

                                          (bb) sequentially, to the Class
                                          A-17 and Class A-18 Certificates;

                                    (2) to the Class A-9 Certificates, up to the
                                    PAC II Principal Amount for such
                                    Distribution Date;

                                    (3) to the Class A-5 Certificates, up to the
                                    Reduction Amount for such Distribution Date;

                                    (4) sequentially, to the Class A-6, Class
                                    A-5, Class A-10 and Class A-9 Certificates;

                                    (5) concurrently, as follows:

                                          (aa) 50.00%, to the Class A-16
                                          Certificates; and

                                          (bb) 50.00%, sequentially, to the
                                          Class A-20 and Class A-21
                                          Certificates; and

                                    (6) sequentially, to the Class A-17 and
                                    Class A-18 Certificates; and

                        (iv) concurrently, to the Class A-2, Class A-3 and Class
                        A-15 Certificates, pro rata.

            (c) Notwithstanding the foregoing, on each Distribution Date
occurring on or subsequent to the Subordination Depletion Date, the Class A
Non-PO Principal Distribution Amount shall be distributed among the Classes of
Class A Non-PO Certificates, pro rata, in accordance with their outstanding
Principal Balances without regard to either the proportions or the priorities
set forth in Section 4.01(b).

            As used above, the "PAC I Principal Amount" for any Distribution
Date means the amount, if any, that would reduce the sum of the Principal
Balances of the PAC I Certificates to the percentage of the initial aggregate
Principal Balance of the PAC I Certificates shown in the related table appearing
in Schedule II with respect to such Distribution Date.

            As used above, the "PAC II Principal Amount" for any Distribution
Date means the amount, if any, that would reduce the Principal Balance of the
PAC II Certificates to the percentage of the initial Principal Balance of the
PAC II Certificates shown in the related table appearing in Schedule II with
respect to such Distribution Date.

            As used above, the "Reduction Amount" for any Distribution Date
means the amount, if any, that would reduce the Principal Balance of the
Scheduled Certificates to the percentage of the initial Principal Balance of the
Scheduled Certificates shown in the related table appearing in Schedule II with
respect to such Distribution Date.

            The tables in Schedule II set forth for each Distribution Date the
planned Principal Balances for the PAC I Group and PAC II Certificates and the
scheduled Principal Balances for the Scheduled Certificates expressed as a
percentage of the initial aggregate Principal Balance of the PAC I Group and the
initial Principal Balance of the PAC II and Scheduled Certificates,
respectively.

            (d) (i) For purposes of determining whether the Classes of Class B
Certificates are eligible to receive distributions of principal with respect to
any Distribution Date, the following tests shall apply:

            (A) if the Current Class B-1 Fractional Interest is less than the
      Original Class B-1 Fractional Interest and the Class B-1 Principal Balance
      is greater than zero, the Class B-2, Class B-3, Class B-4, Class B-5 and
      Class B-6 Certificates shall not be eligible to receive distributions of
      principal; or

            (B) if the Current Class B-2 Fractional Interest is less than the
      Original Class B-2 Fractional Interest and the Class B-2 Principal Balance
      is greater than zero, the Class B-3, Class B-4, Class B-5 and Class B-6
      Certificates shall not be eligible to receive distributions of principal;
      or

            (C) if the Current Class B-3 Fractional Interest is less than the
      Original Class B-3 Fractional Interest and the Class B-3 Principal Balance
      is greater than zero, the Class B-4, Class B-5 and Class B-6 Certificates
      shall not be eligible to receive distributions of principal; or

            (D) if the Current Class B-4 Fractional Interest is less than the
      Original Class B-4 Fractional Interest and the Class B-4 Principal Balance
      is greater than zero, the Class B-5 and Class B-6 Certificates shall not
      be eligible to receive distributions of principal; or

            (E) if the Current Class B-5 Fractional Interest is less than the
      Original Class B-5 Fractional Interest and the Class B-5 Principal Balance
      is greater than zero, the Class B-6 Certificates shall not be eligible to
      receive distributions of principal.

            (ii) Notwithstanding the foregoing, if on any Distribution Date the
      aggregate distributions to Holders of the Classes of Class B Certificates
      entitled to receive distributions of principal would reduce the Principal
      Balances of the Classes of Class B Certificates entitled to receive
      distributions of principal below zero, first the Class B Prepayment
      Percentage of any affected Class of Class B Certificates for such
      Distribution Date beginning with the affected Class with the lowest
      numerical Class designation and then, if necessary, the Class B Percentage
      of such Class of the Class B Certificates for such Distribution Date shall
      be reduced to the respective percentages necessary to bring the Principal
      Balance of such Class of Class B Certificates to zero. The Class B
      Prepayment Percentages and the Class B Percentages of the remaining
      Classes of Class B Certificates will be recomputed substituting for the
      Subordinated Prepayment Percentage and Subordinated Percentage in such
      computations the difference between (A) the Subordinated Prepayment
      Percentage or Subordinated Percentage, as the case may be, and (B) the
      percentages determined in accordance with the preceding sentence necessary
      to bring the Principal Balances of the affected Classes of Class B
      Certificates to zero; provided, however, that if the Principal Balances of
      all the Classes of Class B Certificates eligible to receive distributions
      of principal shall be reduced to zero on such Distribution Date, the Class
      B Prepayment Percentage and Class B Percentage of the Class of Class B
      Certificates with the lowest numerical Class designation which would
      otherwise be ineligible to receive distributions of principal in
      accordance with this Section shall equal the remainder of the Subordinated
      Prepayment Percentage for such Distribution Date minus the sum of the
      Class B Prepayment Percentages of the Classes of Class B Certificates
      having lower numerical Class designations, if any, and the remainder of
      the Subordinated Percentage for such Distribution Date minus the sum of
      the Class B Percentages of the Classes of Class B Certificates having
      lower numerical Class designations, if any, respectively. Any entitlement
      of any Class of Class B Certificates to principal payments solely pursuant
      to this clause (ii) shall not cause such Class to be regarded as being
      eligible to receive principal distributions for the purpose of applying
      the definition of its Class B Percentage or Class B Prepayment Percentage.

            (e) The Master Servicer shall establish and maintain the Upper-Tier
Certificate Account, which shall be a separate trust account and an Eligible
Account (provided that such account may be deemed a sub-account of the Payment
Account so long as the Master Servicer is the Paying Agent). On each
Distribution Date other than the Final Distribution Date (if such Final
Distribution Date is in connection with a purchase of the assets of the Trust
Estate by the Depositor), the Paying Agent shall, on behalf of the Master
Servicer, from funds available on deposit in the Payment Account, be deemed to
deposit, in immediately available funds, by wire transfer or otherwise, into the
Upper-Tier Certificate Account the Lower-Tier Distribution Amount. The Master
Servicer may clear and terminate the Upper-Tier Certificate Account pursuant to
Section 9.01.

            (f) On each Distribution Date other than the Final Distribution Date
(if such Final Distribution Date is in connection with a purchase of the assets
of the Trust Estate by the Depositor), the Paying Agent shall, from funds
remitted to it by the Master Servicer, distribute to each Certificateholder of
record on the preceding Record Date (other than as provided in Section 9.01
respecting the final distribution to Certificateholders or in the last paragraph
of this Section 4.01(f) respecting the final distribution in respect of any
Class) either in immediately available funds by wire transfer to the account of
such Certificateholder at a bank or other entity having appropriate facilities
therefor, if such Certificateholder has so notified the Paying Agent at least
seven Business Days prior to the Distribution Date or if such Holder has not so
notified the Paying Agent, by check mailed to such Holder at the address of such
Holder appearing in the Certificate Register, such Holder's share of the Class A
Distribution Amount with respect to each Class of Class A Certificates and the
Class B Distribution Amount with respect to each Class of Class B Certificates.

            In the event that, on any Distribution Date prior to the Final
Distribution Date, the Principal Balance of any Class of Class A Certificates
(other than the Residual Certificate) or the Principal Balance of any Class of
Class B Certificates would be reduced to zero, or in the case of a Class of
Interest Only Certificates, the related Notional Amount, would be reduced to
zero, the Master Servicer shall, as soon as practicable after the Determination
Date relating to such Distribution Date, send notice to the Paying Agent. The
Paying Agent shall then send a notice to each Certificateholder of such Class
with a copy to the Certificate Registrar, specifying that the final distribution
with respect to such Class will be made on such Distribution Date only upon the
presentation and surrender of such Certificateholder's Certificates at the
office or agency of the Certificate Registrar therein specified; provided,
however, that the failure to give such notice will not entitle a
Certificateholder to any interest beyond the interest payable with respect to
such Distribution Date in accordance with Section 4.01(a).

            (g) The Paying Agent shall withhold or cause to be withheld such
amounts as may be required by the Code (giving full effect to any exemptions
from withholding and related certifications required to be furnished by
Certificateholders and any reductions to withholding by virtue of any bilateral
tax treaties and any applicable certification required to be furnished by
Certificateholders with respect thereto) from distributions to be made to
Persons other than U.S. Persons ("Non-U.S. Persons"). Amounts withheld pursuant
to this Section 4.01(g) shall be treated as having been distributed to the
related Certificateholder for all purposes of this Agreement. For the purposes
of this paragraph, a "U.S. Person" is a citizen or resident of the United
States, a corporation or partnership (unless, in the case of a partnership,
Treasury regulations are adopted that provide otherwise) created or organized in
or under the laws of the United States, any state thereof or the District of
Columbia, including an entity treated as a corporation or partnership for
federal income tax purposes, an estate whose income is subject to United States
federal income tax regardless of its source, or a trust if a court within the
United States is able to exercise primary supervision over the administration of
such trust, and one or more such U.S. Persons have the authority to control all
substantial decisions of such trust (or, to the extent provided in applicable
Treasury regulations, certain trusts in existence on August 20, 1996 which are
eligible to elect to be treated as U.S. Persons).

            Section 4.02 Allocation of Realized Losses.

            (a) With respect to any Distribution Date, the principal portion of
any Realized Loss (other than Debt Service Reductions) will be allocated as
follows:

            first, concurrently, to the Class A-PO Certificates and Class B-6
Certificates, pro rata, based on the applicable PO Fraction and the applicable
Non-PO Fraction of such Mortgage Loans, respectively, until the Class B-6
Principal Balance has been reduced to zero;

            second, concurrently, to the Class A-PO Certificates and Class B-5
Certificates, pro rata, based on the applicable PO Fraction and the applicable
Non-PO Fraction of such Mortgage Loans, respectively, until the Class B-5
Principal Balance has been reduced to zero;

            third, concurrently, to the Class A-PO Certificates and Class B-4
Certificates, pro rata, based on the applicable PO Fraction and the applicable
Non-PO Fraction of such Mortgage Loans, respectively, until the Class B-4
Principal Balance has been reduced to zero;

            fourth, concurrently, to the Class A-PO Certificates and Class B-3
Certificates, pro rata, based on the applicable PO Fraction and the applicable
Non-PO Fraction of such Mortgage Loans, respectively, until the Class B-3
Principal Balance has been reduced to zero;

            fifth, concurrently, to the Class A-PO Certificates and Class B-2
Certificates, pro rata, based on the applicable PO Fraction and the applicable
Non-PO Fraction of such Mortgage Loans, respectively, until the Class B-2
Principal Balance has been reduced to zero;

            sixth, concurrently, to the Class A-PO Certificates and Class B-1
Certificates, pro rata, based on the applicable PO Fraction and the applicable
Non-PO Fraction of such Mortgage Loans, respectively, until the Class B-1
Principal Balance has been reduced to zero; and

            seventh, concurrently, to the Class A Certificates (other than the
Class A-PO Certificates) and Class A-PO Certificates, pro rata, based on the
applicable Non-PO Fraction and the applicable PO Fraction of such Mortgage
Loans, respectively.

            This allocation of Realized Losses will be effected through the
reduction of the applicable Class's Principal Balance through the operation of
the definition of Principal Balance and the provisos in the definitions of Class
B-1 Principal Balance, Class B-2 Principal Balance, Class B-3 Principal Balance,
Class B-4 Principal Balance, Class B-5 Principal Balance and Class B-6 Principal
Balance.

            (b) Any Realized Losses allocated to a Class of Class A Certificates
or Class B Certificates pursuant to Section 4.02(a) shall be allocated among the
Certificates of such Class based on their Percentage Interests.

            (c) After the Class B Principal Balance has been reduced to zero,
the interest portion of Realized Losses will be allocated among the outstanding
Classes of Class A Certificates based upon their Class A Interest Percentages.

            (d) Realized Losses allocated in accordance with this Section 4.02
will be allocated as follows: (i) Liquidated Loan Losses on Liquidated Loans for
which the Liquidation Proceeds were received during, and Bankruptcy Losses
incurred in a period corresponding to, an Unscheduled Principal Receipt Period
for Full Unscheduled Principal Receipts that is a Mid-Month Receipt Period will
be allocated on the Determination Date in the month following the month in which
such Mid-Month Receipt Period ended and (ii) Liquidated Loan Losses on
Liquidated Loans for which the Liquidation Proceeds were received during, and
Bankruptcy Losses incurred in a period corresponding to, an Unscheduled
Principal Receipt Period for Full Unscheduled Principal Receipts that is a Prior
Month Receipt Period will be allocated on the Determination Date in the second
month following the month which is such Prior Month Receipt Period.

            (e) With respect to any Distribution Date, the principal portion of
Realized Losses and recoveries attributable to previously allocated Realized
Losses allocated pursuant to this Section 4.02 will be allocated to each
Uncertificated Lower-Tier Interest in an amount equal to the amount allocated to
its respective Corresponding Upper-Tier Class or Classes as provided above.

            (f) With respect to any Distribution Date, the interest portion of
Realized Losses allocated pursuant to this Section 4.02 will be allocated to
each Uncertificated Lower-Tier Interest in the same relative proportions as
interest is allocated to such Uncertificated Lower-Tier Interest.

            Section 4.03 Paying Agent.

            (a) The Paying Agent shall establish and maintain a Payment Account,
which shall be a separate trust account (unless the Master Servicer is the
Paying Agent, in which case, the Certificate Account may be the Payment Account)
and an Eligible Account, in which the Master Servicer shall cause to be
deposited from funds in the Certificate Account or, to the extent required
hereunder, from its own funds (i) at or before 10:00 a.m., New York time, on the
Business Day preceding each Distribution Date, by wire transfer of immediately
available funds, any Periodic Advance for such Distribution Date, pursuant to
Section 3.03 and (ii) at or before 10:00 a.m., New York time, on the Business
Day preceding each Distribution Date, by wire transfer of immediately available
funds, an amount equal to the Pool Distribution Amount. The Master Servicer may
cause the Paying Agent to invest the funds in the Payment Account. Any such
investment shall be in Eligible Investments, which shall mature not later than
the Business Day preceding the related Distribution Date (unless the Eligible
Investments are obligations of the institution that maintains such account, in
which case such Eligible Investments shall mature not later than the
Distribution Date), and shall not be sold or disposed of prior to maturity. All
income and gain realized from any such investment shall be for the benefit of
the Master Servicer and shall be subject to its withdrawal or order from time to
time. The amount of any losses incurred in respect of any such investments shall
be deposited in the Payment Account by the Master Servicer out of its own funds
immediately as realized. The Paying Agent may withdraw from the Payment Account
any amount deposited in the Payment Account that was not required to be
deposited therein and may clear and terminate the Payment Account pursuant to
Section 9.01.

            (b) Wells Fargo Bank is hereby appointed as initial Paying Agent to
make distributions to Certificateholders and to make available to
Certificateholders the Distribution Date Statements and the annual statements
required by Section 4.04. The Trustee may, at any time, remove or replace the
Paying Agent, other than Wells Fargo Bank for so long as Wells Fargo Bank is
acting as the Master Servicer. If Wells Fargo Bank is no longer acting as Master
Servicer, the Master Servicer shall pay, from its own funds, the reasonable
compensation of any Paying Agent other than Wells Fargo Bank.

            The Trustee shall cause any Paying Agent that is not HSBC Bank USA,
National Association or Wells Fargo Bank to execute and deliver to the Trustee
an instrument (a "Paying Agent Agreement") in which such Paying Agent agrees
with the Trustee that such Paying Agent shall:

            (i) hold all amounts remitted to it by the Master Servicer for
      distribution to Certificateholders in trust for the benefit of
      Certificateholders until such amounts are distributed to
      Certificateholders or otherwise disposed of as herein provided;

            (ii) give the Trustee notice of any default by the Master Servicer
      in remitting any required amount;

            (iii) at any time during the continuance of any such default, upon
      the written request of the Trustee, forthwith pay to the Trustee all
      amounts held in trust by such Paying Agent; and

            (iv) provide to the Master Servicer the assessment of compliance and
      accountants report provided for in Section 3.11 with respect to the
      Servicing Criteria set forth in Item 1122(d) of Regulation AB applicable
      to the duties of the Paying Agent.

            Section 4.04 Statements to Certificateholders; Reports to the
Trustee and the Depositor.

            (a) On each Distribution Date, the Master Servicer shall make
available in accordance with subsection (b) of this Section 4.04 to each Holder
of a Certificate, the Trustee, the Paying Agent and the Depositor a statement
(the "Distribution Date Statement") setting forth:

            (i) the applicable Determination Date, the applicable Record Date
      and the actual Distribution Date;

            (ii) the amount of such distribution to Holders of each Class of
      Class A Certificates allocable to principal, separately identifying the
      aggregate amount of any Unscheduled Principal Receipts and Liquidation
      Proceeds included therein and the Principal Balance of each Class of Class
      A Certificates;

            (iii) (A) the amount of such distribution to Holders of each Class
      of Class A Certificates allocable to interest, (B) the amount of the
      Current Class A Interest Distribution Amount allocated to each Class of
      Class A Certificates, (C) any Interest Shortfall Amounts arising with
      respect to such Distribution Date and any remaining Class A Unpaid
      Interest Shortfall with respect to each Class after giving effect to such
      distribution, (D) the amount of any Non-Supported Interest Shortfalls
      allocated to each Class of Class A Certificates for such Distribution Date
      and (E) the amount of any Relief Act Shortfall allocated to each Class of
      Class A Certificates for such Distribution Date;

            (iv) the amount of such distribution to Holders of each Class of
      Class B Certificates allocable to principal, separately identifying the
      aggregate amount of any Unscheduled Principal Receipts and Liquidation
      Proceeds included therein and the Principal Balance of each Class of Class
      B Certificates;

            (v) (A) the amount of such distribution to Holders of each Class of
      Class B Certificates allocable to interest, (B) the amount of the Current
      Class B Interest Distribution Amount allocated to each Class of Class B
      Certificates, (C) any Class B Interest Shortfall Amounts arising with
      respect to such Distribution Date and any remaining Class B Unpaid
      Interest Shortfall with respect to each Class of Class B Certificates
      after giving effect to such distribution, (D) the amount of any
      Non-Supported Interest Shortfall allocated to each Class of Class B
      Certificates for such Distribution Date and (E) the amount of any Relief
      Act Shortfall allocated to each Class of Class B Certificates for such
      Distribution Date;

            (vi) the amount of any Periodic Advance by or reimbursed to any
      Servicer, the Master Servicer or the Trustee pursuant to the Servicing
      Agreements or this Agreement;

            (vii) the number and aggregate principal balance of Mortgage Loans
      outstanding, the weighted average Mortgage Interest Rate and weighted
      average remaining term to maturity of the Mortgage Loans outstanding and
      the cumulative prepayment amounts, in each case, as of the preceding
      Determination Date;

            (viii) the number and aggregate principal balances of the Mortgage
      Loans by range of current Mortgage Interest Rates;

            (ix) the pool factors for such Distribution Date;

            (x) the beginning and ending balance of the Certificate Account;

            (xi) the Class A Principal Balance, the Principal Balance of each
      Class of Class A Certificates, the Class B Principal Balance and the
      Principal Balance of each Class of Class B Certificates prior to and after
      giving effect to the distributions of principal made, and the principal
      portion of Realized Losses, if any, allocated with respect to such
      Distribution Date;

            (xii) the Adjusted Pool Amount, the Adjusted Pool Amount (Non-PO
      Portion), the Adjusted Pool Amount (PO Portion), the Pool Scheduled
      Principal Balance of the Mortgage Loans for such Distribution Date, the
      aggregate Scheduled Principal Balance of the Discount Mortgage Loans for
      such Distribution Date;

            (xiii) the aggregate Scheduled Principal Balances of the Mortgage
      Loans serviced by Wells Fargo Bank in its capacity as Servicer and,
      collectively, by the Other Servicers as of such Distribution Date;

            (xiv) the Class A Percentage for such Distribution Date;

            (xv) the Class A Prepayment Percentage for such Distribution Date;

            (xvi) the Class B-1, Class B-2, Class B-3, Class B-4, Class B-5 and
      Class B-6 Percentages for such Distribution Date;

            (xvii) the Class B-1, Class B-2, Class B-3, Class B-4, Class B-5 and
      Class B-6 Prepayment Percentages for such Distribution Date;

            (xviii) the number and aggregate principal balances of the Mortgage
      Loans (A) delinquent (exclusive of Mortgage Loans in foreclosure or
      bankruptcy), grouping such delinquent Mortgage Loans in 30 day increments,
      up to 180 days delinquent (determined in accordance with the Mortgage
      Bankers' Association delinquency methodology), (B) in foreclosure, as of
      the close of business on the last day of the calendar month preceding the
      Distribution Date and (C) in bankruptcy as of the close of business on the
      last day of the calendar month preceding the Distribution Date;

            (xix) the number and aggregate principal balances of the Mortgage
      Loans that are REO Mortgage Loans as of the Determination Date immediately
      preceding such Distribution Date;

            (xx) the aggregate amount of Realized Losses incurred during the
      preceding calendar month;

            (xxi) any expenses or indemnification amounts paid by the Trust, the
      specific purpose of each payment and the parties to whom the payments were
      made;

            (xxii) the amount by which the Principal Balance of each Class of
      Class B Certificates has been reduced as a result of Realized Losses
      allocated as of such Distribution Date;

            (xxiii) the amount of the aggregate Servicing Fees and Master
      Servicing Fees paid (and not previously reported) with respect to the
      related Distribution Date and the amount by which the aggregate Available
      Master Servicer Compensation has been reduced by the Prepayment Interest
      Shortfall for the related Distribution Date;

            (xxiv) the amount of PMI Advances made by a Servicer, if any;

            (xxv) the Class A Pass-Through Rate for each Class of Class A
      Certificates and the Class B Pass-Through Rate for each Class of Class B
      Certificates;

            (xxvi) in the case of each Class of Interest Only Certificates, the
      applicable Notional Amount, if any;

            (xxvii) the Yield Maintenance Agreement Payments received from the
      Counterparty;

            (xxviii) the Class A-PO Deferred Amount, if any;

            (xxix) any material modifications, extensions or waivers to Mortgage
      Loan terms, fees, penalties or payments since the previous Distribution
      Date;

            (xxx) any material breaches of representations and warranties
      relating to the Mortgage Loans or material breaches of transaction
      covenants;

            (xxxi) if any of the Mortgage Loans have prepayment penalties, the
      aggregate amount of any prepayment penalties paid; and

            (xxxii) any other customary information as is required to enable
      Certificateholders to prepare their tax returns.

            In the case of information furnished with respect to a Class of
Class A Certificates pursuant to clauses (ii) and (iii) above and with respect
to a Class of Class B Certificates pursuant to clauses (iv) and (v) above, the
amounts shall be expressed as a dollar amount per Class A or Class B Certificate
(other than the Residual Certificate) with a $1,000 Denomination, and as a
dollar amount per Residual Certificate with a $100 Denomination.

            Within a reasonable period of time after the end of each calendar
year, the Paying Agent shall, upon request, furnish or cause to be furnished to
each Person who at any time during the calendar year was the Holder of a
Certificate a statement containing the information set forth in clauses (ii) and
(iii)(A) above in the case of a Class A Certificateholder and the information
set forth in clauses (iv) and (v)(A) above in the case of a Class B
Certificateholder aggregated for such calendar year or applicable portion
thereof during which such Person was a Certificateholder. Such obligation of the
Paying Agent shall be deemed to have been satisfied to the extent that
substantially comparable information shall be provided by the Master Servicer or
the Trustee pursuant to any requirements of the Code from time to time in force.

            Unless the Master Servicer is acting as the Paying Agent, prior to
the close of business on the second Business Day preceding each Distribution
Date, the Master Servicer shall furnish a statement to any Paying Agent (the
information in such statement to be made available to Certificateholders by the
Paying Agent on written request) setting forth the Class A Distribution Amount
with respect to each Class of Class A Certificates and the Class B Distribution
Amount with respect to each Class of Class B Certificates. The determination by
the Master Servicer of such amounts shall, in the absence of obvious error, be
presumptively deemed to be correct for all purposes hereunder and the Trustee
and the Paying Agent shall be protected in relying upon the same without any
independent check or verification.

            In addition to the Distribution Date Statements and the annual
statements required pursuant to this Section 4.04(a), the Paying Agent shall
make available upon request to each Holder and each proposed transferee of a
Class B-4, Class B-5 or Class B-6 Certificate such additional information, if
any, as may be required to permit the proposed transfer to be effected pursuant
to Rule 144A, which information shall be provided on a timely basis to the
Paying Agent by the Master Servicer.

            (b) The Master Servicer's responsibility for disbursing the
information set forth in subsection (a) of this Section 4.04 to each Holder of a
Certificate, the Depositor and other interested parties is limited to the
availability, timeliness and the accuracy of the information provided by each
Servicer. The Master Servicer will make a copy of each Distribution Date
Statement provided pursuant to this Section 4.04 (and, at its option, any
additional files containing the same information in an alternative format)
available each month to Certificateholders and other interested parties, and
other parties to this Agreement via the Master Servicer's internet website,
which in the case of Wells Fargo Bank, is located at "www.ctslink.com." In
addition, the Paying Agent shall provide copies of the Distribution Date
Statement and the annual statements required pursuant to Section 4.04(a) to
Persons making written requests therefor at its Corporate Trust Office.
Assistance in using the internet website can be obtained by calling the Master
Servicer's customer service desk, which in the case of Wells Fargo Bank is at
(301) 815-6600. Parties that are unable to use the above distribution method are
entitled to have a paper copy mailed to them via first class mail by calling the
customer service desk and indicating such. The Master Servicer shall have the
right to change the way the Distribution Date Statement is distributed in order
to make such distribution more convenient and/or more accessible and the Master
Servicer shall provide timely and adequate notification to the
Certificateholders and the parties to this Agreement regarding any such changes.

            The Master Servicer shall also be entitled to rely on but shall not
be responsible for the content or accuracy of any information provided by third
parties for purposes of preparing the Distribution Date Statement and may affix
thereto any disclaimer it deems appropriate in its reasonable discretion
(without suggesting liability on the part of any other party hereto).

            Section 4.05 Grantor Trust Administration

            (a) The Grantor Trust is a WHFIT that is a NMWHFIT. The Master
Servicer will report as required under the WHFIT Regulations to the extent such
information as is reasonably necessary to enable the Master Servicer to do so,
and is not in its possession, is provided to the Master Servicer on a timely
basis. The Master Servicer is hereby directed to assume that DTC is the only
"middleman" (as such term is defined in the WHFIT Regulations) unless the
Depositor provides the Master Servicer with the identities of other "middlemen"
that are Certificateholders. The Master Servicer shall be entitled to rely on
the first sentence of this subparagraph (a) and shall be entitled to
indemnification in accordance with the terms of this Agreement in the event that
the Internal Revenue Service makes a determination that the first sentence of
this subparagraph (a) is incorrect.

            (b) The Master Servicer, in its discretion, will report required
WHFIT information using either the cash or accrual method, except to the extent
the WHFIT Regulations specifically require a different method. The Master
Servicer will be under no obligation to determine whether any Certificateholder
or other beneficial owner of a Certificate, to the extent the Master Servicer
knows of any other beneficial owner of a Certificate, uses the cash or accrual
method. The Master Servicer will make available information as required by the
WHFIT Regulations to Certificateholders annually. In addition, the Master
Servicer will not be responsible or liable for providing subsequently amended,
revised or updated information to any Certificateholder, unless requested by the
Certificateholder.

            (c) The Master Servicer shall not be liable for failure to meet the
reporting requirements of the WHFIT Regulations nor for any penalties thereunder
if such failure is due to: (i) the lack of reasonably necessary information
being provided to the Master Servicer, (ii) incomplete, inaccurate or untimely
information being provided to the Master Servicer or (iii) the inability of the
Master Servicer, after good faith efforts, to alter its existing information
reporting systems to capture information necessary to fully comply with the
WHFIT Regulations for the 2007 calendar year. Absent receipt of information
regarding any sale of securities, including the price, amount of proceeds and
date of sale from the beneficial owner thereof or the Depositor, the Master
Servicer will assume there is no secondary market trading of WHFIT interests.

            (d) To the extent required by the WHFIT Regulations, the Master
Servicer will use reasonable efforts to publish on an appropriate website the
CUSIP Numbers for the Certificates that represent ownership of a WHFIT. The
CUSIP Numbers so published will represent the Rule 144A CUSIP Numbers. The
Master Servicer will make reasonable good faith efforts to keep the website
accurate and updated to the extent CUSIP Numbers have been received. The Master
Servicer will not be liable for investor reporting delays that result from the
receipt of inaccurate or untimely CUSIP Number information.

            (e) The Master Servicer shall be entitled to additional reasonable
compensation for changes in reporting required in respect of the WHFIT
Regulations that arise as a result of a change in the WHFIT Regulations or a
change in interpretation of the WHFIT Regulations by the IRS, if such change
requires, in the Master Servicer's sole discretion, a material increase in the
Master Servicer's reporting obligations in respect of the related Grantor
Trust.

            Section 4.06 Calculation of Amounts; Binding Effect of
Interpretations and Actions of Master Servicer.

            The Master Servicer will compute the amount of all distributions to
be made on the Certificates and all losses to be allocated to the Certificates.
In the event that the Master Servicer concludes that any ambiguity or
uncertainty exists in any provisions of this Agreement relating to distributions
to be made on the Certificates, the allocation of losses to the Certificates or
otherwise, the interpretation of such provisions and any actions taken by the
Master Servicer in good faith to implement such interpretation shall be binding
upon Certificateholders.

            Section 4.07 Reserve Fund

            (a) The Master Servicer shall establish and maintain the Reserve
Fund, held in trust for the benefit of the Holders of the Class A-5
Certificates. The Master Servicer shall deposit in the Reserve Fund on the date
received by it, any Yield Maintenance Agreement Payment received from the
Counterparty for the related Distribution Date. Funds on deposit in the Reserve
Fund shall remain uninvested. On each Distribution Date (other than the
Distribution Date in April 2007), the Master Servicer shall withdraw from the
Reserve Fund any Yield Maintenance Agreement Payment received in respect of such
Distribution Date and any Excess Funds in the Reserve Fund and shall distribute
such amounts to the Class A-5 Certificates in an amount up to the sum of the
Yield Maintenance Amount for such Distribution Date and any Yield Maintenance
Amount Shortfalls for prior Distribution Dates. Any amounts remaining in the
Reserve Fund after the earlier of (i) the date on which the Principal Balance of
the Class A-5 Certificates is reduced to zero (after payment of the Yield
Maintenance Amount for such date and the amount of any Yield Maintenance Amount
Shortfalls from previous Distribution Dates not yet paid) or (ii) the
termination of the Trust Estate shall be distributed by the Master Servicer to
Greenwich Capital Markets, Inc.

            (b) The Master Servicer shall account for the Reserve Fund and the
Yield Maintenance Agreement and the rights with respect thereto as assets of the
Trust Estate and not as assets of either REMIC created pursuant to this
Agreement. The beneficial owner of the Reserve Fund is Greenwich Capital
Markets, Inc. The Master Servicer shall treat the portions of the Trust Estate
consisting of the Reserve Fund and the Yield Maintenance Agreement and rights
with respect thereto as a "grantor trust" under the Code, and the provisions
hereof shall be interpreted consistently with this treatment. The Master
Servicer shall make available upon request (i) to the Holders of the Class A-5
Certificates and (ii) to Greenwich Capital Markets, Inc., and shall file or
cause to be filed with the Internal Revenue Service together with any other
information or form as may be applicable, their allocable shares of income and
expenses with respect to the property held by the Grantor Trust, at the time or
times and in the manner required by the Code.

            Any amounts in the Reserve Fund paid by the Master Servicer pursuant
to this Section 4.07 to the Class A-5 Certificates, shall be accounted for by
the Master Servicer as amounts paid to the Class A-5 Certificates from the
Grantor Trust. In addition, the Master Servicer shall account for the rights of
the Class A-5 Certificates to receive amounts from the Reserve Fund as rights in
a limited recourse interest rate cap contract written by the Counterparty in
favor of the Class A-5 Certificates.

<PAGE>

                                   ARTICLE V

                                THE CERTIFICATES

            Section 5.01 The Certificates.

            (a) The Class A-1, Class A-2, Class A-3, Class A-4, Class A-5, Class
A-6, Class A-7, Class A-8, Class A-9, Class A-10, Class A-11, Class A-12, Class
A-13, Class A-14, Class A-15, Class A-16, Class A-17, Class A-18, Class A-19,
Class A-20, Class A-21, Class A-PO and Class B Certificates shall be issued only
in minimum Denominations of a Single Certificate and, except for the Class A-10
and Class A-R Certificates, integral multiples of $1 in excess thereof and shall
be substantially in the respective forms set forth as Exhibits A-1, A-2, A-3,
A-4, A-5, A-6, A-7, A-8, A-9, A-10, A-11, A-12, A-13, A-14, A-15, A-16, A-17,
A-18, A-19, A-20, A-21, A-PO, A-R, B-1, B-2, B-3, B-4, B-5, B-6 and C (reverse
side of Certificates) hereto. On original issue the Certificates shall be
executed and delivered by the Paying Agent to or upon the order of the Depositor
upon receipt by the Trustee or the Custodian of the documents specified in
Section 2.01(a). The aggregate principal portion evidenced by the Class A and
Class B Certificates shall be the sum of the amounts specifically set forth in
the respective Certificates. The Certificates shall be executed by manual or
facsimile signature on behalf of the Paying Agent by any Responsible Officer
thereof. Certificates bearing the manual or facsimile signatures of individuals
who were at any time the proper officers of the Paying Agent shall bind the
Paying Agent notwithstanding that such individuals or any of them have ceased to
hold such offices prior to the countersigning of such Certificates and delivery
of such Certificates or did not hold such offices at the date of such
Certificates. No Certificate shall be entitled to any benefit under this
Agreement, or be valid for any purpose, unless manually countersigned by a
Responsible Officer of the Authenticating Agent, or unless there appears on such
Certificate a certificate of authentication executed by the Authenticating Agent
by manual signature, and such countersignature or certificate upon a Certificate
shall be conclusive evidence, and the only evidence, that such Certificate has
been duly authenticated and delivered hereunder. All Certificates shall be dated
the date of their authentication.

            Until such time as Definitive Certificates are issued pursuant to
Section 5.07, each Book-Entry Certificate shall bear the following legend:

            "Unless this certificate is presented by an authorized
representative of [the Clearing Agency] to the Depositor or its agent for
registration of transfer, exchange or payment, and any certificate issued is
registered in the name of [the Clearing Agency] or such other name as requested
by an authorized representative of [the Clearing Agency] and any payment is made
to [the Clearing Agency], any transfer, pledge or other use hereof for value or
otherwise by or to any person is wrongful since the registered owner hereof,
[the Clearing Agency], has an interest herein."

            (b) Upon original issuance, the Book-Entry Certificates shall be
issued in the form of one or more typewritten certificates, to be delivered to
The Depository Trust Company, the initial Clearing Agency, by, or on behalf of,
the Depositor or to, and deposited with the Certificate Custodian, on behalf of
The Depository Trust Company, if directed to do so pursuant instructions from
The Depository Trust Company. Such Certificates shall initially be registered in
the Certificate Register in the name of the nominee of the initial Clearing
Agency, and no Beneficial Owner will receive a definitive certificate
representing such Beneficial Owner's interest in the Book-Entry Certificates,
except as provided in Section 5.07. Unless and until definitive, fully
registered certificates ("Definitive Certificates") have been issued to
Beneficial Owners pursuant to Section 5.07:

            (i) the provisions of this Section 5.01(b) shall be in full force
      and effect;

            (ii) the Depositor, the Master Servicer, the Certificate Registrar,
      the Paying Agent and the Trustee may deal with the Clearing Agency for all
      purposes (including the making of distributions on the Book-Entry
      Certificates and the taking of actions by the Holders of Book-Entry
      Certificates) as the authorized representative of the Beneficial Owners;

            (iii) to the extent that the provisions of this Section 5.01(b)
      conflict with any other provisions of this Agreement, the provisions of
      this Section 5.01(b) shall control;

            (iv) the rights of Beneficial Owners shall be exercised only through
      the Clearing Agency and shall be limited to those established by law, the
      rules, regulations and procedures of the Clearing Agency and agreements
      between such Beneficial Owners and the Clearing Agency and/or the Clearing
      Agency Participants, and all references in this Agreement to actions by
      Certificateholders shall, with respect to the Book-Entry Certificates,
      refer to actions taken by the Clearing Agency upon instructions from the
      Clearing Agency Participants, and all references in this Agreement to
      distributions, notices, reports and statements to Certificateholders
      shall, with respect to the Book-Entry Certificates, refer to
      distributions, notices, reports and statements to the Clearing Agency or
      its nominee, as registered holder of the Book-Entry Certificates, as the
      case may be, for distribution to Beneficial Owners in accordance with the
      procedures of the Clearing Agency; and

            (v) the initial Clearing Agency will make book-entry transfers among
      the Clearing Agency Participants and receive and transmit distributions of
      principal and interest on the Certificates to the Clearing Agency
      Participants, for distribution by such Clearing Agency Participants to the
      Beneficial Owners or their nominees.

            For purposes of any provision of this Agreement requiring or
permitting actions with the consent of, or at the direction of, Holders of
Book-Entry Certificates evidencing specified Voting Interests, such direction or
consent shall be given by Beneficial Owners having the requisite Voting
Interests, acting through the Clearing Agency.

            Unless and until Definitive Certificates have been issued to
Beneficial Owners pursuant to Section 5.07, copies of the Distribution Date
Statements shall be available to Beneficial Owners upon written request to the
Paying Agent at its Corporate Trust Office.

            Section 5.02 Registration of Certificates.

            (a) The Certificate Registrar shall cause to be kept at one of the
offices or agencies to be maintained in accordance with the provisions of
Section 5.06 a Certificate Register in which, subject to such reasonable
regulations as it may prescribe, the Certificate Registrar shall provide for the
registration of Certificates and of transfers and exchanges of Certificates as
herein provided. The Master Servicer shall act as, or shall appoint, a
Certificate Registrar for the purpose of registering Certificates and transfers
and exchanges of Certificates as herein provided.

            Upon surrender for registration of transfer of any Certificate at
any office or agency maintained for such purpose pursuant to Section 5.06 (and
subject to the provisions of this Section 5.02) the Paying Agent shall execute,
and shall date, countersign (or cause the Authenticating Agent to countersign)
and deliver, in the name of the designated transferee or transferees, one or
more new Certificates of a like aggregate principal portion or Percentage
Interest and of the same Class.

            At the option of the Certificateholders, Certificates may be
exchanged for other Certificates of authorized Denominations of a like aggregate
principal portion or Percentage Interest and of the same Class upon surrender of
the Certificates to be exchanged at any such office or agency. Whenever any
Certificates are so surrendered for exchange, the Paying Agent shall execute,
and shall date, countersign (or cause the Authenticating Agent to countersign)
and deliver, the Certificates which the Certificateholder making the exchange is
entitled to receive. Every Certificate presented or surrendered for transfer or
exchange shall (if so required by the Certificate Registrar or the Paying Agent)
be duly endorsed by, or be accompanied by a written instrument of transfer in
form satisfactory to the Certificate Registrar, duly executed by the Holder
thereof or his attorney duly authorized in writing.

            No service charge shall be made for any transfer or exchange of
Certificates, but the Certificate Registrar may require payment of a sum
sufficient to cover any tax or governmental charge that may be imposed in
connection with any transfer or exchange of Certificates.

            All Certificates surrendered for transfer and exchange shall be
canceled by the Certificate Registrar, the Paying Agent or the Authenticating
Agent in accordance with their standard procedures.

            (b) No transfer of a Class B-4, Class B-5 or Class B-6 Certificate
shall be made unless the registration requirements of the 1933 Act and any
applicable State securities laws are complied with, or such transfer is exempt
from the registration requirements under said Act and laws. In the event that a
transfer is to be made in reliance upon an exemption from said Act or laws, the
Master Servicer shall require the transferee (other than an affiliate of the
Depositor on the Closing Date) to execute an investment letter in the form of
Exhibit J hereto certifying to the Depositor and the Master Servicer the facts
surrounding such transfer, which investment letter shall not be an expense of
the Depositor or the Master Servicer. The Holder of a Class B-4, Class B-5 or
Class B-6 Certificate desiring to effect such transfer shall, and does hereby
agree to, indemnify the Trustee, the Depositor, the Master Servicer and any
Paying Agent against any liability that may result if the transfer is not so
exempt or is not made in accordance with such federal and state laws. Neither
the Depositor nor the Master Servicer is under an obligation to register the
Class B-4, Class B-5 or Class B-6 Certificates under said Act or any other
securities law. For the purposes of this Section 5.02 (b) the representations
required in any investment letter (in substantially the form attached hereto as
Exhibit J for any transfer of a Class B-4, Class B-5 or Class B-6 Certificate)
shall be deemed to have been made in connection with the transfer of any Class
B-4, Class B-5 or Class B-6 Certificate that is a Book-Entry Certificate.

            (c) No transfer of a Class B-4, Class B-5 or Class B-6 Certificate
shall be made unless the Master Servicer and the Depositor shall have received
(i) a representation letter from the transferee in the form of Exhibit J hereto,
to the effect that either (a) such transferee is not an employee benefit plan or
other retirement arrangement subject to Title I of ERISA or Code Section 4975,
or a governmental plan, as defined in Section 3(32) of ERISA, subject to any
federal, state or local law ("Similar Law") which is to a material extent
similar to the foregoing provisions of ERISA or the Code (collectively, a
"Plan") and is not a person acting on behalf of or using the assets of any such
Plan, which representation letter shall not be an expense of the Depositor or
the Master Servicer or (b) if such transferee is an insurance company, (A) the
source of funds used to purchase the Class B-4, Class B-5 or Class B-6
Certificate is an "insurance company general account" (as such term is defined
in Section V(e) of Prohibited Transaction Class Exemption 95-60 ("PTE 95-60"),
60 Fed. Reg. 35925 (July 12, 1995)), (B) there is no Plan with respect to which
the amount of such general account's reserves and liabilities for the
contract(s) held by or on behalf of such Plan and all other Plans maintained by
the same employer (or affiliate thereof as defined in Section V(a)(1) of PTE
95-60) or by the same employee organization exceeds 10% of the total of all
reserves and liabilities of such general account (as such amounts are determined
under Section I(a) of PTE 95-60) at the date of acquisition and (C) the purchase
and holding of such Class B-4, Class B-5 or Class B-6 Certificate is covered by
Sections I and III of PTE 95-60 or (ii) in the case of any such Class B-4, Class
B-5 or Class B-6 Certificate presented for registration in the name of a Plan,
or a trustee of any such Plan, (A) an Opinion of Counsel satisfactory to the
Master Servicer and the Depositor to the effect that the purchase or holding of
such Class B-4, Class B-5 or Class B-6 Certificate will not constitute or result
in a non-exempt prohibited transaction within the meaning of ERISA, Section 4975
of the Code or Similar Law and will not subject the Depositor or the Master
Servicer to any obligation in addition to those undertaken in this Agreement,
which Opinion of Counsel shall not be an expense of the Depositor or the Master
Servicer and (B) such other opinions of counsel, Officer's Certificates and
agreements as the Depositor or the Master Servicer may require in connection
with such transfer, which opinions of counsel, Officer's Certificates and
agreements shall not be an expense of the Depositor or the Master Servicer. The
applicable representation set forth in clause (i) shall be deemed to have been
made to the Depositor and Master Servicer by the acceptance by a transferee of
the beneficial interest in any such Class B-4, Class B-5 and Class B-6
Certificates, unless the Depositor and Master Servicer shall have received from
the transferee either an alternative representation acceptable in form and
substance to the Depositor and Master Servicer or the Opinion of Counsel and
other documentation set forth in clause (ii). The Class B-4, Class B-5 and Class
B-6 Certificates shall bear a legend referring to the foregoing restrictions
contained in this paragraph.

            (d) No legal or beneficial interest in all or any portion of the
Residual Certificate may be transferred directly or indirectly to a
"disqualified organization" within the meaning of Code Section 860E(e)(5) or an
agent of a disqualified organization (including a broker, nominee, or
middleman), to a Plan or a Person acting on behalf of or investing the assets of
a Plan (such Plan or Person, an "ERISA Prohibited Holder") or to an individual,
corporation, partnership or other person unless such transferee (i) is not a
Non-U.S. Person or (ii) is a Non-U.S. Person that holds the Residual Certificate
in connection with the conduct of a trade or business within the United States
and has furnished the transferor and the Master Servicer with an effective
Internal Revenue Service Form W-8ECI or (iii) is a Non-U.S. Person that has
delivered to both the transferor and the Master Servicer an opinion of a
nationally recognized tax counsel to the effect that the transfer of the
Residual Certificate to it is in accordance with the requirements of the Code
and the regulations promulgated thereunder and that such transfer of the
Residual Certificate will not be disregarded for federal income tax purposes
(any such person who is not covered by clauses (i), (ii) or (iii) above being
referred to herein as a "Non-permitted Foreign Holder"), and any such purported
transfer shall be void and have no effect. The Paying Agent shall not execute,
and shall not countersign (or cause the Authenticating Agent to countersign) and
deliver, a new Residual Certificate in connection with any such transfer to a
disqualified organization or agent thereof (including a broker, nominee or
middleman), an ERISA Prohibited Holder or a Non-permitted Foreign Holder, and
neither the Certificate Registrar nor the Paying Agent shall accept a surrender
for transfer or registration of transfer, or register the transfer of, the
Residual Certificate, unless the transferor shall have provided to the Master
Servicer an affidavit, substantially in the form attached as Exhibit H hereto,
signed by the transferee, to the effect that the transferee is not such a
disqualified organization, an agent (including a broker, nominee, or middleman)
for any entity as to which the transferee has not received a substantially
similar affidavit, an ERISA Prohibited Holder or a Non-permitted Foreign Holder,
which affidavit shall contain the consent of the transferee to any such
amendments of this Agreement as may be required to further effectuate the
foregoing restrictions on transfer of the Residual Certificate to disqualified
organizations, ERISA Prohibited Holders or Non-permitted Foreign Holders. Such
affidavit shall also contain the statement of the transferee that (i) the
transferee has historically paid its debts as they have come due and intends to
do so in the future, (ii) the transferee understands that it may incur
liabilities in excess of cash flows generated by the residual interest, (iii)
the transferee intends to pay taxes associated with holding the residual
interest as they become due (iv) the transferee will not cause income from the
Residual Certificate to be attributable to a foreign permanent establishment or
fixed base, within the meaning of an applicable income tax treaty, of such
transferee or any other Person, and (v) the transferee will not transfer the
Residual Certificate to any Person who does not provide an affidavit
substantially in the form attached as Exhibit H hereto.

            The affidavit described in the preceding paragraph, if not executed
in connection with the initial issuance of the Residual Certificate, shall be
accompanied by a written statement in the form attached as Exhibit I hereto,
signed by the transferor, to the effect that as of the time of the transfer, the
transferor has no actual knowledge that the transferee is a disqualified
organization, ERISA Prohibited Holder or Non-permitted Foreign Holder, and has
no knowledge or reason to know that the statements made by the transferee with
respect to clauses (i) and (iii) of the last sentence of the preceding paragraph
are not true. The Residual Certificate shall bear a legend referring to the
foregoing restrictions contained in this paragraph and the preceding paragraph.

            Upon actual knowledge of a Master Servicing Officer or a Responsible
Officer of the Paying Agent that any legal or beneficial interest in any portion
of the Residual Certificate has been transferred, directly or indirectly, to a
disqualified organization or agent thereof (including a broker, nominee, or
middleman) in contravention of the foregoing restrictions, (i) such transferee
shall be deemed to hold the Residual Certificate in constructive trust for the
last transferor who was not a disqualified organization or agent thereof, and
such transferor shall be restored as the owner of such Residual Certificate as
completely as if such transfer had never occurred, provided that the Master
Servicer may, but is not required to, recover any distributions made to such
transferee with respect to the Residual Certificate, and (ii) the Master
Servicer agrees to furnish to the Internal Revenue Service and to any transferor
of the Residual Certificate or such agent (within 60 days of the request
therefor by the transferor or agent) such information necessary to the
application of Code Section 860E(e) as may be required by the Code, including
but not limited to the present value of the total anticipated excess inclusions
with respect to the Residual Certificate (or portion thereof) for periods after
such transfer. At the election of the Master Servicer, the cost to the Master
Servicer of computing and furnishing such information may be charged to the
transferor or such agent referred to above; however, the Master Servicer shall
in no event be excused from furnishing such information.

            Section 5.03 Mutilated, Destroyed, Lost or Stolen Certificates.

            If (i) any mutilated Certificate is surrendered to the Paying Agent,
the Certificate Registrar or the Authenticating Agent, or the Paying Agent, the
Certificate Registrar or the Authenticating Agent receives evidence to its
satisfaction of the destruction, loss or theft of any Certificate, and (ii)
there is delivered to the Paying Agent, the Certificate Registrar or the
Authenticating Agent such security or indemnity as may be required by them to
hold each of them harmless, then, in the absence of notice to the Paying Agent,
the Certificate Registrar or the Authenticating Agent that such Certificate has
been acquired by a bona fide purchaser, the Paying Agent shall execute and
countersign (or cause the Authenticating Agent to countersign) and deliver, in
exchange for or in lieu of any such mutilated, destroyed, lost or stolen
Certificate, a new Certificate of like tenor and principal portion or Percentage
Interest and of the same Class. Upon the issuance of any new Certificate under
this Section, the Paying Agent or the Certificate Registrar may require the
payment of a sum sufficient to cover any tax or other governmental charge that
may be imposed in relation thereto and any other expense (including the fees and
expenses of the Paying Agent or the Authenticating Agent) in connection
therewith. Any duplicate Certificate issued pursuant to this Section shall
constitute complete and indefeasible evidence of ownership in the Trust Estate,
as if originally issued, whether or not the lost, stolen, or destroyed
Certificate shall be found at any time.

            Section 5.04 Persons Deemed Owners.

            Prior to the due presentation of a Certificate for registration of
transfer, the Depositor, the Master Servicer, the Trustee, the Paying Agent, the
Certificate Registrar and any agent of the Depositor, the Master Servicer, the
Trustee, the Paying Agent or the Certificate Registrar may treat the Person in
whose name any Certificate is registered as the owner of such Certificate for
the purpose of receiving distributions pursuant to Section 4.01, and for all
other purposes whatsoever, and neither the Depositor, the Master Servicer, the
Trustee, the Certificate Registrar, the Paying Agent nor any agent of the
Depositor, the Master Servicer, the Trustee, the Certificate Registrar or the
Paying Agent shall be affected by notice to the contrary.

            Section 5.05 Access to List of Certificateholders' Names and
Addresses.

            (a) If the Paying Agent is not acting as Certificate Registrar, the
Certificate Registrar shall furnish or cause to be furnished to the Paying
Agent, within 15 days after receipt by the Certificate Registrar of a request by
the Paying Agent in writing, a list, in such form as the Paying Agent may
reasonably require, of the names and addresses of the Certificateholders of each
Class as of the most recent Record Date.

            (b) If five or more Certificateholders (hereinafter referred to as
"applicants") apply in writing to the Certificate Registrar, and such
application states that the applicants desire to communicate with other
Certificateholders with respect to their rights under this Agreement or under
the Certificates and is accompanied by a copy of the communication which such
applicants propose to transmit, then the Certificate Registrar shall, within
five Business Days following the receipt of such application, afford such
applicants access during normal business hours to the most recent list of
Certificateholders held by the Certificate Registrar.

            (c) Every Certificateholder, by receiving and holding a Certificate,
agrees with the Depositor, the Master Servicer, the Certificate Registrar, the
Paying Agent and the Trustee that neither the Depositor, the Master Servicer,
the Certificate Registrar, the Paying Agent nor the Trustee shall be held
accountable by reason of the disclosure of any such information as to the names,
addresses and Percentage Interests of the Certificateholders hereunder,
regardless of the source from which such information was delivered.

            Section 5.06 Maintenance of Office or Agency.

            The Certificate Registrar will maintain, at its expense, an office
or agency where Certificates may be surrendered for registration of transfer or
exchange and where notices and demands to or upon the Certificate Registrar in
respect of the Certificates and this Agreement may be served. The Certificate
Registrar initially designates the Corporate Trust Office of the Certificate
Registrar, if any, as its offices and agencies for said purposes.

            Section 5.07 Definitive Certificates.

            If (A) the Clearing Agency advises the Paying Agent in writing that
the Clearing Agency is no longer willing or able properly to discharge its
responsibilities as depository with respect to the Book-Entry Certificates, and
(B) the Depositor is unable to locate a qualified successor, the Paying Agent
shall notify the Beneficial Owners, through the Clearing Agency, of the
occurrence of any such event and of the availability of Definitive Certificates
to Beneficial Owners requesting the same. Upon surrender to the Paying Agent by
the Clearing Agency of the Certificates held of record by its nominee,
accompanied by reregistration instructions and directions to execute and
authenticate new Certificates from the Depositor, the Paying Agent shall execute
and cause the Authenticating Agent to countersign Definitive Certificates for
delivery at its Corporate Trust Office. The Depositor shall arrange for, and
will bear all costs of, the printing and issuance of such Definitive
Certificates. Except with the consent of the Depositor, the Paying Agent shall
not execute or cause the Authenticating Agent to countersign Definitive
Certificates in exchange for Book-Entry Certificates except as set forth above.
Neither the Depositor, the Master Servicer nor the Paying Agent shall be liable
for any delay in delivery of such instructions by the Clearing Agency and may
conclusively rely on, and shall be protected in relying on, such instructions.

            Section 5.08 Notices to Clearing Agency.

            Whenever notice or other communication to the Holders of Book-Entry
Certificates is required under this Agreement, unless and until Definitive
Certificates shall have been issued to Beneficial Owners pursuant to Section
5.07, the Paying Agent shall give all such notices and communications specified
herein to be given to Holders of Book-Entry Certificates to the Clearing Agency.

<PAGE>

                                   ARTICLE VI

                      THE DEPOSITOR AND THE MASTER SERVICER

            Section 6.01 Liability of the Depositor and the Master Servicer.

            The Depositor and the Master Servicer shall each be liable in
accordance herewith only to the extent of the obligations specifically imposed
by this Agreement and undertaken hereunder by the Depositor and the Master
Servicer.

            Section 6.02 Merger or Consolidation of the Depositor or the Master
Servicer.

            Subject to the following paragraph (a) the Depositor will keep in
full effect its existence, rights and franchises as a corporation under the laws
of the jurisdiction of its incorporation, and will obtain and preserve its
qualification to do business as a foreign corporation in each jurisdiction in
which such qualification is or shall be necessary to protect the validity and
enforceability of this Agreement, the Certificates or any of the Mortgage Loans
and to perform its respective duties under this Agreement and (b) the Master
Servicer will keep in full effect its power and authority as a national banking
association under the laws of the jurisdiction of its organization, and will
obtain and preserve its qualification to do business in each jurisdiction in
which such qualification is or shall be necessary to protect the validity and
enforceability of this Agreement, the Certificates or any of the Mortgage Loans
and to perform its respective duties under this Agreement.

            The Depositor or the Master Servicer may be merged or consolidated
with or into any Person, or transfer all or substantially all of its assets to
any Person, in which case any Person resulting from any merger or consolidation
to which the Depositor or Master Servicer shall be a party, or any Person
succeeding to the business of the Depositor or Master Servicer, shall be the
successor of the Depositor or Master Servicer hereunder, without the execution
or filing of any paper or any further act on the part of any of the parties
hereto, anything herein to the contrary notwithstanding; provided, however,
that, (a) in the case of the Master Servicer, any such successor or resulting
Person shall have a net worth of not less than $15,000,000 and be qualified to
service mortgage loans for Fannie Mae or Freddie Mac and (b) the Master Servicer
and such successor or surviving Person shall notify the Depositor and the
Trustee of any such merger, conversion or consolidation at least two Business
Days prior to the effective date thereof (unless giving such prior notice would
be prohibited by applicable law or by a confidentiality agreement, in which case
notice shall be given by 12 noon Eastern time one Business Day after such merger
or consolidation).

            Section 6.03 Limitation on Liability of the Depositor, the Master
Servicer and Others.

            Neither the Depositor nor the Master Servicer nor any subcontractor
nor any of the directors, officers, employees or agents of any of them shall be
under any liability to the Trust Estate or the Certificateholders and all such
Persons shall be held harmless for any action taken or for refraining from the
taking of any action in good faith pursuant to this Agreement, or for errors in
judgment; provided, however, that this provision shall not protect any such
Person against any breach of warranties or representations made herein or
against any liability which would otherwise be imposed by reason of willful
misfeasance, bad faith or gross negligence in the performance of duties or by
reason of reckless disregard of obligations and duties hereunder. The Depositor,
the Master Servicer, any subcontractor, and any director, officer, employee or
agent of any of them shall be entitled to indemnification by the Trust Estate
and will be held harmless against any loss, liability or expense incurred in
connection with the performance of their duties and obligations, the exercise of
their rights or any legal action (including but not limited to, costs and
expenses of litigation, and of investigation, attorney's fees, damages,
judgments and amounts paid in settlement) under this Agreement, the Certificates
or the Mortgage Loans (except for amounts due by the Depositor in connection
with the breach of a representation or warranty covering the Mortgage Loans),
including, in the case of the Master Servicer, any indemnity amounts paid by the
Master Servicer to a Servicer pursuant to the applicable Servicing Agreement,
other than any loss, liability or expense (including without limitation,
expenses payable by the Master Servicer under Section 8.06) incurred by reason
of willful misfeasance, bad faith or gross negligence in the performance of his
or its duties hereunder or by reason of reckless disregard of his or its
obligations and duties hereunder. The Depositor, the Master Servicer and any of
the directors, officers, employees or agents of either may rely in good faith on
any document of any kind which, prima facie, is properly executed and submitted
by any Person respecting any matters arising hereunder. Neither the Depositor
nor the Master Servicer shall be under any obligation to appear in, prosecute or
defend any legal action unless such action is related to its respective duties
under this Agreement and, in its opinion, does not involve it in any expense or
liability; provided, however, that the Depositor or the Master Servicer may in
its discretion undertake any such action which it may deem necessary or
desirable with respect to this Agreement and the rights and duties of the
parties hereto and the interests of the Certificateholders hereunder if the
Certificateholders offer to the Depositor or the Master Servicer, as the case
may be, reasonable security or indemnity against the costs, expenses and
liabilities which may be incurred therein or thereby. In such event, the legal
expenses and costs of such action and any liability resulting therefrom shall be
expenses, costs and liabilities of the Trust Estate, and the Depositor or the
Master Servicer shall be entitled to be reimbursed therefor out of the
Certificate Account, and such amounts shall, on the following Distribution Date
or Distribution Dates, be allocated in reduction of distributions on the Class A
Certificates and Class B Certificates in the same manner as Realized Losses are
allocated pursuant to Section 4.02(a).

            Section 6.04 Resignation of the Master Servicer.

            The Master Servicer shall not resign from the obligations and duties
hereby imposed on it except (a) upon appointment of a successor master servicer
and receipt by the Trustee of a letter from each Rating Agency that such a
resignation and appointment will not result in a downgrading of the rating of
any of the Certificates, (b) upon determination that its duties hereunder are no
longer permissible under applicable law, or (c) pursuant to Section 6.06. Any
such determination under clause (b) permitting the resignation of the Master
Servicer shall be evidenced by an Opinion of Counsel to such effect delivered to
the Trustee. No such resignation shall become effective until the Trustee or a
successor master servicer shall have assumed the Master Servicer's
responsibilities, duties, liabilities and obligations hereunder.

            Section 6.05 Compensation to the Master Servicer.

            The Master Servicer shall be entitled to receive a monthly fee equal
to the Master Servicing Fee, as compensation for services rendered by the Master
Servicer under this Agreement. The Master Servicer also will be entitled to any
late reporting fees paid by a Servicer pursuant to its Servicing Agreement, any
investment income on funds on deposit in the Certificate Account invested in
accordance with Section 3.01(c), any investment income on funds on deposit in
the Payment Account invested in accordance with Section 4.03(a) and any
Liquidation Profits to which a Servicer is not entitled under its Servicing
Agreement.

            Section 6.06 Assignment or Delegation of Duties by Master Servicer.

            (a) The Master Servicer shall not assign or transfer any of its
rights, benefits or privileges under this Agreement to any other Person, or
delegate to or subcontract with, or authorize or appoint any other Person to
perform any of the duties, covenants or obligations to be performed by the
Master Servicer without the prior written consent of the Trustee, and any
agreement, instrument or act purporting to effect any such assignment, transfer,
delegation or appointment shall be void. Notwithstanding the foregoing, subject
to Section 6.06(b), the Master Servicer shall have the right without the prior
written consent of the Trustee (i) to assign its rights and delegate its duties
and obligations hereunder; provided, however, that (a) the purchaser or
transferee accepting such assignment or delegation is qualified to service
mortgage loans for Fannie Mae or Freddie Mac, and executes and delivers to the
Trustee an agreement, in form and substance reasonably satisfactory to the
Trustee, which contains an assumption by such purchaser or transferee of the due
and punctual performance and observance of each covenant and condition to be
performed or observed by the Master Servicer hereunder from and after the date
of such agreement; and (b) each applicable Rating Agency's rating of any
Certificates in effect immediately prior to such assignment, sale or transfer is
not reasonably likely to be qualified, downgraded or withdrawn as a result of
such assignment, sale or transfer and the Certificates are not reasonably likely
to be placed on credit review status by any such Rating Agency; and (ii) to
delegate to, subcontract with, authorize, or appoint an affiliate of the Master
Servicer to perform and carry out any duties, covenants or obligations to be
performed and carried out by the Master Servicer under this Agreement and hereby
agrees so to delegate, subcontract, authorize or appoint to an affiliate of the
Master Servicer any duties, covenants or obligations to be performed and carried
out by the Master Servicer to the extent that such duties, covenants or
obligations are to be performed in any state or states in which the Master
Servicer is not authorized to do business as a foreign corporation but in which
the affiliate is so authorized. In no case, however, shall any permitted
assignment and delegation relieve the Master Servicer of any liability to the
Trustee or the Depositor under this Agreement, incurred by it prior to the time
that the conditions contained in clause (i) above are met.

            (b) Notwithstanding anything contained herein to the contrary, to
the extent the Master Servicer engages any affiliate or third party vendor, in
connection with the performance of any of its duties under this Agreement, the
Master Servicer shall immediately notify the Depositor in writing of such
engagement (to the extent it has not already notified the Depositor pursuant to
clause (a) above); provided however, that prior to engaging any affiliate or
third party vendor in connection with the performance of any of its duties under
this Agreement, the Master Servicer shall determine (i) if such affiliates or
third party vendors would be a Servicing Function Participant and (ii) if such
affiliate or third party vendor would be a "servicer" within the meaning of Item
1101 of Regulation AB (an "Additional Master Servicer") and meets the criteria
in Item 1108(a)(2)(i), (ii) or (iii) of Regulation AB. If the Master Servicer
has determined that such affiliates or third party vendors are a Servicing
Function Participant, the Master Servicer shall cause such Servicing Function
Participant to prepare and deliver to the Master Servicer a separate assessment
and attestation report, as contemplated by Section 3.11 of this Agreement. In
addition, if the Master Servicer has determined that any such affiliate or third
party vendor would be an Additional Master Servicer and meets the criteria in
Item 1108(a)(2)(i), (ii) or (iii) of Regulation AB, the Master Servicer shall
cause such Additional Master Servicer to prepare and deliver to the Master
Servicer a separate compliance statement as contemplated by Section 3.05 of this
Agreement. In addition, if the Master Servicer determines any such affiliate or
third party vendor would be a "servicer" within the meaning of Item 1101 of
Regulation AB, the Master Servicer shall not engage such affiliate or third
party vendor unless it provides the Master Servicer and the Depositor the
information required by Section 1108(b) and 1108(c) of Regulation AB prior to
such engagement.

            (c) In the event of any assignment of rights or delegation of duties
of the Master Servicer, the Master Servicer shall report such event on Form 8-K
within four Business Days after the effective date thereof.

            Section 6.07 Indemnification of Trustee and Depositor by Master
Servicer.

            The Master Servicer shall indemnify and hold harmless the Trustee
and the Depositor and any director, officer or agent thereof against any loss,
liability or expense, including reasonable attorney's fees, arising out of, in
connection with or incurred by reason of (a) willful misfeasance, bad faith or
negligence in the performance of duties of the Master Servicer under this
Agreement or by reason of reckless disregard of its obligations and duties under
this Agreement, including, but not limited to the Master Servicer's obligation
to deliver any information, report, certification, accountants' letter or other
material required to comply with Regulation AB or (b) any material breach by the
Master Servicer of any of the representations and warranties contained in
Section 2.03(a). Any payment pursuant to this Section made by the Master
Servicer to the Trustee or the Depositor shall be from such entity's own funds,
without reimbursement therefor. The provisions of this Section 6.07 shall
survive the termination of this Agreement.

            Section 6.08 Master Servicer Errors and Omissions Policy.

            The Master Servicer shall maintain, at all times and at its own
expense, a Master Servicer Errors and Omissions Policy, which policy shall have
such terms and coverage amounts as are comparable to those of errors and
omissions policies maintained by master servicers of mortgage loans generally.

            The Master Servicer Errors and Omissions Policy shall insure the
Master Servicer, its successors and assigns, against any losses resulting from
negligence, errors or omissions on the part of officers, employees or other
persons acting on behalf of the Master Servicer in the performance of its duties
as Master Servicer pursuant to this Agreement.

            The Master Servicer shall maintain in effect the Master Servicer
Errors and Omissions Policy at all times and the Master Servicer Errors and
Omissions Policy may not be canceled, permitted to lapse or otherwise terminated
without the acquisition of comparable coverage by the Master Servicer.

<PAGE>

                                  ARTICLE VII

                                     DEFAULT

            Section 7.01 Events of Default.

            In case one or more of the following Events of Default by the Master
Servicer shall occur and be continuing, that is to say:

            (i) any failure by the Master Servicer to remit any funds to the
      Paying Agent as required by Section 4.03 continues unremedied for a period
      of three business days after either (a) receipt by the Master Servicer of
      written notice of such failure, requiring the same to be remedied, shall
      have been given to the Master Servicer by the Trustee or to the Master
      Servicer and the Trustee by the holders of Certificates evidencing in the
      aggregate not less than 25% of the aggregate Voting Interest represented
      by all Certificates or (b) solely in the case of the failure of the Master
      Servicer to remit any Periodic Advance required to be remitted pursuant to
      Section 3.03, the date upon which the Master Servicer delivered to the
      Trustee the certification required by Section 3.03(a);

            (ii) any failure on the part of the Master Servicer to observe or
      perform in any material respect any of its covenants or agreements under
      Sections 3.05, 3.11 or 3.12 hereof, subject to any cure period set forth
      in such sections;

            (iii) any failure on the part of the Master Servicer duly to observe
      or perform in any material respect any other of the covenants or
      agreements on the part of the Master Servicer in the Certificates or in
      this Agreement, which continues unremedied for a period of 60 days after
      the date on which written notice of such failure, requiring the same to be
      remedied, shall have been given to the Master Servicer by the Trustee or
      the Depositor, or to the Master Servicer and the Trustee by the holders of
      Certificates evidencing in the aggregate not less than 25% of the
      aggregate Voting Interest represented by all Certificates;

            (iv) a decree or order of a court or agency or supervisory authority
      having jurisdiction in the premises for the appointment of a trustee,
      conservator, receiver or liquidator in any bankruptcy, insolvency,
      readjustment of debt, marshaling of assets and liabilities or similar
      proceedings, or for the winding-up or liquidation of its affairs, shall
      have been entered against the Master Servicer and such decree or order
      shall have remained in force undischarged and unstayed for a period of 60
      days;

            (v) the Master Servicer shall consent to the appointment of a
      trustee, conservator, receiver or liquidator or liquidating committee in
      any bankruptcy, insolvency, readjustment of debt, marshaling of assets and
      liabilities, voluntary liquidation or similar proceedings of or relating
      to the Master Servicer, or of or relating to all or substantially all of
      its property;

            (vi) the Master Servicer shall admit in writing its inability to pay
      its debts generally as they become due, file a petition to take advantage
      of any applicable insolvency, bankruptcy or reorganization statute, make
      an assignment for the benefit of its creditors or voluntarily suspend
      payment of its obligations;

            (vii) the Master Servicer shall be dissolved, or shall dispose of
      all or substantially all of its assets; or consolidate with or merge into
      another entity or shall permit another entity to consolidate or merge into
      it, such that the resulting entity does not meet the criteria for a
      successor servicer, as specified in Section 6.02 hereof; or

            (viii) the Master Servicer and any Subservicer appointed by it
      becomes ineligible to service for both Fannie Mae and Freddie Mac, which
      ineligibility continues unremedied for a period of 90 days;

then, and in each and every such case, subject to applicable law, so long as an
Event of Default shall not have been remedied, either the Trustee or the holders
of Certificates evidencing in the aggregate not less than 66 2/3% of the
aggregate Voting Interest represented by all Certificates, by notice in writing
to the Master Servicer (and to the Trustee if given by the Certificateholders)
may terminate all of the rights and obligations of the Master Servicer under
this Agreement and in and to the Mortgage Loans, but without prejudice to any
rights which the Master Servicer may have to the aggregate Master Servicing Fees
due prior to the date of transfer of the Master Servicer's responsibilities
hereunder, reimbursement of expenses to the extent permitted by this Agreement,
Periodic Advances and other advances of its own funds. Upon receipt by the
Master Servicer of such written notice, all authority and power of the Master
Servicer under this Agreement, whether with respect to the Certificates or the
Mortgage Loans or otherwise, shall pass to and be vested in the Trustee pursuant
to and under this Section, subject to the provisions of Section 7.05; and,
without limitation, the Trustee is hereby authorized and empowered to execute
and deliver, on behalf of the Master Servicer, as attorney-in-fact or otherwise,
any and all documents and other instruments, and to do or accomplish all other
acts or things necessary or appropriate to effect the purposes of such notice of
termination, whether to complete the transfer and endorsement or assignment of
the Mortgage Loans and related documents or otherwise. The Master Servicer
agrees to cooperate with the Trustee in effecting the termination of the Master
Servicer's responsibilities and rights hereunder and shall promptly provide the
Trustee all documents and records reasonably requested by it to enable it to
assume the Master Servicer's functions hereunder and shall promptly also
transfer to the Trustee all amounts which then have been or should have been
deposited in the Certificate Account by the Master Servicer or which are
thereafter received by the Master Servicer with respect to the Mortgage Loans.

            Section 7.02 Other Remedies of Trustee.

            During the continuance of any Event of Default, so long as such
Event of Default shall not have been remedied, the Trustee, in addition to the
rights specified in Section 7.01, shall have the right, in its own name as
trustee of an express trust, to take all actions now or hereafter existing at
law, in equity or by statute to enforce its rights and remedies and to protect
the interests, and enforce the rights and remedies, of the Certificateholders
(including the institution and prosecution of all judicial, administrative and
other proceedings and the filing of proofs of claim and debt in connection
therewith). Except as otherwise expressly provided in this Agreement, no remedy
provided for by this Agreement shall be exclusive of any other remedy, and each
and every remedy shall be cumulative and in addition to any other remedy and no
delay or omission to exercise any right or remedy shall impair any such right or
remedy or shall be deemed to be a waiver of any Event of Default.

            Section 7.03 Directions by Certificateholders and Duties of Trustee
During Event of Default.

            During the continuance of any Event of Default, Holders of
Certificates evidencing in the aggregate not less than 25% of the aggregate
Voting Interest represented by all Certificates may direct the time, method and
place of conducting any proceeding for any remedy available to the Trustee, or
exercising any trust or power conferred upon the Trustee, under this Agreement;
provided, however, that the Trustee shall be under no obligation to pursue any
such remedy, or to exercise any of the rights or powers vested in it by this
agreement (including, without limitation, (i) the conducting or defending of any
administrative action or litigation hereunder or in relation hereto and (ii) the
terminating of the Master Servicer from its rights and duties as servicer
hereunder) at the request, order or direction of any of the Certificateholders,
unless such Certificateholders shall have offered to the Trustee reasonable
security or indemnity against the cost, expenses and liabilities which may be
incurred therein or thereby and, provided further, that, subject to the
provisions of Section 8.01, the Trustee shall have the right to decline to
follow any such direction if the Trustee, in accordance with an Opinion of
Counsel, determines that the action or proceeding so directed may not lawfully
be taken or if the Trustee in good faith determines that the action or
proceeding so directed would involve it in personal liability or be unjustly
prejudicial to the nonassenting Certificateholders.

            Section 7.04 Action upon Certain Failures of the Master Servicer and
upon Event of Default.

            In the event that the Trustee shall have knowledge of any failure of
the Master Servicer specified in Section 7.01(i), (ii) or (iii) which would
become an Event of Default upon the Master Servicer's failure to remedy the same
after notice, the Trustee may, but need not if the Trustee deems it not in the
Certificateholders' best interest, give notice thereof to the Master Servicer;
provided however that, without limiting any remedy as a result of such failure,
the Trustee shall be required to give notice thereof to the Master Servicer in
the case of the failure by the Master Servicer to observe or perform any of its
covenants under Sections 3.05, 3.11, 3.12, 6.02 or 6.06(b) of this Agreement.
For all purposes of this Agreement, in the absence of actual knowledge by a
Responsible Officer of the Trustee, the Trustee shall not be deemed to have
knowledge of any failure of the Master Servicer as specified in Section 7.01(i),
(ii) and (iii) or any Event of Default unless notified thereof in writing by the
Master Servicer or by a Certificateholder.

            Section 7.05 Trustee to Act; Appointment of Successor.

            When the Master Servicer receives notice of termination pursuant to
Section 7.01 or the Trustee receives the resignation of the Master Servicer
evidenced by an Opinion of Counsel pursuant to Section 6.04, the Trustee shall
be the successor in all respects to the Master Servicer in its capacity as
master servicer under this Agreement and the transactions set forth or provided
for herein and shall have the rights and powers and be subject to all the
responsibilities, duties and liabilities relating thereto placed on the Master
Servicer by the terms and provisions hereof and in its capacity as such
successor shall have the same limitation of liability herein granted to the
Master Servicer. In the event that the Trustee is succeeding to the Master
Servicer as the Master Servicer, as compensation therefor, the Trustee shall be
entitled to receive monthly such portion of the Master Servicing Fee, together
with such other master servicing compensation as is agreed to at such time by
the Trustee and the Master Servicer, but in no event more than 25% thereof until
the date of final cessation of the Master Servicer's master servicing activities
hereunder. Notwithstanding the above, the Trustee may, if it shall be unwilling
to so act, or shall, if it is unable to so act or to obtain a qualifying bid as
described below, appoint, or petition a court of competent jurisdiction to
appoint, any housing and home finance institution, bank or mortgage servicing
institution having a net worth of not less than $10,000,000 and meeting such
other standards for a successor master servicer as are set forth herein, as the
successor to the Master Servicer hereunder in the assumption of all or any part
of the responsibilities, duties or liabilities of the Master Servicer hereunder;
provided, however, that until such a successor master servicer is appointed and
has assumed the responsibilities, duties and liabilities of the Master Servicer
hereunder, the Trustee shall continue as the successor to the Master Servicer as
provided above. Upon cessation of the Master Servicer's master servicing
activities hereunder, the Trustee or any other successor master servicer shall
be entitled to compensation not exceed the compensation specified in Section
6.05 hereof, which amount shall include compensation for acting as paying agent.
If the Master Servicer and the Paying Agent are not the same party, the Master
Servicer shall pay the compensation of the Paying Agent. In the event the
Trustee is required to solicit bids as provided above, the Trustee shall
solicit, by public announcement, bids from housing and home finance
institutions, banks and mortgage servicing institutions meeting the
qualifications set forth in the preceding sentence for the purchase of the
master servicing functions. Such public announcement shall specify that the
successor master servicer shall be entitled to the full amount of the Master
Servicing Fee as compensation together with the other master servicing
compensation in the form of late reporting fees or otherwise as provided in
Section 6.05, which amount shall include compensation for acting as paying
agent. Within 30 days after any such public announcement, the Trustee shall
negotiate and effect the sale, transfer and assignment of the master servicing
rights and responsibilities hereunder to the qualified party submitting the
highest qualifying bid. The Trustee shall deduct all costs and expenses of any
public announcement and of any sale, transfer and assignment of the master
servicing rights and responsibilities hereunder from any sum received by the
Trustee from the successor to the Master Servicer in respect of such sale,
transfer and assignment. After such deductions, the remainder of such sum shall
be paid by the Trustee to the Master Servicer at the time of such sale, transfer
and assignment to the Master Servicer's successor. The Trustee and such
successor shall take such action, consistent with this Agreement, as shall be
necessary to effectuate any such succession. The Master Servicer agrees to
cooperate with the Trustee and any successor master servicer in effecting the
termination of the Master Servicer's servicing responsibilities and rights
hereunder and shall promptly provide the Trustee or such successor master
servicer, as applicable, all documents and records reasonably requested by it to
enable it to assume the Master Servicer's function hereunder and shall promptly
also transfer to the Trustee or such successor master servicer, as applicable,
all amounts which then have been or should have been deposited in the
Certificate Account by the Master Servicer or which are thereafter received by
the Master Servicer with respect to the Mortgage Loans. Neither the Trustee nor
any other successor master servicer shall be deemed to be in default hereunder
by reason of any failure to make, or any delay in making, any distribution
hereunder or any portion thereof caused by (i) the failure of the Master
Servicer to deliver, or any delay in delivering, cash, documents or records to
it, or (ii) restrictions imposed by any regulatory authority having jurisdiction
over the Master Servicer. Notwithstanding anything to the contrary contained in
Section 7.01 above or this Section 7.05, the Master Servicer shall retain all of
its rights and responsibilities hereunder, and no successor (including the
Trustee) shall succeed thereto, if the assumption thereof by such successor
would cause the rating assigned to any Certificates to be revoked, downgraded or
placed on credit review status (other than for possible upgrading) by any Rating
Agency and the retention thereof by the Master Servicer would avert such
revocation, downgrading or review.

            All costs associated with the appointment of a successor master
servicer, to the extent not deducted from any sum received by the Trustee from
the successor master servicer, shall be paid to the Person that incurred them by
the predecessor master servicer. Without limiting the predecessor master
servicer's obligation, if the predecessor master servicer fails to pay such
costs, such costs shall be reimbursed by the Trust.

            The predecessor Master Servicer and successor Master Servicer shall
notify the Depositor and Trustee of any such appointment at least two Business
Days prior to the effective date thereof and shall provide the Depositor and the
Trustee with all information required by the Depositor to comply with its
reporting obligation under Item 6.02 of Form 8-K not later than the effective
date of such appointment and the successor Master Servicer shall report such
event on Form 8-K within four business days of the occurrence of such event.

            Section 7.06 Notification to Certificateholders.

            Upon any termination of the Master Servicer or appointment of a
successor master servicer, in each case as provided herein, the Trustee shall
give prompt written notice thereof to Certificateholders at their respective
addresses appearing in the Certificate Register. The Trustee shall also, within
45 days after the occurrence of any Event of Default known to the Trustee, give
written notice thereof to Certificateholders at their respective addresses
appearing in the Certificate Register, unless such Event of Default shall have
been cured or waived within said 45 day period.

<PAGE>

                                  ARTICLE VIII

                             CONCERNING THE TRUSTEE

            Section 8.01 Duties of Trustee.

            The Trustee, prior to the occurrence of an Event of Default of which
a Responsible Officer of the Trustee shall have actual knowledge and after the
curing of all Events of Default which may have occurred, undertakes to perform
such duties and only such duties as are specifically set forth in this
Agreement. In case an Event of Default of which a Responsible Officer of the
Trustee shall have actual knowledge has occurred (which has not been cured), the
Trustee, subject to the provisions of Sections 7.01, 7.03, 7.04 and 7.05, shall
exercise such of the rights and powers vested in it by this Agreement, and use
the same degree of care and skill in its exercise as a prudent person would
exercise or use under the circumstances in the conduct of such person's own
affairs.

            The Trustee, upon receipt of all resolutions, certificates,
statements, opinions, reports, documents, orders or other instruments furnished
to the Trustee, which are specifically required to be furnished pursuant to any
provision of this Agreement, shall examine them to determine whether they are in
the form required by this Agreement; provided, however, that the Trustee shall
not be responsible for the accuracy or content of any certificate, statement,
instrument, report, notice or other document furnished by the Master Servicer or
the Servicers hereunder.

            No provision of this Agreement shall be construed to relieve the
Trustee from liability for its own negligent action, its own negligent failure
to act or its own willful misconduct; provided, however, that:

            (i) Prior to the occurrence of an Event of Default of which a
      Responsible Officer of the Trustee shall have actual knowledge and after
      the curing of all such Events of Default which may have occurred, the
      duties and obligations of the Trustee shall be determined solely by the
      express provisions of this Agreement, the Trustee shall not be liable
      except for the performance of such duties and obligations as are
      specifically set forth in this Agreement, no implied covenants or
      obligations shall be read into this Agreement against the Trustee and, in
      the absence of bad faith on the part of the Trustee, the Trustee may
      conclusively rely, as to the truth of the statements and the correctness
      of the opinions expressed therein, upon any certificates or opinions
      furnished to the Trustee, and conforming to the requirements of this
      Agreement;

            (ii) The Trustee shall not be personally liable with respect to any
      action taken, suffered or omitted to be taken by it in good faith in
      accordance with the direction of holders of Certificates which evidence in
      the aggregate not less than 25% of the Voting Interest represented by all
      Certificates relating to the time, method and place of conducting any
      proceeding for any remedy available to the Trustee, or exercising any
      trust or power conferred upon the Trustee, under this Agreement;

            (iii) The Trustee shall not be liable for any error of judgment made
      in good faith by any of its Responsible Officers, unless it shall be
      proved that the Trustee or such Responsible Officer, as the case may be,
      was negligent in ascertaining the pertinent facts; and

            (iv) The Trustee shall not be required to take notice or be deemed
      to have notice or knowledge of any default or Event of Default unless a
      Responsible Officer of the Trustee shall have received written notice or
      obtained actual knowledge thereof. In absence of such notice or actual
      knowledge, the Trustee may conclusively assume that there is no default or
      Event of Default.

            None of the provisions contained in this Agreement shall require the
Trustee to expend or risk its own funds or otherwise incur personal financial
liability in the performance of any of its duties hereunder or in the exercise
of any of its rights or powers if there is reasonable ground for believing that
repayment of such funds or adequate indemnity against such risk or liability is
not reasonably assured to it.

            Section 8.02 Certain Matters Affecting the Trustee.

            Except as otherwise provided in Section 8.01:

            (i) The Trustee may request and rely and shall be protected in
      acting or refraining from acting upon any resolution, Officer's
      Certificate, certificate of auditors or any other certificate, statement,
      instrument, opinion, report, notice, request, consent, order, appraisal,
      bond or other paper or document believed by it to be genuine and to have
      been signed or presented by the proper party or parties and the manner of
      obtaining consents and evidencing the authorization of the execution
      thereof shall be subject to such reasonable regulations as the Trustee may
      prescribe;

            (ii) The Trustee may consult with counsel, and any advice of such
      counsel or any Opinion of Counsel shall be full and complete authorization
      and protection in respect of any action taken or suffered or omitted by it
      hereunder in good faith and in accordance with such advice or Opinion of
      Counsel;

            (iii) The Trustee shall not be personally liable for any action
      taken, suffered or omitted by it in good faith and believed by it to be
      authorized or within the discretion or rights or powers conferred upon it
      by this Agreement;

            (iv) Subject to Section 7.04, the Trustee shall not be accountable,
      shall have no liability and makes no representation as to any acts or
      omissions hereunder of the Master Servicer until such time as the Trustee
      may be required to act as Master Servicer pursuant to Section 7.05 and
      thereupon only for the acts or omissions of the Trustee as successor
      Master Servicer;

            (v) The Trustee may execute any of the trusts or powers hereunder or
      perform any duties hereunder either directly or by or through agents or
      attorneys and the Trustee shall not be responsible for any misconduct or
      negligence on the part of such agent or attorney appointed by any other
      party to this Agreement, including without limitation, the appointment of
      any custodian;

            (vi) The Trustee shall be under no obligation to exercise any of the
      trusts or powers vested in it by the Agreement, conduct or defend any
      litigation hereunder or in relation hereto at the request, order or
      direction of any of the Certificateholders, pursuant to the provisions of
      this Agreement, unless such Certificateholders shall have offered to the
      Trustee security or indemnity satisfactory to the Trustee against the
      costs, expenses and liabilities which may be incurred therein or herein
      (which in the case of Certificateholders representing in the aggregate not
      less than 66-2/3% of the aggregate Voting Interests will be deemed
      satisfied by a letter agreement with respect to such costs from such
      Certificateholders);

            (vii) The right of the Trustee to perform any discretionary act
      enumerated in this Agreement shall not be construed as a duty, and the
      Trustee shall not be answerable for other than its negligence of willful
      misconduct in the performance of such act; and

            (viii) The Trustee shall not be required to give any bond or surety
      in respect of the execution of the Trust Estate created hereby or the
      powers granted hereunder.

            Section 8.03 Trustee Not Required to Make Investigation.

            Prior to the occurrence of an Event of Default of which a
Responsible Officer of the Trustee shall have actual knowledge hereunder and
after the curing of all Events of Default which may have occurred, the Trustee
shall not be bound to make any investigation into the facts or matters stated in
any resolution, certificate, statement, instrument, opinion, report, notice,
request, consent, order, appraisal, bond, Mortgage, Mortgage Note or other paper
or document (provided the same appears regular on its face), unless requested in
writing to do so by holders of Certificates evidencing in the aggregate not less
than 51% of the Voting Interest represented by all Certificates; provided,
however, that if the payment within a reasonable time to the Trustee of the
costs, expenses or liabilities likely to be incurred by it in the making of such
investigation is, in the opinion of the Trustee, not reasonably assured to the
Trustee by the security afforded to it by the terms of this Agreement, the
Trustee may require indemnity reasonably satisfactory to the Trustee against
such cost, expense or liability as a condition to so proceeding. The reasonable
expense of every such investigation shall be paid by the Master Servicer or, if
paid by the Trustee shall be repaid by the Master Servicer upon demand from the
Master Servicer's own funds.

            Section 8.04 Trustee Not Liable for Certificates or Mortgage Loans.

            The recitals contained herein and in the Certificates shall be taken
as the statements of the Depositor, and the Trustee assumes no responsibility as
to the correctness of the same. The Trustee makes no representation for the
correctness of the same. The Trustee makes no representation as to the validity
or sufficiency of this Agreement or of the Certificates or of any Mortgage Loan
or related document. Subject to Section 2.04, the Trustee shall not be
accountable for the use or application by the Depositor of any of the
Certificates or of the proceeds of such Certificates, or for the use or
application of any funds paid to the Master Servicer in respect of the Mortgage
Loans deposited in or withdrawn from the Certificate Account by the Master
Servicer or, in its capacity as trustee, for investment of any such amounts.

            Section 8.05 Trustee May Own Certificates.

            The Trustee, and any agent thereof, in its individual or any other
capacity, may become the owner or pledgee of Certificates with the same rights
it would have if it were not Trustee or such agent and may transact banking
and/or trust business or otherwise deal with the Depositor, the Master Servicer
or their Affiliates.

            Section 8.06 The Master Servicer to Pay Fees and Expenses;
Limitation on Liability.

            The Master Servicer covenants and agrees to pay to the Trustee from
time to time, from its own funds, and the Trustee shall be entitled to receive,
reasonable compensation (which shall not be limited by any provision of law in
regard to the compensation of a trustee of an express trust) for all services
rendered by it in the execution of the trusts hereby created and in the exercise
and performance of any of the powers and duties hereunder of the Trustee.

            In addition, except as otherwise agreed upon in writing by the
Master Servicer and the Trustee, the Trust shall reimburse the Trustee for all
reasonable expenses, disbursements and advances incurred or made by the Trustee
in accordance with any of the provisions of this Agreement to the extent
permitted by Treasury Regulations Section 1.860G-1(b)(3), except for (i) any
such expense, disbursement or advance arising from the Trustee's gross
negligence, bad faith or willful misconduct and (ii) any routine ongoing
expenses incurred by the Trustee in the ordinary course of its duties as Trustee
hereunder or for any other expenses.

            The Trustee and any director, officer, employee or agent of the
Trustee shall be entitled to indemnification by the Trust Estate and held
harmless against any loss, liability or expense (including reasonable attorney's
fees) (a) incurred in connection with any claim or legal action relating to (i)
this Agreement, (ii) the Certificates, or (iii) the performance of any of the
Trustee's duties under this Agreement, unless the loss, liability or expense was
incurred by reason of willful misfeasance, bad faith or gross negligence in the
performance of any of the Trustee's duties under this Agreement and (b)
resulting from any tax or information return which was prepared by, or should
have been prepared by, the applicable Servicer or Master Servicer.

            The obligations of the Trust Estate under this Section 8.06 shall
survive the resignation and removal of the Trustee and payment of the
Certificates.

            Section 8.07 Eligibility Requirements.

            The Trustee hereunder shall at all times (i) be a corporation or
association having its principal office in a state and city acceptable to the
Depositor, organized and doing business under the laws of such state or the
United States of America, authorized under such laws to exercise corporate trust
powers, having a combined capital and surplus of at least $50,000,000, or shall
be a member of a bank holding system, the aggregate combined capital and surplus
of which is at least $50,000,000, provided that its separate capital and surplus
shall at all times be at least the amount specified in Section 310(a)(2) of the
Trust Indenture Act of 1939, (ii) be subject to supervision or examination by
federal or state authority and (iii) have a credit rating or be otherwise
acceptable to the Rating Agencies such that none of the Rating Agencies would
reduce their respective then current ratings of the Certificates (or have
provided such security from time to time as is sufficient to avoid such
reduction) as evidenced in writing by each Rating Agency. If such corporation or
association publishes reports of condition at least annually, pursuant to law or
to the requirements of the aforesaid supervising or examining authority, then
for the purposes of this Section the combined capital and surplus of such
corporation or association shall be deemed to be its combined capital and
surplus as set forth in its most recent report of condition so published. In
case at any time the Trustee shall cease to be eligible in accordance with the
provisions of this Section, the Trustee shall resign immediately in the manner
and with the effect specified in Section 8.08.

            Section 8.08 Resignation and Removal.

            The Trustee may at any time resign and be discharged from the trust
hereby created by giving written notice of resignation to the Master Servicer,
such resignation to be effective upon the appointment of a successor trustee.
Upon receiving such notice of resignation, the Master Servicer shall promptly
appoint a successor trustee by written instrument, in duplicate, one copy of
which instrument shall be delivered to the resigning entity and one copy to its
successor. If no successor trustee shall have been appointed and have accepted
appointment within 30 days after the giving of such notice of resignation, the
resigning Trustee may petition any court of competent jurisdiction for the
appointment of a successor trustee.

            If at any time the Trustee shall cease to be eligible in accordance
with the provisions of Section 8.07 and shall fail to resign after written
request for its resignation by the Master Servicer, or if at any time the
Trustee shall become incapable of acting, or an order for relief shall have been
entered in any bankruptcy or insolvency proceeding with respect to such entity,
or a receiver of such entity or of its property shall be appointed, or any
public officer shall take charge or control of the Trustee or of the property or
affairs of the Trustee for the purpose of rehabilitation, conversion or
liquidation, or the Master Servicer shall deem it necessary in order to change
the situs of the Trust Estate for state tax reasons, then the Master Servicer
shall remove the Trustee and appoint a successor trustee by written instrument,
in duplicate, one copy of which instrument shall be delivered to the Trustee so
removed and one copy to the successor trustee.

            In addition, if (a) the Trustee fails to comply with its obligations
to deliver any assessment of servicing compliance or registered public
accounting firm attestation reports required pursuant to Section 3.11 or (b) any
Servicing Function Participant engaged by the Trustee fails to comply with its
obligations to deliver any assessment of servicing compliance or registered
public accounting firm attestation reports, the Master Servicer, may, after
consultation with the Depositor, remove the Trustee and appoint a successor
trustee by written instrument, in duplicate, one copy of which instrument shall
be delivered to the Trustee so removed and one copy to the successor trustee.

            The Holders of Certificates evidencing in the aggregate not less
than 51% of the Voting Interests represented by all Certificates (except that
any Certificate registered in the name of the Depositor, the Master Servicer or
any affiliate thereof will not be taken into account in determining whether the
requisite Voting Interests has been obtained) may at any time remove the Trustee
and appoint a successor by written instrument or instruments, in triplicate,
signed by such holders or their attorneys-in-fact duly authorized, one complete
set of which instruments shall be delivered to the Master Servicer, one complete
set of which shall be delivered to the entity or entities so removed and one
complete set of which shall be delivered to the successor so appointed.

            Any resignation or removal of the Trustee and appointment of a
successor pursuant to any of the provisions of this Section shall become
effective upon acceptance of appointment by the successor as provided in Section
8.09.

            Section 8.09 Successor.

            Any successor trustee appointed as provided in Section 8.08 shall
execute, acknowledge and deliver to the Master Servicer and to its predecessor
trustee an instrument accepting such appointment hereunder, and thereupon the
resignation or removal of the predecessor trustee shall become effective, and
such successor, without any further act, deed or reconveyance, shall become
fully vested with all the rights, powers, duties and obligations of its
predecessor hereunder, with like effect as if originally named as trustee
herein. The predecessor trustee shall deliver to its successor all documents and
statements held by it hereunder, and the Depositor, the Master Servicer and the
predecessor entity shall execute and deliver such instruments and do such other
things as may reasonably be required for more fully and certainly vesting and
confirming in the successor trustee all such rights, powers, duties and
obligations.

            If the predecessor trustee has resigned, or has been removed for
cause, all costs associated with the appointment of a successor trustee shall be
paid to the Person that incurred them by the predecessor trustee. Without
limiting the predecessor trustee's obligation, if the predecessor trustee fails
to pay such costs, such costs shall be reimbursed by the Trust; provided
however, that if the predecessor trustee has been terminated without cause
pursuant to Section 8.08, all reasonable expenses incurred in complying with
this Section 8.09 shall be reimbursed by the Trust to the Person that incurred
them.

            No successor shall accept appointment as provided in this Section
unless at the time of such acceptance such successor shall be eligible under the
provisions of Section 8.07.

            Upon acceptance of appointment by a successor as provided in this
Section, the successor trustee shall mail notice of the succession of such
trustee hereunder to all Holders of Certificates at their addresses as shown in
the Certificate Register.

            Section 8.10 Merger or Consolidation.

            Any Person into which the Trustee may be merged or converted or with
which it may be consolidated, to which it may sell or transfer its corporate
trust business and assets as a whole or substantially as a whole or any Person
resulting from any merger, sale, transfer, conversion or consolidation to which
the Trustee shall be a party, or any Person succeeding to the business of such
entity, shall be the successor of the Trustee hereunder; provided, however, that
(i) such Person shall be eligible under the provisions of Section 8.07, without
the execution or filing of any paper or any further act on the part of any of
the parties hereto, anything herein to the contrary notwithstanding and (ii) the
Trustee and such successor or surviving Person shall notify the Depositor and
the Master Servicer of any such merger, conversion or consolidation at least two
Business Days prior to the effective date thereof and shall provide the
Depositor and the Master Servicer with all information required by the Depositor
to comply with its reporting obligations under Item 6.02 of Form 8-K not later
than the effective date of such merger, conversion or consolidation and the
Master Servicer shall report such event on Form 8-K within four business days of
the occurrence of such event.

            Section 8.11 Authenticating Agent.

            The Trustee may appoint an Authenticating Agent, which shall be
authorized to act on behalf of the Trustee in authenticating Certificates.
Wherever reference is made in this Agreement to the authentication of
Certificates by the Trustee or the Trustee's countersignature, such reference
shall be deemed to include authentication on behalf of the Trustee by the
Authenticating Agent and a certificate of authentication executed on behalf of
the Trustee by the Authenticating Agent. The Authenticating Agent must be
acceptable to the Depositor and the Master Servicer and must be a corporation
organized and doing business under the laws of the United States of America or
of any state, having a principal office and place of business in a state and
city acceptable to the Depositor and the Master Servicer, having a combined
capital and surplus of at least $15,000,000, authorized under such laws to do a
trust business and subject to supervision or examination by federal or state
authorities.

            Any corporation into which the Authenticating Agent may be merged or
converted or with which it may be consolidated, or any corporation resulting
from any merger, conversion or consolidation to which the Authenticating Agent
shall be a party, or any corporation succeeding to the corporate agency business
of the Authenticating Agent, shall be the Authenticating Agent without the
execution or filing of any paper or any further act on the part of the Trustee
or the Authenticating Agent.

            The Authenticating Agent may at any time resign by giving at least
30 days' advance written notice of resignation to the Trustee, the Depositor and
the Master Servicer. Except with respect to Wells Fargo Bank, for so long as
Wells Fargo Bank is acting as the Master Servicer, the Trustee may at any time
terminate the agency of the Authenticating Agent by giving written notice
thereof to the Authenticating Agent, the Depositor and the Master Servicer. Upon
receiving a notice of resignation or upon such a termination, or in case at any
time the Authenticating Agent shall cease to be eligible in accordance with the
provisions of this Section 8.11, the Trustee promptly shall appoint a successor
Authenticating Agent, which shall be acceptable to the Master Servicer, and
shall give written notice of such appointment to the Depositor, and shall mail
notice of such appointment to all Certificateholders. Any successor
Authenticating Agent upon acceptance of its appointment hereunder shall become
vested with all the rights, powers, duties and responsibilities of its
predecessor hereunder, with like effect as if originally named as Authenticating
Agent herein. No successor Authenticating Agent shall be appointed unless
eligible under the provisions of this Section 8.11.

            The Authenticating Agent shall have no responsibility or liability
for any action taken by it as such at the direction of the Trustee. Any
reasonable compensation paid to the Authenticating Agent shall be payable by the
Master Servicer.

            Section 8.12 Separate Trustees and Co-Trustees.

            The Trustee shall have the power from time to time to appoint one or
more persons or corporations to act either as co-trustees jointly with the
Trustee, or as separate trustees, for the purpose of holding title to,
foreclosing or otherwise taking action with respect to any Mortgage Loan outside
the state where the Trustee has its principal place of business, where such
separate trustee or co-trustee is necessary or advisable (or the Trustee is
advised by the Master Servicer that such separate trustee or co-trustee is
necessary or advisable) under the laws of any state in which a Mortgaged
Property is located or for the purpose of otherwise conforming to any legal
requirement, restriction or condition in any state in which a Mortgaged Property
is located or in any state in which any portion of the Trust Estate is located.
The Master Servicer shall advise the Trustee when, in its good faith opinion, a
separate trustee or co-trustee is necessary or advisable as aforesaid. The
separate trustees or co-trustees so appointed shall be trustees for the benefit
of all of the Certificateholders and shall have such powers, rights and remedies
as shall be specified in the instrument of appointment; provided, however, that
no such appointment shall, or shall be deemed to, constitute the appointee an
agent of the Trustee. The Depositor and the Master Servicer shall join in any
such appointment, but such joining shall not be necessary for the effectiveness
of such appointment.

            Every separate trustee and co-trustee shall, to the extent permitted
by law, be appointed and act subject to the following provisions and conditions:

            (i) all powers, duties, obligations and rights conferred upon the
      Trustee, in respect of the receipt, custody and payment of moneys shall be
      exercised solely by the Trustee;

            (ii) all other rights, powers, duties and obligations conferred or
      imposed upon the Trustee shall be conferred or imposed upon and exercised
      or performed by the Trustee and such separate trustee or co-trustee
      jointly, except to the extent that under any law of any jurisdiction in
      which any particular act or acts are to be performed (whether as Trustee
      hereunder or as successor to the Master Servicer hereunder) the Trustee
      shall be incompetent or unqualified to perform such act or acts, in which
      event such rights, powers, duties and obligations (including the holding
      of title to the Trust Estate or any portion thereof in any such
      jurisdiction) shall be exercised and performed by such separate trustee or
      co-trustee;

            (iii) no separate trustee or co-trustee hereunder shall be
      personally liable by reason of any act or omission of any other separate
      trustee or co-trustee hereunder; and

            (iv) the Trustee may at any time accept the resignation of or remove
      any separate trustee or co-trustee so appointed by it, if such resignation
      or removal does not violate the other terms of this Agreement.

            Any notice, request or other writing given to the Trustee shall be
deemed to have been given to each of the then separate trustees and co-trustees,
as effectively as if given to each of them. Every instrument appointing any
separate trustee, co-trustee, or custodian shall refer to this Agreement and the
conditions of this Article. Each separate trustee and co-trustee, upon its
acceptance of the trusts conferred, shall be vested with the estates or property
specified in its instrument of appointment, either jointly with the Trustee, or
separately, as may be provided therein, subject to all the provisions of this
Agreement, specifically including every provision of this Agreement relating to
the conduct of, affecting the liability of, or affording protection to, the
Trustee. Every such instrument shall be furnished to the Trustee.

            Any separate trustee, co-trustee, or custodian may, at any time,
constitute the Trustee, its agent or attorney-in-fact, with full power and
authority, to the extent not prohibited by law, to do any lawful act under or in
respect of this Agreement on its behalf and in its name. If any separate trustee
or co-trustee shall die, become incapable of acting, resign or be removed, all
of its estates, properties, rights, remedies and trusts shall vest in and be
exercised by the Trustee to the extent permitted by law, without the appointment
of a new or successor trustee.

            No separate trustee or co-trustee hereunder shall be required to
meet the terms of eligibility as a successor trustee under Section 8.07
hereunder and no notice to Certificateholders of the appointment thereof shall
be required under Section 8.09 hereof.

            The Trustee agrees to instruct its co-trustees, if any, to the
extent necessary to fulfill such entity's obligations hereunder.


            The fees of any co-trustee whose appointment is necessary or
advisable for (i) conforming to any legal requirement, restriction or condition
in any state in which any Mortgaged Property or any portion of the Trust Estate
is located, will be paid by the Master Servicer, without reimbursement from the
Trust and (ii) any reason other than contemplated by clause (i), will be paid by
the Trustee, without reimbursement from the Trust. Expenses will be reimbursable
to the co-trustees to the extent, and in accordance with the standards,
specified in Section 8.06 hereof.

            Section 8.13 Tax Matters; Compliance with REMIC Provisions.

            (a) Each of the Trustee and the Master Servicer covenants and agrees
that it shall perform its duties hereunder in a manner consistent with the REMIC
Provisions and shall not knowingly take any action or fail to take any other
action that would (i) affect the determination of the Trust Estate's status as
two separate REMICs; or (ii) cause the imposition of any federal, state or local
income, prohibited transaction, contribution or other tax on any of the
Upper-Tier REMIC, the Lower-Tier REMIC or the Trust Estate. The Master Servicer,
or, in the case of any tax return or other action required by law to be
performed directly by the Trustee, the Trustee, shall (i) prepare or cause to be
prepared, timely cause to be signed by the Trustee and file or cause to be filed
annual federal and applicable state and local income tax returns for each of the
Upper-Tier REMIC and the Lower-Tier REMIC using a calendar year as the taxable
year and the accrual method of accounting; (ii) in the first such federal tax
return, make, or cause to be made, elections satisfying the requirements of the
REMIC Provisions, on behalf of the Trust Estate, to treat each of the Upper-Tier
REMIC and the Lower-Tier REMIC as a REMIC; (iii) prepare, execute and forward,
or cause to be prepared, executed and forwarded, to the Certificateholders all
information reports or tax returns required with respect to the Trust Estate, as
and when required to be provided to the Certificateholders, and to the Internal
Revenue Service and any other relevant governmental taxing authority in
accordance with the REMIC Provisions and any other applicable federal, state or
local laws, including without limitation information reports relating to
"original issue discount" and "market discount" as defined in the Code based
upon the issue prices, prepayment assumption and cash flows provided by the
Depositor to the Master Servicer and calculated on a monthly basis by using the
issue prices of the Certificates; (iv) make available information necessary for
the application of any tax imposed on transferors of residual interests to
"disqualified organizations" (as defined in the REMIC Provisions); (v) file Form
8811 and apply for an Employee Identification Number with a Form SS-4 or any
other permissible method and respond to inquiries by Certificateholders or their
nominees concerning information returns, reports or tax returns; (vi) maintain
(or cause to be maintained by the Servicers) such records relating to the
Upper-Tier REMIC and the Lower-Tier REMIC, including but not limited to the
income, expenses, individual Mortgage Loans (including REO Mortgage Loans),
other assets and liabilities of each REMIC, and the fair market value and
adjusted basis of the property of each REMIC determined at such intervals as may
be required by the Code, as may be necessary to prepare the foregoing returns or
information reports; (vii) exercise reasonable care not to allow the creation of
any "interests" in either of the Upper-Tier REMIC or the Lower-Tier REMIC within
the meaning of Code Section 860D(a)(2) other than the interests in the
Upper-Tier REMIC represented by the Class A-1, Class A-2, Class A-3, Class A-4,
Class A-5, Class A-6, Class A-7, Class A-8, Class A-9, Class A-10, Class A-11,
Class A-12, Class A-13, Class A-14, Class A-15, Class A-16, Class A-17, Class
A-18, Class A-19, Class A-20, Class A-21, Class A-PO, Class B-1, Class B-2,
Class B-3, Class B-4, Class B-5 and Class B-6 Certificates and the Class A-R
Interest, and the interests in the Lower-Tier REMIC represented by the Class
A-L1 Interest, Class A-L5 Interest, Class A-L7 Interest, Class A-L16 Interest,
Class A-LPO Interest, Class A-LUR Interest, Class B-L1 Interest, Class B-L2
Interest, Class B-L3 Interest, Class B-L4 Interest, Class B-L5 Interest and
Class B-L6 Interest and the Class A-LR Interest; (viii) exercise reasonable care
not to allow the occurrence of any "prohibited transactions" within the meaning
of Code Section 860F(a), unless the Master Servicer shall have provided an
Opinion of Counsel to the Trustee that such occurrence would not (a) result in a
taxable gain, (b) otherwise subject any of the Upper-Tier REMIC, the Lower-Tier
REMIC or the Trust Estate to tax or (c) cause the Trust Estate to fail to
qualify as two separate REMICs; (ix) exercise reasonable care not to allow
either of the Upper-Tier REMIC or the Lower-Tier REMIC to receive income from
the performance of services or from assets not permitted under the REMIC
Provisions to be held by a REMIC; and (x) pay (on behalf of the Upper-Tier REMIC
or the Lower-Tier REMIC) the amount of any federal income tax, including,
without limitation, prohibited transaction taxes, taxes on net income from
foreclosure property, and taxes on certain contributions to a REMIC after the
Startup Day, imposed on the Upper-Tier REMIC or the Lower-Tier REMIC, as the
case may be, when and as the same shall be due and payable (but such obligation
shall not prevent the Master Servicer or any other appropriate Person from
contesting any such tax in appropriate proceedings and shall not prevent the
Master Servicer from withholding or depositing payment of such tax, if permitted
by law, pending the outcome of such proceedings). The Master Servicer shall be
entitled to be reimbursed pursuant to Section 3.02 for any taxes paid by it
pursuant to clause (x) of the preceding sentence, except to the extent that such
taxes are imposed as a result of the bad faith, willful misfeasance or gross
negligence of the Master Servicer in the performance of its obligations
hereunder.

            In order to enable the Master Servicer or the Trustee, as the case
may be, to perform its duties as set forth above, the Depositor shall provide,
or cause to be provided, to the Master Servicer within ten days after the
Closing Date all information or data that the Master Servicer determines to be
relevant for tax purposes to the valuations and offering prices of the
Certificates, including, without limitation, the price, yield, prepayment
assumption and projected cash flows of each Class of Certificates and the
Mortgage Loans in the aggregate. Thereafter, the Depositor shall provide to the
Master Servicer or the Trustee, as the case may be, promptly upon request
therefor, any such additional information or data that the Master Servicer or
the Trustee, as the case may be, may from time to time request in order to
enable the Master Servicer to perform its duties as set forth above. The
Depositor hereby indemnifies the Master Servicer or the Trustee, as the case may
be, for any losses, liabilities, damages, claims or expenses of the Master
Servicer or the Trustee arising from any errors or miscalculations by the Master
Servicer or the Trustee pursuant to this Section that result from any failure of
the Depositor to provide, or to cause to be provided, accurate information or
data to the Master Servicer or the Trustee, as the case may be, on a timely
basis. The Master Servicer hereby indemnifies the Depositor and the Trustee for
any losses, liabilities, damages, claims or expenses of the Depositor or the
Trustee arising from the Master Servicer's willful misfeasance, bad faith or
gross negligence in preparing any of the federal, state and local tax returns of
either REMIC as described above. In the event that the Trustee prepares any of
the federal, state and local tax returns of either REMIC as described above, the
Trustee hereby indemnifies the Depositor and the Master Servicer for any losses,
liabilities, damages, claims or expenses of the Depositor or the Master Servicer
arising from the Trustee's willful misfeasance, bad faith or negligence in
connection with such preparation.

            (b) Notwithstanding anything in this Agreement to the contrary, each
of the Master Servicer and the Trustee shall pay from its own funds, without any
right of reimbursement therefor, the amount of any costs, liabilities and
expenses incurred by the Trust Estate (including, without limitation, any and
all federal, state or local taxes, including taxes imposed on "prohibited
transactions" within the meaning of the REMIC Provisions) if and to the extent
that such costs, liabilities and expenses arise from a failure of the Master
Servicer or the Trustee, respectively, to perform its obligations under this
Section 8.13.

            The Holder of the Residual Certificate is hereby designated as the
"tax matters person" for the Upper-Tier REMIC and the Lower-Tier REMIC within
the meaning of Treasury Regulations Section 1.860F-4(d). The "tax matters
person" shall have the same duties with respect to the applicable REMIC as those
of a "tax matters partner" under Subchapter C of Chapter 63 of Subtitle F of the
Code. By its acceptance of the Residual Certificate, such Holder irrevocably
appoints the Master Servicer (and the Master Servicer hereby agrees to act) as
agent to perform all of the duties of the "tax matters person."

            (c) For federal tax return and information reporting, the right of
the Holders of the Class A-5 Certificates to receive payments under the Yield
Maintenance Agreement shall be assigned the value specified in the certification
by Greenwich Capital Markets, Inc. in the form attached as Exhibit X hereto.

            Section 8.14 Monthly Advances.

            In the event that Wells Fargo Bank in its capacity as Servicer fails
to make a Periodic Advance required to be made pursuant to the Wells Fargo Bank
Servicing Agreement on or before the Distribution Date, the Trustee shall make a
Periodic Advance as required by Section 3.03 hereof; provided, however, the
Trustee shall not be required to make such Periodic Advances if prohibited by
law or if it determines that such Periodic Advance would be a Nonrecoverable
Advance. With respect to those Periodic Advances which should have been made by
Wells Fargo Bank, the Trustee shall be entitled, pursuant to Section 3.02(a)(i),
(ii) or (v) hereof, to be reimbursed from the Certificate Account for Periodic
Advances and Nonrecoverable Advances made by it.

            Section 8.15 Indemnification of the Master Servicer and Depositor by
the Trustee.

            The Trustee shall indemnify and hold harmless the Master Servicer
and the Depositor and any director, officer or agent thereof against any loss,
liability or expense, including reasonable attorney's fees, arising out of, in
connection with or incurred by reason of willful misfeasance, bad faith or
negligence in the performance of duties of the Trustee or by reason of reckless
disregard of its obligation to deliver any information, report, certification,
accountants' letter or other material required to comply with Regulation AB. Any
payment pursuant to this Section made by the Trustee to the Master Servicer or
the Depositor shall be from such entity's own funds, without reimbursement
therefor. The provisions of this Section 8.15 shall survive the termination of
this Agreement.

            Notwithstanding anything in this Agreement to the contrary, in no
event shall the Trustee be liable for any special, indirect or consequential
loss or damage of any kind whatsoever (including but not limited to lost
profits) resulting from the Trustee's nonperformance of its duties or
obligations to deliver any information, report, certification, accountants'
letter or other material required to comply with Regulation AB, even if the
Trustee has been advised of the likelihood of such loss or damage and regardless
of the form of action.

            Section 8.16 Trustee Errors and Omissions Policy.

            The Trustee shall maintain, at all times and at its own expense, a
Trustee Errors and Omissions Policy, which policy shall have such terms and
coverage amounts as are comparable to those of errors and omissions policies
maintained by trustees generally.

            The Trustee Errors and Omissions Policy shall insure the Trustee,
its successors and assigns, against any losses resulting from negligence, errors
or omissions on the part of officers, employees or other persons acting on
behalf of the Trustee in the performance of its duties as Trustee pursuant to
this Agreement.

            The Trustee shall maintain in effect the Trustee Errors and
Omissions Policy at all times and the Trustee Errors and Omissions Policy may
not be canceled, permitted to lapse or otherwise terminated without thirty
Business Days' prior written notice by registered mail to the Master Servicer
and the Depositor.

<PAGE>

                                   ARTICLE IX

                                   TERMINATION

            Section 9.01 Termination upon Purchase by the Depositor or
Liquidation of All Mortgage Loans.

            Subject to Section 9.02, the respective obligations and
responsibilities of the parties to this Agreement created hereby (other than the
obligation of the Paying Agent to make certain payments after the Final
Distribution Date to Certificateholders and the obligation of the Master
Servicer to send certain notices as hereinafter set forth and the tax reporting
obligations under Sections 4.05 and 8.13 hereof) shall terminate upon the last
action required to be taken by the Paying Agent on the Final Distribution Date
pursuant to this Article IX following the earlier of (i) the purchase by the
Depositor of all Mortgage Loans and all property acquired in respect of any
Mortgage Loan remaining in the Trust Estate at a price equal to the sum of (x)
100% of the unpaid principal balance of each Mortgage Loan (other than any REO
Mortgage Loan) as of the Final Distribution Date, (y) the fair market value of
the Mortgaged Property related to any REO Mortgage Loan, plus with respect to
clauses (x) and (y) any accrued and unpaid interest through the last day of the
month preceding the month of such purchase at the applicable Mortgage Interest
Rate less any Fixed Retained Yield on each Mortgage Loan (including any REO
Mortgage Loan) and (z) any Reimbursement Amount owed to the Trust pursuant to
Section 2.03 and (ii) the final payment or other liquidation (or any advance
with respect thereto) of the last Mortgage Loan remaining in the Trust Estate
(including for this purpose the discharge of any Mortgagor under a defaulted
Mortgage Loan on which a Servicer is not obligated to foreclose due to
environmental impairment) or the disposition of all property acquired upon
foreclosure or deed in lieu of foreclosure of any Mortgage Loan; provided,
however, that in no event shall the trust created hereby continue beyond the
expiration of 21 years from the death of the last survivor of the descendants of
Joseph P. Kennedy, the late ambassador of the United States to the Court of St.
James, living on the date hereof.

            The right of the Depositor to purchase all the assets of the Trust
Estate pursuant to clause (i) of the preceding paragraph is subject to Section
9.02 and conditioned upon (A) the Pool Scheduled Principal Balance of the
Mortgage Loans as of the Final Distribution Date being less than the amount set
forth in Section 11.21 and (B) the sum of clause (i)(x) and (y) of the preceding
paragraph being less than or equal to the aggregate fair market value of the
Mortgage Loans (other than any REO Mortgage Loans) and the Mortgaged Properties
related to the REO Mortgage Loans; provided, however, that this clause (B) shall
not apply to any purchase by the Depositor if, at the time of the purchase, the
Depositor is no longer subject to regulation by the Office of the Comptroller of
the Currency, the FDIC, the Federal Reserve or the Office of Thrift Supervision.
Fair market value for purposes of this paragraph and the preceding paragraph
will be determined by the Master Servicer as of the close of business on the
third Business Day next preceding the date upon which notice of any termination
is furnished to Certificateholders pursuant to the third paragraph of this
Section 9.01. In the case of any purchase by the Depositor pursuant to said
clause (i) of the preceding paragraph, the Depositor shall give the Trustee, the
Paying Agent and Master Servicer notice of its intent to purchase the assets of
the Trust by the fifth day of the month of the Final Distribution Date or such
later date as shall be acceptable to the Trustee and Master Servicer. The
Depositor or Master Servicer shall in such case provide to the Trustee the
confirmation of deposit of the purchase price required by Section 3.04 and the
Trustee or the Custodian shall, promptly following payment of the purchase price
and upon receipt from the Master Servicer of a Request for Release, release to
the Depositor the Owner Mortgage Loan Files and Retained Mortgage Loan Files, if
applicable, pertaining to the Mortgage Loans being purchased.

            Notice of any termination, specifying the Final Distribution Date
(which shall be a date that would otherwise be a Distribution Date) upon which
the Certificateholders may surrender their Certificates to the Paying Agent for
payment of the final distribution and cancellation, shall be given promptly by
the Paying Agent by letter to Certificateholders and the Trustee mailed not
earlier than the 15th day of the month preceding the month of such final
distribution and not later than the twentieth day of the month of such final
distribution specifying (A) the Final Distribution Date upon which final payment
of the Certificates will be made upon presentation and surrender of Certificates
at the Corporate Trust Office of the Paying Agent therein designated, (B) the
amount of any such final payment and (C) that the Record Date otherwise
applicable to such Distribution Date is not applicable, payments being made
(except in the case of any Class A Certificate surrendered on a prior
Distribution Date) pursuant to Section 4.01 only upon presentation and surrender
of the Certificates at the Corporate Trust Office of the Paying Agent therein
specified. If the Depositor is exercising its right to purchase, the Depositor
shall deposit in the Certificate Account on or before the Final Distribution
Date in immediately available funds an amount equal to the purchase price for
the assets of the Trust Estate computed as above provided. Failure to give
notice of termination as described herein shall not entitle a Certificateholder
to any interest beyond the interest payable on the Final Distribution Date.

            Upon presentation and surrender of the Certificates, the Paying
Agent shall distribute to Certificateholders on the Final Distribution Date in
proportion to their respective Percentage Interests an amount equal to (i) as to
the Classes of Class A Certificates, the respective Principal Balance together
with any related Class A Unpaid Interest Shortfall and one month's interest in
an amount equal to the respective Interest Accrual Amount, (ii) as to the
Classes of Class B Certificates, the respective Principal Balance together with
any related Class B Unpaid Interest Shortfall and one month's interest in an
amount equal to the respective Interest Accrual Amount and (iii) as to the Class
A-R Certificate, the amounts, if any, which remain on deposit in the Upper-Tier
Certificate Account and the Certificate Account, respectively (other than
amounts retained to meet claims), after application pursuant to clauses (i) and
(ii) above and payment to the Master Servicer of any amounts it is entitled as
reimbursement or otherwise hereunder. Such amount shall be distributed in
respect of interest and principal in respect of the Uncertificated Lower-Tier
Interests in the manner specified in Section 4.01(a). Notwithstanding the
foregoing, if the price paid pursuant to clause (i) of the first paragraph of
this Section 9.01, after reimbursement to the Servicers, the Master Servicer and
the Trustee of any Periodic Advances, is insufficient to pay in full the amounts
set forth in clauses (i) and (ii) of this paragraph, then any shortfall in the
amount available for distribution to Certificateholders shall be allocated in
reduction of the amounts otherwise distributable on the Final Distribution Date
in the same manner as Realized Losses are allocated pursuant to Sections 4.02(a)
and (e) hereof. Such distribution on the Final Distribution Date shall be in
lieu of the distribution otherwise required to be made on such Distribution Date
in respect of each Class of Certificates.

            In the event that all of the Certificateholders shall not surrender
their Certificates for final payment and cancellation within three months
following the Final Distribution Date, the Paying Agent shall on such date cause
all funds, if any, in the Payment Account not distributed in final distribution
to Certificateholders to be withdrawn therefrom and credited to the remaining
Certificateholders by depositing such funds in a separate escrow account for the
benefit of such Certificateholders. The Paying Agent shall give a second written
notice to the remaining Certificateholders to surrender their Certificates for
cancellation and receive the final distribution with respect thereto. If within
three months after the second notice all the Certificates shall not have been
surrendered for cancellation, the Paying Agent may take appropriate steps, or
may appoint an agent to take appropriate steps, to contact the remaining
Certificateholders concerning surrender of their Certificates, and the cost
thereof shall be paid out of the funds on deposit in such escrow account.

            Section 9.02 Additional Termination Requirements.

            In the event of a termination of the Trust Estate upon the exercise
by the Depositor of its purchase option as provided in Section 9.01, the Trust
Estate shall be terminated in accordance with the following additional
requirements, unless the Trustee and the Master Servicer have received an
Opinion of Counsel to the effect that any other manner of termination (i) will
constitute a "qualified liquidation" of the Trust Estate within the meaning of
Code Section 860F(a)(4)(A) and (ii) will not subject either of the Upper-Tier
REMIC or the Lower-Tier REMIC to federal tax or cause the Trust Estate to fail
to qualify as two separate REMICs at any time that any Certificates are
outstanding:

            (i) The notice given by the Paying Agent under Section 9.01 shall
      provide that such notice constitutes the adoption of a plan of complete
      liquidation of the Upper-Tier REMIC and the Lower-Tier REMIC as of the
      date of such notice (or, if earlier, the date on which the first such
      notice is mailed to Certificateholders). The Master Servicer shall also
      specify such date in a statement attached to the final tax returns of the
      Upper-Tier REMIC and the Lower-Tier REMIC; and

            (ii) At or after the time of adoption of such a plan of complete
      liquidation and at or prior to the Final Distribution Date, the Trustee,
      shall sell all of the assets of the Trust Estate to the Depositor for cash
      at the purchase price specified in Section 9.01 and the Paying Agent shall
      distribute such cash within 90 days of such adoption in the manner
      specified in Section 9.01.

<PAGE>

                                   ARTICLE X

                            MISCELLANEOUS PROVISIONS

            Section 10.01 Amendment.

            (a) This Agreement or the Custodial Agreement may be amended from
time to time by the Depositor, the Master Servicer and the Trustee without the
consent of any of the Certificateholders, (i) to cure any ambiguity or mistake,
(ii) to correct or supplement any provisions herein or therein which may be
inconsistent with any other provisions herein or therein or in the related
Prospectus, (iii) to modify, eliminate or add to any of its provisions to such
extent as shall be necessary to maintain the qualification of the Trust Estate
as two separate REMICs at all times that any Certificates are outstanding or to
avoid or minimize the risk of the imposition of any federal tax on the Trust
Estate, the Upper-Tier REMIC or the Lower-Tier REMIC pursuant to the Code that
would be a claim against the Trust Estate, provided that (a) the Trustee has
received an Opinion of Counsel to the effect that such action is necessary or
desirable to maintain such qualification or to avoid or minimize the risk of the
imposition of any such tax and (b) such action shall not, as evidenced by such
Opinion of Counsel, adversely affect in any material respect the interests of
any Certificateholder, (iv) to conform the obligations of the parties under this
Agreement, or to add obligations of the parties to this Agreement, if necessary,
to comply with the requirements of Regulation AB, (v) to change the timing
and/or nature of deposits into the Upper-Tier Certificate Account and the
Certificate Account provided that such change shall not, as evidenced by an
Opinion of Counsel, adversely affect in any material respect the interests of
any Certificateholder, (vi) to modify, eliminate or add to the provisions of
Section 5.02 or any other provisions hereof restricting transfer of the
Certificates, provided that the Depositor for purposes of Section 5.02 has
determined in its sole discretion that any such modifications to this Agreement
will neither adversely affect the rating on the Certificates nor give rise to a
risk that either of the Upper-Tier REMIC or the Lower-Tier REMIC or any of the
Certificateholders will be subject to a tax caused by a transfer to a
non-permitted transferee, (vii) to make certain provisions with respect to the
denominations of, and the manner of payments on, certain Classes of Certificates
initially retained by the Depositor or an affiliate of the Depositor and (viii)
to make any other provisions with respect to matters or questions arising under
this Agreement or such Custodial Agreement which shall not be materially
inconsistent with the provisions of this Agreement, provided that such action
shall not, as evidenced by an Opinion of Counsel, adversely affect in any
material respect the interests of any Certificateholder. Notwithstanding the
foregoing, any amendment pursuant to clause (v) or (viii) shall not be deemed to
adversely affect in any material respect the interest of Certificateholders and
no Opinion of Counsel to that effect shall be required if the person requesting
the amendment instead obtains a letter from each Rating Agency stating that the
amendment would not result in the downgrading or withdrawal of the respective
ratings then assigned to the Certificates.

            This Agreement or the Custodial Agreement may also be amended from
time to time by the Depositor, the Master Servicer and the Trustee with the
consent of the Holders of Certificates evidencing in the aggregate not less than
66-2/3% of the aggregate Voting Interests of each Class of Certificates affected
thereby, for the purpose of adding any provisions to or changing in any manner
or eliminating any of the provisions of this Agreement or such Custodial
Agreement or of modifying in any manner the rights of the Holders of
Certificates of such Class; provided, however, that no such amendment shall (i)
reduce in any manner the amount of, or delay the timing of, payments received on
Mortgage Loans which are required to be distributed on any Certificate without
the consent of the Holder of such Certificate, (ii) adversely affect in any
material respect the interest of the Holders of Certificates of any Class in a
manner other than as described in clause (i) hereof without the consent of
Holders of Certificates of such Class evidencing, as to such Class, Voting
Interests aggregating not less than 66-2/3% or (iii) reduce the aforesaid
percentage of Certificates of any Class the Holders of which are required to
consent to any such amendment, without the consent of the Holders of all
Certificates of such Class then outstanding.

            Notwithstanding any contrary provision of this Agreement, the
Trustee shall not consent to any amendment to this Agreement unless it shall
have first received an Opinion of Counsel to the effect that such amendment will
not subject either of the Upper-Tier REMIC or the Lower-Tier REMIC to tax or
cause either of the Upper-Tier REMIC or the Lower-Tier REMIC to fail to qualify
as a REMIC at any time that any Certificates are outstanding.

            Promptly after the execution of any amendment requiring the consent
of Certificateholders, the Trustee shall furnish written notification of the
substance of such amendment to each Certificateholder.

            It shall not be necessary for the consent of Certificateholders
under this Section 10.01(a) to approve the particular form of any proposed
amendment, but it shall be sufficient if such consent shall approve the
substance thereof. The manner of obtaining such consents and of evidencing the
authorization of the execution thereof by Certificateholders shall be subject to
such reasonable regulations as the Trustee may prescribe.

            The Trustee shall give prompt written notice to the Custodian of any
amendment or supplement to this Agreement and furnish the Custodian with written
copies thereof.

            The Master Servicer shall give prompt written notice to the
Counterparty of any amendment or supplement to this Agreement and furnish the
Counterparty with written copies thereof.

            (b) Notwithstanding any contrary provision of this Agreement, if any
of the Mortgage Loans are Type 2 Mortgage Loans, as indicated on the Mortgage
Loan Schedule, the Master Servicer may, from time to time, amend Schedule I
hereto without the consent of any Certificateholder or the Trustee; provided,
however, (i) that such amendment does not conflict with any provisions of the
related Servicing Agreement, (ii) that the related Servicing Agreement provides
for the remittance of each type of Unscheduled Principal Receipts received by
such Servicer during the Applicable Unscheduled Principal Receipt Period (as so
amended) related to each Distribution Date to the Master Servicer no later than
the 24th day of the month in which such Distribution Date occurs and (iii) that
such amendment is for the purpose of changing the Applicable Unscheduled
Principal Receipt Period for Type 2 Mortgage Loans to a Mid-Month Receipt Period
with respect to all Unscheduled Principal Receipts.

            Section 10.02 Recordation of Agreement.

            This Agreement (or an abstract hereof, if acceptable to the
applicable recording office) is subject to recordation in all appropriate public
offices for real property records in all the towns or other comparable
jurisdictions in which any or all of the Mortgaged Properties are situated, and
in any other appropriate public office or elsewhere, such recordation to be
effected by the Master Servicer and at its expense on direction by the Trustee,
but only upon direction accompanied by an Opinion of Counsel to the effect that
such recordation materially and beneficially affects the interests of the
Certificateholders.

            For the purpose of facilitating the recordation of this Agreement as
herein provided and for other purposes, this Agreement may be executed
simultaneously in any number of counterparts, each of which counterparts shall
be deemed to be an original, and such counterparts shall constitute but one and
the same instrument.

            Section 10.03 Limitation on Rights of Certificateholders.

            The death or incapacity of any Certificateholder shall not operate
to terminate this Agreement or the Trust Estate, nor entitle such
Certificateholder's legal representatives or heirs to claim an accounting or
take any action or proceeding in any court for a partition or winding up of the
Trust Estate, nor otherwise affect the rights, obligations and liabilities of
the parties hereto or any of them.

            Except as otherwise expressly provided herein, no Certificateholder,
solely by virtue of its status as a Certificateholder, shall have any right to
vote or in any manner otherwise control the operation and management of the
Trust Estate, or the obligations of the parties hereto, nor shall anything
herein set forth, or contained in the terms of the Certificates, be construed so
as to constitute the Certificateholders from time to time as partners or members
of an association, nor shall any Certificateholder be under any liability to any
third person by reason of any action taken by the parties to this Agreement
pursuant to any provision hereof.

            No Certificateholder, solely by virtue of its status as
Certificateholder, shall have any right by virtue or by availing of any
provision of this Agreement to institute any suit, action or proceeding in
equity or at law upon or under or with respect to this Agreement, unless such
Holder previously shall have given to the Trustee a written notice of default
and of the continuance thereof, as hereinbefore provided, and unless the Holders
of Certificates evidencing not less than 25% of the Voting Interest represented
by all Certificates shall have made written request upon the Trustee to
institute such action, suit or proceeding in its own name as Trustee hereunder
and shall have offered to the Trustee such reasonable indemnity as it may
require against the cost, expenses and liabilities to be incurred therein or
thereby, and the Trustee, for 60 days after its receipt of such notice, request
and offer of indemnity, shall have neglected or refused to institute any such
action, suit or proceeding; it being understood and intended, and being
expressly covenanted by each Certificateholder with every other
Certificateholder and the Trustee, that no one or more Holders of Certificates
shall have any right in any manner whatever by virtue or by availing of any
provision of this Agreement to affect, disturb or prejudice the rights of the
Holders of any other of such Certificates, or to obtain or seek to obtain
priority over or preference to any other such Holder, or to enforce any right
under this Agreement, except in the manner herein provided and for the benefit
of all Certificateholders. For the protection and enforcement of the provisions
of this Section, each and every Certificateholder and the Trustee shall be
entitled to such relief as can be given either at law or in equity.

            Section 10.04 Governing Law; Jurisdiction.

            This Agreement shall be construed in accordance with the laws of the
State of New York (without regard to conflicts of laws principles), and the
obligations, rights and remedies of the parties hereunder shall be determined in
accordance with such laws.

            Section 10.05 Notices.

            Unless otherwise provided in this Agreement, all demands, notices
and communications hereunder shall be in writing and shall be deemed to have
been duly given if personally delivered at or mailed by certified or registered
mail, return receipt requested or by facsimile (i) in the case of the Depositor,
to Wells Fargo Asset Securities Corporation, 7430 New Technology Way, Frederick,
Maryland 21703, Attention: Vice President, Structured Finance or such other
address as may hereafter be furnished to the Master Servicer and the Trustee in
writing by the Depositor, (ii) in the case of the Master Servicer, to Wells
Fargo Bank, N.A., 9062 Old Annapolis Road, Columbia, Maryland 21045-1951,
Attention: Corporate Trust Services-WFMBS 2007-4; facsimile: (410) 715-2380 or
such other address as may hereafter be furnished to the Depositor and the
Trustee in writing by the Master Servicer and (iii) in the case of the Trustee
or the Paying Agent, to the Corporate Trust Office, or such other address as may
hereafter be furnished to the Depositor and the Master Servicer in writing by
the Trustee or the Paying Agent. Any notice required or permitted to be mailed
to a Certificateholder shall be given by first class mail, postage prepaid, at
the address of such Holder as shown in the Certificate Register. Any notice
mailed or transmitted within the time prescribed in this Agreement shall be
conclusively presumed to have been duly given, whether or not the addressee
receives such notice; provided, however, that any demand, notice or
communication to or upon the Depositor, the Master Servicer or the Trustee shall
not be effective until received.

            For all purposes of this Agreement, in the absence of actual
knowledge by an officer of the Master Servicer, the Master Servicer shall not be
deemed to have knowledge of any act or failure to act of any Servicer unless
notified thereof in writing by the Trustee, the applicable Servicer or a
Certificateholder.

            Section 10.06 Severability of Provisions.

            If any one or more of the covenants, agreements, provisions or terms
of this Agreement shall be for any reason whatsoever held invalid, then such
covenants, agreements, provisions or terms shall be deemed severable from the
remaining covenants, agreements, provisions or terms of this Agreement and shall
in no way affect the validity or enforceability of the other provisions of this
Agreement or of the Certificates or the rights of the Holders thereof.

            Section 10.07 Special Notices to Rating Agencies.

            (a) The Trustee shall give prompt notice to each Rating Agency of
the occurrence of any of the following events of which a Responsible Officer has
notice:

            (i) any amendment to this Agreement pursuant to Section 10.01(a);

            (ii) any assignment by the Master Servicer of its rights and
      delegation of its duties pursuant to Section 6.06;

            (iii) any resignation of the Master Servicer pursuant to Section
      6.04;

            (iv) the occurrence of any of the Events of Default described in
      Section 7.01;

            (v) any notice of termination given to the Master Servicer pursuant
      to Section 7.01; or

            (vi) the appointment of any successor to the Master Servicer
      pursuant to Section 7.05.

            (b) The Paying Agent shall give prompt notice to each Rating Agency
of any sale or transfer of the Class B Certificates pursuant to Section 5.02 to
an affiliate of the Depositor.

            (c) The Paying Agent shall give prompt notice to each Rating Agency
of the making of a final payment pursuant to Section 9.01.

            (d) The Master Servicer shall give prompt notice to each Rating
Agency of the occurrence of any of the following events:

            (i) the resignation of the Custodian or the appointment of a
      successor Custodian pursuant to the Custodial Agreement;

            (ii) the resignation or removal of the Trustee pursuant to Section
      8.08;

            (iii) the appointment of a successor trustee pursuant to Section
      8.09; or

            (iv) the sale, transfer or other disposition in a single transaction
      of 50% or more of the equity interests in the Master Servicer.

            (e) The Master Servicer shall deliver to each Rating Agency or
otherwise make available to each Rating Agency in a format acceptable to each
Rating Agency:

            (i) reports prepared pursuant to Section 3.05 and 3.11; and

            (ii) the Distribution Date Statements.

            Section 10.08 Covenant of Depositor.

            The Depositor shall not amend Article Third of its Certificate of
Incorporation without the prior written consent of each Rating Agency rating the
Certificates.

            Section 10.09 Recharacterization.

            The Parties intend the conveyance by the Depositor to the Trustee of
all of its right, title and interest in and to the Trust Estate pursuant to this
Agreement to constitute a purchase and sale and not a loan. Notwithstanding the
foregoing, to the extent that such conveyance is held not to constitute a sale
under applicable law, it is intended that this Agreement shall constitute a
security agreement under applicable law and that the Depositor shall be deemed
to have granted to the Trustee a first priority security interest in all of the
Depositor's right, title and interest in and to the Trust Estate. The Master
Servicer shall take all actions, including, without limitation, filing any
Uniform Commercial Code continuation statements, as shall be necessary to
perfect or maintain the perfection of such security interest.

            Section 10.10 Regulation AB Compliance; Intent of Parties;
Reasonableness. The parties hereto acknowledge that interpretations of the
requirements of Regulation AB may change over time, whether due to interpretive
guidance provided by the Commission or its staff, consensus among participants
in the asset-backed securities markets, advice of counsel, or otherwise, and
agree to comply with requests made by the Depositor or the Master Servicer in
good faith for delivery of information under these provisions on the basis of
evolving interpretations of Regulation AB. In connection with the Trust, the
parties hereto shall cooperate fully with the Master Servicer and the Depositor
to deliver to the Master Servicer and/or the Depositor, any and all statements,
reports, certifications, records and any other information available to such
party and reasonably necessary in the good faith determination of the Depositor
or the Master Servicer to permit the Depositor or the Master Servicer to comply
with the provisions of Regulation AB, together with such disclosures reasonably
believed by the Depositor or the Master Servicer to be necessary in order to
effect such compliance.

<PAGE>

                                   ARTICLE XI

                             TERMS FOR CERTIFICATES

            Section 11.01 Cut-Off Date.

            The Cut-Off Date for the Certificates is March 1, 2007.

            Section 11.02 Cut-Off Date Aggregate Principal Balance.

            The Cut-Off Date Aggregate Principal Balance is $1,800,061,020.35.

            Section 11.03 Original Class A Percentage.

            The Original Class A Percentage is 96.48023236%.

            Section 11.04 Original Principal Balances of the Classes of Class A
Certificates.

            As to the following Classes of Class A Certificates, the Principal
Balance of such Class as of the Cut-Off Date, as follows:

                                                 Original
                       Class                Principal Balance
                       -----                -----------------

              Class A-1                        $500,000,000.00
              Class A-2                         $13,580,000.00
              Class A-3                         $25,000,000.00
              Class A-4                        $158,630,000.00
              Class A-5                         $55,000,000.00
              Class A-6                            $555,000.00
              Class A-7                        $100,000,000.00
              Class A-8                         $56,592,000.00
              Class A-9                         $62,167,000.00
              Class A-10                            $12,000.00
              Class A-11                        $50,000,000.00
              Class A-12                         $4,713,000.00
              Class A-13                       $150,000,000.00
              Class A-14                        $64,000,000.00
              Class A-15                       $288,083,000.00
              Class A-16                        $86,550,000.00
              Class A-17                        $22,240,000.00
              Class A-18                         $3,290,000.00
              Class A-20                        $50,450,000.00
              Class A-21                        $36,100,000.00
              Class A-PO                        $10,096,322.00
              Class A-R                                $100.00

            Section 11.05 Original Notional Amount.

            The Original Class A-19 Notional Amount is $16,552,500.00.

            Section 11.06 Original Aggregate Non-PO Principal Balance.

            The Original Aggregate Non-PO Principal Balance is
$1,726,962,100.00.

            Section 11.07 Original Class B Principal Balance.

            The Original Class B Principal Balance is $63,002,598.00.

            Section 11.08 Original Principal Balances of the Classes of Class B
Certificates.

            As to the following Classes of Class B Certificate, the Principal
Balance of such Class as of the Cut-Off Date, is as follows:

                                             Original
                         Class           Principal Balance
                         -----           -----------------
                       Class B-1          $37,801,000.00
                       Class B-2          $10,801,000.00
                       Class B-3           $5,400,000.00
                       Class B-4           $3,600,000.00
                       Class B-5           $2,700,000.00
                       Class B-6           $2,700,598.00

            Section 11.09 Original Class B-1 Fractional Interest.

            The Original Class B-1 Fractional Interest is 1.40793828%.

            Section 11.10 Original Class B-2 Fractional Interest.

            The Original Class B-2 Fractional Interest is 0.80451855%.

            Section 11.11 Original Class B-3 Fractional Interest.

            The Original Class B-3 Fractional Interest is 0.50283663%.

            Section 11.12 Original Class B-4 Fractional Interest.

            The Original Class B-4 Fractional Interest is 0.30171534%.

            Section 11.13 Original Class B-5 Fractional Interest.

            The Original Class B-5 Fractional Interest is 0.15087438%.

            Section 11.14 Original Class B-1 Percentage.

            The Original Class B-1 Percentage is 2.11182936%.

            Section 11.15 Original Class B-2 Percentage.

            The Original Class B-2 Percentage is 0.60341972%.

            Section 11.16 Original Class B-3 Percentage.

            The Original Class B-3 Percentage is 0.30168193%.

            Section 11.17 Original Class B-4 Percentage.

            The Original Class B-4 Percentage is 0.20112128%.

            Section 11.18 Original Class B-5 Percentage.

            The Original Class B-5 Percentage is 0.15084096%.

            Section 11.19 Original Class B-6 Percentage.

            The Original Class B-6 Percentage is 0.15087438%.

            Section 11.20 Closing Date.

            The Closing Date is March 28, 2007.

            Section 11.21 Right to Purchase.

            The right of the Depositor to purchase all of the Mortgage Loans
pursuant to Section 9.01 hereof shall be conditioned upon the aggregate
Scheduled Principal Balance of the Mortgage Loans being less than
$180,006,102.04 (10% of the Cut-Off Date Aggregate Principal Balance) at the
time of any such purchase.

            Section 11.22 Single Certificate.

            A Single Certificate for the Class A-1, Class A-3, Class A-4, Class
A-5, Class A-7, Class A-9, Class A-11, Class A-13, Class A-15, Class A-16, Class
A-17, Class A-20 and Class A-21 Certificates represents a $25,000 Denomination.
A Single Certificate for the Class A-10 Certificates represents a $12,000
Denomination. A Single Certificate for the Class A-19 Certificates represents a
$613,000 Denomination. A Single Certificate for the Class A-8, Class A-14 and
Class A-18 Certificates represents a $1,000 Denomination. A Single Certificate
for the Class A-2, Class A-6, Class A-12, Class A-PO, Class B-1, Class B-2 and
Class B-3 Certificates represents a $100,000 Denomination. A Single Certificate
for the Residual Certificate represents a $100 Denomination. A Single
Certificate for the Class B-4, Class B-5 and Class B-6 Certificates represents a
$250,000 Denomination.

            Section 11.23 Servicing Fee Rate.

            The rate used to calculate the Servicing Fee is equal to such rate
as is set forth on the Mortgage Loan Schedule with respect to a Mortgage Loan.

            Section 11.24 Master Servicing Fee Rate.

            The rate used to calculate the Master Servicing Fee for each
Mortgage Loan shall be 0.010% per annum.

<PAGE>

            IN WITNESS WHEREOF, the Depositor, the Master Servicer and the
Trustee have caused their names to be signed hereto by their respective officers
thereunto duly authorized, all as of the day and year first above written.


                                       WELLS FARGO ASSET SECURITIES
                                          CORPORATION
                                            as Depositor


                                       By: /s/ Bradley A. Davis
                                          --------------------------------------
                                          Name: Bradley A. Davis
                                          Title: Vice President


                                       WELLS FARGO BANK, N.A.
                                            as Master Servicer


                                       By: /s/ Carla S. Walker
                                          --------------------------------------
                                          Name: Carla S. Walker
                                          Title: Vice President


                                       HSBC BANK USA, NATIONAL ASSOCIATION
                                          as Trustee


                                       By: /s/ Fernando Acebedo
                                          --------------------------------------
                                          Name: Fernando Acebedo
                                          Title: Vice President

<PAGE>

STATE OF MARYLAND       )
                        ss.:
COUNTY OF FREDERICK     )


            On this 28th day of March, 2007, before me, a notary public in and
for the State of Maryland, personally appeared Bradley A. Davis, known to me
who, being by me duly sworn, did depose and say that he resides at Cooksville,
Maryland; that he is a Vice President of Wells Fargo Asset Securities
Corporation, a Delaware corporation, one of the parties that executed the
foregoing instrument; and that he signed his name thereto by order of the Board
of Directors of said corporation.



-------------------------
Notary Public

[NOTARIAL SEAL]

<PAGE>

STATE OF MARYLAND       )
                        ss.:
COUNTY OF               )

            On this 28th day of March, 2007, before me, a notary public in and
for the State of Maryland, personally appeared Carla S. Walker, known to me who,
being by me duly sworn, did depose and say that she resides in ____________,
Maryland; that she is a Vice President of Wells Fargo Bank, N.A, a national
banking association, one of the parties that executed the foregoing instrument;
and that she signed her name thereto by order of the Board of Directors of said
association.



-------------------------
Notary Public

[NOTARIAL SEAL]

<PAGE>

STATE OF NEW YORK             )
                              ss.:
COUNTY OF NEW YORK            )

            On this 28th day of March, 2007, before me, a notary public in and
for the State of New York, personally appeared Fernando Acebedo, known to me
who, being by me duly sworn, did depose and say that he resides in Huntington,
New York; that he is a Vice President of HSBC Bank USA, National Association, a
national banking association, one of the parties that executed the foregoing
instrument; and that he signed his name thereto by order of the Board of
Directors of said association.



-------------------------
Notary Public

[NOTARIAL SEAL]

<PAGE>

                                   SCHEDULE I

                    Wells Fargo Asset Securities Corporation,
                Mortgage Pass-Through Certificates, Series 2007-4
               Applicable Unscheduled Principal Receipt Period

                                   Full Unscheduled      Partial Unscheduled
Servicer                          Principal Receipts     Principal Receipts
------------------------------    ------------------     -------------------
Wells Fargo Bank                       Mid-Month              Mid-Month

<PAGE>

                                   SCHEDULE II

    Schedules of PAC I Group, PAC II Certificates and Scheduled Certificates

            The following tables set forth for each Distribution Date the
planned Principal Balances for the PAC I Group and the PAC II Certificates and
the scheduled Principal Balances for the Scheduled Certificates expressed as a
percentage of the initial aggregate Principal Balance of the PAC I Group,
initial Principal Balance of the PAC II Certificates and initial Principal
Balance of the Scheduled Certificates, respectively.

Planned Principal Balances as Percentages of Initial Aggregate Principal Balance
PAC I Group


                         Percentage of
                       Initial Aggregate
Distribution Date      Principal Balance
-----------------      -----------------
April 2007......         99.80891887%
May 2007........         99.57342738
June 2007.......         99.29392702
July 2007.......         98.97048435
August 2007.....         98.60319392
September 2007..         98.19217828
October 2007....         97.73758797
November 2007...         97.23960151
December 2007...         96.69842527
January 2008....         96.11429345
February 2008...         95.48746788
March 2008......         94.81823790
April 2008......         94.10692019
May 2008........         93.35385850
June 2008.......         92.55942345
July 2008.......         91.72401222
August 2008.....         90.84804828
September 2008..         89.93198104
October 2008....         88.97628546
November 2008...         87.98146172
December 2008...         86.94803476
January 2009....         85.87655382
February 2009...         84.76759202
March 2009......         83.62174582
April 2009......         82.43963453
May 2009........         81.22189971
June 2009.......         79.96920466
July 2009.......         78.68223377
August 2009.....         77.36235757
September 2009..         76.05121988
October 2009....         74.74876421
November 2009...         73.45493443
December 2009...         72.16967479
January 2010....         70.89292989
February 2010...         69.62464470
March 2010......         68.36476453
April 2010......         67.11323506
May 2010........         65.87000233
June 2010.......         64.63501271
July 2010.......         63.40821293
August 2010.....         62.18955009
September 2010..         60.97897159
October 2010....         59.77642520
November 2010...         58.58185903
December 2010...         57.39522152
January 2011....         56.21646145
February 2011...         55.04552792
March 2011......         53.88237038
April 2011......         52.72693860
May 2011........         51.57918269
June 2011.......         50.43905306
July 2011.......         49.30650047
August 2011.....         48.18147598
September 2011..         47.06393096
October 2011....         45.95381714
November 2011...         44.85108653
December 2011...         43.75569145
January 2012....         42.66758454
February 2012...         41.58671877
March 2012......         40.51304737
April 2012......         39.57232426
May 2012........         38.63854003
June 2012.......         37.71164938
July 2012.......         36.79160726
August 2012.....         35.87836897
September 2012..         34.97189006
October 2012....         34.07212639
November 2012...         33.17903411
December 2012...         32.29256966
January 2013....         31.41268976
February 2013...         30.53935141
March 2013......         29.67251192
April 2013......         28.84280752
May 2013........         28.01932977
June 2013.......         27.20203726
July 2013.......         26.39088878
August 2013.....         25.58584345
September 2013..         24.78686063
October 2013....         23.99389996
November 2013...         23.20692135
December 2013...         22.42588494
January 2014....         21.65075119
February 2014...         20.88148078
March 2014......         20.11803466
April 2014......         19.49691897
May 2014........         18.88934073
June 2014.......         18.29504220
July 2014.......         17.71377029
August 2014.....         17.14527636
September 2014..         16.58931628
October 2014....         16.04565024
November 2014...         15.51404271
December 2014...         14.99426241
January 2015....         14.48608216
February 2015...         13.98927889
March 2015......         13.50363348
April 2015......         13.14948186
May 2015........         12.80307470
June 2015.......         12.46425834
July 2015.......         12.13288196
August 2015.....         11.80879759
September 2015..         11.49186001
October 2015....         11.18192675
November 2015...         10.87885799
December 2015...         10.58251657
January 2016....         10.29276787
February 2016...         10.00947984
March 2016......          9.73252288
April 2016......          9.56348425
May 2016........          9.39732367
June 2016.......          9.23399276
July 2016.......          9.07344393
August 2016.....          8.91563039
September 2016..          8.76050615
October 2016....          8.60802595
November 2016...          8.45814531
December 2016...          8.31082049
January 2017....          8.16600848
February 2017...          8.02366697
March 2017......          7.87835069
April 2017......          7.73557154
May 2017........          7.59528619
June 2017.......          7.45745203
July 2017.......          7.32202718
August 2017.....          7.18897044
September 2017..          7.05824134
October 2017....          6.92980007
November 2017...          6.80360749
December 2017...          6.67962512
January 2018....          6.55781516
February 2018...          6.43814040
March 2018......          6.32056428
April 2018......          6.20505087
May 2018........          6.09156482
June 2018.......          5.98007140
July 2018.......          5.87053645
August 2018.....          5.76292640
September 2018..          5.65720824
October 2018....          5.55334950
November 2018...          5.45131830
December 2018...          5.35108326
January 2019....          5.25261355
February 2019...          5.15587886
March 2019......          5.06084937
April 2019......          4.96749581
May 2019........          4.87578935
June 2019.......          4.78570170
July 2019.......          4.69720500
August 2019.....          4.61027191
September 2019..          4.52487551
October 2019....          4.44098936
November 2019...          4.35858746
December 2019...          4.27764424
January 2020....          4.19813460
February 2020...          4.12003382
March 2020......          4.04331762
April 2020......          3.96796213
May 2020........          3.89394388
June 2020.......          3.82123981
July 2020.......          3.74982725
August 2020.....          3.67968388
September 2020..          3.61078782
October 2020....          3.54311750
November 2020...          3.47665175
December 2020...          3.41136976
January 2021....          3.34725106
February 2021...          3.28427553
March 2021......          3.22242340
April 2021......          3.16167523
May 2021........          3.10201190
June 2021.......          3.04341463
July 2021.......          2.98586497
August 2021.....          2.92934474
September 2021..          2.87383612
October 2021....          2.81932156
November 2021...          2.76578382
December 2021...          2.71320595
January 2022....          2.66157130
February 2022...          2.61086348
March 2022......          2.55952143
April 2022......          2.50911694
May 2022........          2.45963354
June 2022.......          2.41105508
July 2022.......          2.36336566
August 2022.....          2.31654968
September 2022..          2.27059178
October 2022....          2.22547688
November 2022...          2.18119015
December 2022...          2.13771702
January 2023....          2.09504317
February 2023...          2.05315452
March 2023......          2.01203725
April 2023......          1.97167774
May 2023........          1.93206264
June 2023.......          1.89317881
July 2023.......          1.85501336
August 2023.....          1.81755359
September 2023..          1.78078703
October 2023....          1.74470143
November 2023...          1.70928476
December 2023...          1.67452516
January 2024....          1.64041103
February 2024...          1.60693091
March 2024......          1.57407358
April 2024......          1.54182801
May 2024........          1.51018334
June 2024.......          1.47912890
July 2024.......          1.44865422
August 2024.....          1.41874900
September 2024..          1.38940311
October 2024....          1.36060663
November 2024...          1.33234976
December 2024...          1.30462291
January 2025....          1.27741664
February 2025...          1.25072167
March 2025......          1.22452888
April 2025......          1.19882933
May 2025........          1.17361419
June 2025.......          1.14887483
July 2025.......          1.12460275
August 2025.....          1.10078959
September 2025..          1.07742715
October 2025....          1.05450735
November 2025...          1.03202227
December 2025...          1.00996412
January 2026....          0.98832525
February 2026...          0.96709813
March 2026......          0.94627539
April 2026......          0.92584974
May 2026........          0.90581407
June 2026.......          0.88616135
July 2026.......          0.86688470
August 2026.....          0.84797734
September 2026..          0.82943263
October 2026....          0.81124403
November 2026...          0.79340510
December 2026...          0.77590956
January 2027....          0.75875119
February 2027...          0.74192389
March 2027......          0.72543831
April 2027......          0.70927147
May 2027........          0.69341762
June 2027.......          0.67787108
July 2027.......          0.66262628
August 2027.....          0.64767775
September 2027..          0.63302011
October 2027....          0.61864808
November 2027...          0.60455647
December 2027...          0.59074017
January 2028....          0.57719419
February 2028...          0.56391358
March 2028......          0.55089352
April 2028......          0.53812926
May 2028........          0.52561612
June 2028.......          0.51334952
July 2028.......          0.50132496
August 2028.....          0.48953801
September 2028..          0.47798430
October 2028....          0.46665958
November 2028...          0.45555964
December 2028...          0.44468037
January 2029....          0.43401771
February 2029...          0.42356767
March 2029......          0.41332635
April 2029......          0.40328991
May 2029........          0.39345457
June 2029.......          0.38381662
July 2029.......          0.37437244
August 2029.....          0.36511842
September 2029..          0.35605107
October 2029....          0.34716693
November 2029...          0.33846260
December 2029...          0.32993477
January 2030....          0.32158014
February 2030...          0.31339552
March 2030......          0.30537774
April 2030......          0.29752370
May 2030........          0.28983035
June 2030.......          0.28229470
July 2030.......          0.27491382
August 2030.....          0.26768481
September 2030..          0.26060483
October 2030....          0.25367111
November 2030...          0.24688090
December 2030...          0.24023152
January 2031....          0.23372033
February 2031...          0.22734473
March 2031......          0.22110218
April 2031......          0.21499018
May 2031........          0.20900627
June 2031.......          0.20314804
July 2031.......          0.19741311
August 2031.....          0.19179917
September 2031..          0.18630392
October 2031....          0.18092512
November 2031...          0.17566056
December 2031...          0.17050809
January 2032....          0.16546556
February 2032...          0.16053090
March 2032......          0.15570484
April 2032......          0.15098250
May 2032........          0.14636190
June 2032.......          0.14184111
July 2032.......          0.13741822
August 2032.....          0.13309136
September 2032..          0.12885868
October 2032....          0.12471840
November 2032...          0.12066872
December 2032...          0.11670791
January 2033....          0.11283426
February 2033...          0.10904610
March 2033......          0.10534177
April 2033......          0.10171966
May 2033........          0.09817819
June 2033.......          0.09471577
July 2033.......          0.09133090
August 2033.....          0.08802205
September 2033..          0.08478777
October 2033....          0.08162658
November 2033...          0.07853708
December 2033...          0.07551786
January 2034....          0.07256756
February 2034...          0.06968482
March 2034......          0.06686831
April 2034......          0.06411675
May 2034........          0.06142886
June 2034.......          0.05880338
July 2034.......          0.05623909
August 2034.....          0.05373478
September 2034..          0.05128926
October 2034....          0.04890137
November 2034...          0.04656998
December 2034...          0.04429395
January 2035....          0.04207219
February 2035...          0.03990363
March 2035......          0.03778719
April 2035......          0.03572184
May 2035........          0.03370656
June 2035.......          0.03174035
July 2035.......          0.02982221
August 2035.....          0.02795119
September 2035..          0.02612634
October 2035....          0.02434673
November 2035...          0.02261143
December 2035...          0.02091956
January 2036....          0.01927024
February 2036...          0.01766260
March 2036......          0.01609580
April 2036......          0.01456900
May 2036........          0.01308139
June 2036.......          0.01163217
July 2036.......          0.01022054
August 2036.....          0.00884574
September 2036..          0.00750701
October 2036....          0.00620361
November 2036...          0.00493481
December 2036...          0.00369989
January 2037....          0.00113899
February 2037
and thereafter..          0.00000000

<PAGE>

Planned Principal Balances as Percentages of Initial Principal Balance PAC II
Certificates

                         Percentage
                         of Initial
Distribution Date     Principal Balance
-----------------     -----------------
April 2007.......       99.80752037%
May 2007.........       99.52092240
June 2007........       99.13907435
July 2007........       98.66212335
August 2007......       98.09037817
September 2007...       97.42430968
October 2007.....       96.66455122
November 2007....       95.81189855
December 2007....       94.86730944
January 2008.....       93.83190291
February 2008....       92.70695810
March 2008.......       91.49391285
April 2008.......       90.19436183
May 2008.........       88.81005443
June 2008........       87.34289215
July 2008........       85.79492575
August 2008......       84.16835210
September 2008...       82.46551053
October 2008.....       80.68887896
November 2008....       78.84106968
December 2008....       76.92482484
January 2009.....       74.94301158
February 2009....       72.89861687
March 2009.......       70.79474208
April 2009......        68.63459729
May 2009........        66.42149526
June 2009.......        64.15884529
July 2009.......        61.85014667
August 2009.....        59.50036669
September 2009..        57.19818156
October 2009....        54.94291835
November 2009...        52.73391256
December 2009...        50.57050795
January 2010....        48.45205661
February 2010...        46.37791870
March 2010......        44.34746245
April 2010......        42.36006397
May 2010........        40.41510729
June 2010.......        38.51198414
July 2010.......        36.65009392
August 2010.....        34.82884361
September 2010..        33.04764766
October 2010....        31.30592790
November 2010...        29.60311348
December 2010...        27.93864077
January 2011....        26.31195324
February 2011...        24.72250142
March 2011......        23.16974279
April 2011......        21.65314173
May 2011........        20.17216938
June 2011.......        18.72630362
July 2011.......        17.31502895
August 2011.....        15.93783644
September 2011..        14.59422364
October 2011....        13.28369444
November 2011...        12.00575912
December 2011...        10.75993418
January 2012....         9.54574227
February 2012...         8.36271219
March 2012......         7.21037872
April 2012......         6.30802921
May 2012........         5.43397771
June 2012.......         4.58778141
July 2012.......         3.76900322
August 2012.....         2.97721166
September 2012..         2.21198086
October 2012....         1.47289047
November 2012...         0.75952557
December 2012...         0.07147667
January 2013 and
   thereafter...         0.00000000

<PAGE>

Scheduled Principal Balances as Percentages of Initial Principal Balance
Scheduled Certificates

                         Percentage
                         of Initial
Distribution Date     Principal Balance
-----------------     -----------------
April 2007.......       99.99484545%
May 2007.........       99.98966515
June 2007........       99.98445891
July 2007........       99.97922667
August 2007......       99.97396825
September 2007...       99.96868355
October 2007.....       99.96337242
November 2007....       99.95803475
December 2007....       99.95267036
January 2008.....       99.94727918
February 2008....       99.94186102
March 2008.......       99.93641578
April 2008.......       99.93094331
May 2008.........       99.92544349
June 2008........       99.91991616
July 2008........       99.91436120
August 2008......       99.90877845
September 2008...       99.90316780
October 2008.....       99.89752909
November 2008....       99.89186220
December 2008....       99.88616696
January 2009.....       99.88044325
February 2009....       99.87469093
March 2009.......       99.86890984
April 2009.......       99.86309984
May 2009.........       99.85726078
June 2009........       99.85139255
July 2009........       99.84549496
August 2009......       99.83956789
September 2009...       99.83361118
October 2009.....       99.82762469
November 2009....       99.82160827
December 2009....       99.81556176
January 2010.....       99.80948504
February 2010....       99.80337791
March 2010.......       99.79724025
April 2010.......       99.79107191
May 2010.........       99.78487273
June 2010........       99.77864255
July 2010........       99.77238122
August 2010......       99.76608858
September 2010...       99.75976447
October 2010.....       99.75340875
November 2010....       99.74702125
December 2010....       99.74060180
January 2011.....       99.73415027
February 2011....       99.72766647
March 2011.......       99.72115027
April 2011.......       99.71460147
May 2011.........       99.70801993
June 2011........       99.70140549
July 2011........       99.69475796
August 2011......       99.68807722
September 2011...       99.68136305
October 2011.....       99.67461533
November 2011....       99.66783385
December 2011....       99.66101847
January 2012.....       99.65416902
February 2012....       99.64728533
March 2012.......       99.64036720
April 2012.......       99.63341449
May 2012.........       99.62642702
June 2012........       99.61940462
July 2012........       99.61234709
August 2012......       99.60525427
September 2012...       99.59812600
October 2012.....       99.59096209
November 2012....       99.58376236
December 2012....       99.57652662
January 2013.....       99.56925471
February 2013....       99.56194644
March 2013.......       99.55460162
April 2013.......       99.54722009
May 2013.........       99.53980164
June 2013........       99.53234611
July 2013........       99.52485329
August 2013......       99.51732302
September 2013...       99.50975507
October 2013.....       99.50214931
November 2013....       99.49450551
December 2013....       99.48682349
January 2014.....       99.47910307
February 2014....       99.47134404
March 2014.......       99.46354622
April 2014.......       99.45570940
May 2014.........       99.44783340
June 2014........       99.43991802
July 2014........       99.43196307
August 2014......       99.42396833
September 2014...       99.41593364
October 2014.....       99.40785875
November 2014....       99.39974351
December 2014....       99.39158767
January 2015.....       99.38339107
February 2015....       99.37515347
March 2015.......       99.36687469
April 2015.......       99.35855453
May 2015.........       99.35019275
June 2015........       99.34178916
July 2015........       99.33334356
August 2015......       99.32485575
September 2015...       99.31632547
October 2015.....       99.30775256
November 2015....       99.29913678
December 2015....       99.29047791
January 2016.....       99.28177576
February 2016....       99.27303009
March 2016.......       99.26424069
April 2016.......       99.25540736
May 2016.........       99.24652985
June 2016........       99.23760795
July 2016........       99.22864145
August 2016......       99.21963011
September 2016...       99.21057371
October 2016.....       99.20147204
November 2016....       99.19232485
December 2016....       99.18313193
January 2017.....       99.17389304
February 2017....       99.16460796
March 2017.......       99.15527645
April 2017.......       99.14589829
May 2017.........       99.13647324
June 2017........       99.12700105
July 2017........       99.11748153
August 2017......       99.10791438
September 2017...       99.09829942
October 2017.....       99.08863636
November 2017....       99.07892500
December 2017....       99.06916507
January 2018.....       99.05935636
February 2018....       99.04949860
March 2018.......       99.03959155
April 2018.......       99.02963495
May 2018.........       99.01962858
June 2018........       99.00957218
July 2018........       98.99946549
August 2018......       98.98930827
September 2018...       98.97910027
October 2018.....       98.96884124
November 2018....       98.95853089
December 2018....       98.94816900
January 2019.....       98.93775529
February 2019....       98.92728953
March 2019.......       98.91677144
April 2019.......       98.90620075
May 2019.........       98.89557720
June 2019........       98.88490055
July 2019........       98.87417049
August 2019......       98.86338680
September 2019...       98.85254920
October 2019.....       98.84165740
November 2019....       98.83071115
December 2019....       98.81971015
January 2020.....       98.80865415
February 2020....       98.79754287
March 2020.......       98.78637605
April 2020.......       98.77515338
May 2020.........       98.76387460
June 2020........       98.75253944
July 2020........       98.74114758
August 2020......       98.72969878
September 2020...       98.71819273
October 2020.....       98.03490956
November 2020....       97.10842769
December 2020....       96.18735015
January 2021.....       95.27167251
February 2021....       94.36138971
March 2021.......       93.45649605
April 2021.......       92.55698527
May 2021.........       91.66285045
June 2021........       90.77408418
July 2021........       89.89067836
August 2021......       89.01262447
September 2021...       88.13991340
October 2021.....       87.27253551
November 2021....       86.41048065
December 2021....       85.55373825
January 2022.....       84.70229715
February 2022....       83.85614582
March 2022.......       82.96367504
April 2022.......       82.07691035
May 2022.........       81.19583707
June 2022........       80.32044011
July 2022........       79.45070385
August 2022......       78.58661238
September 2022...       77.72814929
October 2022.....       76.87529784
November 2022....       76.02804089
December 2022....       75.18636095
January 2023.....       74.35024016
February 2023....       73.51966035
March 2023.......       72.69460298
April 2023.......       71.87504922
May 2023.........       71.06097991
June 2023........       70.25237560
July 2023........       69.44921656
August 2023......       68.65148271
September 2023...       67.85915384
October 2023.....       67.07220929
November 2023....       66.29062831
December 2023....       65.51438985
January 2024.....       64.74347258
February 2024....       63.97785500
March 2024.......       63.21751536
April 2024.......       62.46243171
May 2024.........       61.71258191
June 2024........       60.96794360
July 2024........       60.22849427
August 2024......       59.49421116
September 2024...       58.76507144
October 2024.....       58.04105200
November 2024....       57.32212965
December 2024....       56.60828104
January 2025.....       55.89948265
February 2025....       55.19571084
March 2025.......       54.49694184
April 2025.......       53.80315173
May 2025.........       53.11431651
June 2025........       52.43041204
July 2025........       51.75141405
August 2025......       51.07729824
September 2025...       50.40804015
October 2025.....       49.74361524
November 2025....       49.08399889
December 2025....       48.42916645
January 2026.....       47.77909313
February 2026....       47.13375407
March 2026.......       46.49312438
April 2026.......       45.85717911
May 2026.........       45.22589322
June 2026........       44.59924164
July 2026........       43.97719929
August 2026......       43.35974098
September 2026...       42.74684153
October 2026.....       42.13847569
November 2026....       41.53461825
December 2026....       40.93524389
January 2027.....       40.34032733
February 2027....       39.74984322
March 2027.......       39.16474109
April 2027.......       38.58401153
May 2027.........       38.00762927
June 2027........       37.43556900
July 2027........       36.86780540
August 2027......       36.30431322
September 2027...       35.74506713
October 2027.....       35.19004187
November 2027....       34.63921218
December 2027....       34.09255282
January 2028.....       33.55003851
February 2028....       33.01164411
March 2028.......       32.47734438
April 2028.......       31.94711418
May 2028.........       31.42092840
June 2028........       30.89876189
July 2028........       30.38058964
August 2028......       29.86638658
September 2028...       29.35612776
October 2028.....       28.84978824
November 2028....       28.34734305
December 2028....       27.84876740
January 2029.....       27.35403644
February 2029....       26.86312542
March 2029.......       26.37600964
April 2029.......       25.89266444
May 2029.........       25.41306522
June 2029........       24.93718744
July 2029........       24.46500658
August 2029......       23.99649829
September 2029...       23.53163815
October 2029.....       23.07040187
November 2029....       22.61276525
December 2029....       22.15870411
January 2030.....       21.70819435
February 2030....       21.26121193
March 2030.......       20.81773293
April 2030.......       20.37773344
May 2030.........       19.94118965
June 2030........       19.50807785
July 2030........       19.07837436
August 2030......       18.65205564
September 2030...       18.22909815
October 2030.....       17.80947849
November 2030....       17.39317329
December 2030....       16.98015936
January 2031.....       16.57041345
February 2031....       16.16391253
March 2031.......       15.76063353
April 2031.......       15.36055358
May 2031.........       14.96364982
June 2031........       14.56989953
July 2031........       14.17928000
August 2031......       13.79176873
September 2031...       13.40734318
October 2031.....       13.02598096
November 2031....       12.64765982
December 2031....       12.27235749
January 2032.....       11.90005189
February 2032....       11.53072098
March 2032.......       11.16462458
April 2032.......       10.80145638
May 2032.........       10.44119462
June 2032........       10.08381769
July 2032........        9.72930404
August 2032......        9.37763222
September 2032...        9.02878093
October 2032.....        8.68272885
November 2032....        8.33945491
December 2032....        7.99893798
January 2033.....        7.66115718
February 2033....        7.32609156
March 2033.......        6.99372044
April 2033.......        6.66402307
May 2033.........        6.33697895
June 2033........        6.01256756
July 2033........        5.69076858
August 2033......        5.37156171
September 2033...        5.05492676
October 2033.....        4.74084367
November 2033....        4.42929245
December 2033....        4.12025327
January 2034.....        3.81370629
February 2034....        3.50963185
March 2034.......        3.20801040
April 2034.......        2.90882240
May 2034.........        2.61204851
June 2034........        2.31766945
July 2034........        2.02566602
August 2034......        1.73601913
September 2034...        1.44870980
October 2034.....        1.16371916
November 2034....        0.88102840
December 2034....        0.60061885
January 2035.....        0.32247193
February 2035....        0.04656909
March 2035
   and thereafter        0.00000000

<PAGE>


                                   EXHIBIT A-1
                     [FORM OF FACE OF CLASS A-1 CERTIFICATE]


  [UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
   DEPOSITORY TRUST COMPANY TO THE DEPOSITOR OR ITS AGENT FOR REGISTRATION OF
 TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE
       NAME OF CEDE & CO. OR SUCH OTHER NAME AS REQUESTED BY AN AUTHORIZED
 REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY AND ANY PAYMENT IS MADE TO CEDE
 & CO., ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO
  ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN
                                INTEREST HEREIN.]

                        MORTGAGE PASS-THROUGH CERTIFICATE
                            SERIES 2007-4, CLASS A-1

            evidencing an interest in a pool of fixed interest rate,
            monthly pay, first lien, one- to four-family residential
                             mortgage loans sold by

                    WELLS FARGO ASSET SECURITIES CORPORATION
               (Not an interest in or obligation of the Depositor)

            THIS CERTIFICATE DOES NOT EVIDENCE AN OBLIGATION OF, OR AN INTEREST
IN, THE DEPOSITOR, THE MASTER SERVICER, THE TRUSTEE OR ANY OF THEIR AFFILIATES,
AND IS NOT INSURED OR GUARANTEED BY THE DEPOSITOR, THE MASTER SERVICER, THE
TRUSTEE OR ANY OF THEIR AFFILIATES, OR BY ANY GOVERNMENT AGENCY OR PRIVATE
INSURER.

            DISTRIBUTIONS IN REDUCTION OF THE PRINCIPAL BALANCE OF THIS
CERTIFICATE WILL BE MADE IN THE MANNER DESCRIBED IN THE AGREEMENT. ACCORDINGLY,
THE OUTSTANDING PRINCIPAL BALANCE OF THIS CERTIFICATE AT ANY TIME MAY BE LESS
THAN THE INITIAL PRINCIPAL BALANCE REPRESENTED HEREBY.

Certificate No.                        Cut-Off Date: March 1, 2007

CUSIP No.: 94985R AA0                  First Distribution Date: April 25, 2007

ISIN No.: US94985RAA05                 Denomination: $

Percentage Interest evidenced          Final Scheduled Maturity Date: April 27,
by this Certificate: %                 2037

<PAGE>

            THIS CERTIFIES THAT ___________________________ is the registered
owner of the Percentage Interest evidenced by this Certificate in monthly
distributions to the Holders of the Class A-1 Certificates with respect to a
Trust Estate consisting of a pool of fixed interest rate, monthly pay, first
lien, one- to four-family residential mortgage loans (the "Mortgage Loans"),
other than the Fixed Retained Yield, if any, with respect thereto, formed by
Wells Fargo Asset Securities Corporation (hereinafter called the "Depositor,"
which term includes any successor entity under the Agreement referred to below).
The Trust Estate was created pursuant to a Pooling and Servicing Agreement dated
as of March 28, 2007 (the "Agreement") among the Depositor, Wells Fargo Bank,
N.A., as master servicer (the "Master Servicer") and HSBC Bank USA, National
Association, as trustee (the "Trustee"), a summary of certain of the pertinent
provisions of which is set forth hereinafter. To the extent not defined herein,
the capitalized terms used herein have the meanings ascribed to such terms in
the Agreement. This Certificate is issued under and is subject to the terms,
provisions and conditions of the Agreement, to which Agreement the Holder of
this Certificate by virtue of the acceptance hereof assents and by which such
Holder is bound.

            Pursuant to the terms of the Agreement, a distribution will be made
on the 25th day of each month or, if such 25th day is not a Business Day, the
Business Day immediately following (the "Distribution Date"), commencing on the
first Distribution Date specified above, to the Person in whose name this
Certificate is registered at the close of business on the Record Date, in an
amount equal to the product of the Percentage Interest evidenced by this
Certificate and the Class A Distribution Amount for the Class A-1 Certificates
required to be distributed to Holders of the Class A-1 Certificates on such
Distribution Date, subject to adjustment in certain events as specified in the
Agreement. Distributions in reduction of the Principal Balance of certain
Classes of Class A Certificates may not commence on the first Distribution Date
specified above. Distributions of principal will be allocated among the Classes
of Class A Certificates in accordance with the provisions of the Agreement. The
pass-through rate on the Class A-1 Certificates applicable to each Distribution
Date will be 6.000% per annum. The amount of interest which accrues on this
Certificate in any month will be subject to reduction with respect to any
Non-Supported Interest Shortfall, any Relief Act Shortfall and the interest
portion of certain Realized Losses allocated to the Class A-1 Certificates, as
described in the Agreement.

            Distributions on this Certificate will be made by the Paying Agent
by check mailed to the address of the Person entitled thereto, as such name and
address shall appear on the Certificate Register, unless such Person has
notified the Paying Agent pursuant to the Agreement that such payments are to be
made by wire transfer of immediately available funds. Notwithstanding the above,
the final distribution in reduction of the Principal Balance of this Certificate
will be made after due notice of the pendency of such distribution and only upon
presentation and surrender of this Certificate at the office or agency of the
Paying Agent specified for that purpose in the notice of final distribution.

            Reference is hereby made to the further provisions of this
Certificate set forth on the reverse hereof, which further provisions shall for
all purposes have the same effect as if set forth at this place.

            This Certificate constitutes a "regular interest" in a "real estate
mortgage investment conduit" as those terms are defined in Section 860G(a)(1)
and Section 860D, respectively, of the Internal Revenue Code of 1986, as
amended.

            Unless this Certificate has been countersigned by an authorized
officer of the Authenticating Agent, by manual signature, this Certificate shall
not be entitled to any benefit under the Agreement or be valid for any purpose.

<PAGE>

            IN WITNESS WHEREOF, the Paying Agent has caused this Certificate to
be duly executed as of the date set forth below.


Dated:


                                       Wells Fargo Bank, N.A.,
                                            Paying Agent



                                       By____________________________
                                            Authorized Officer


Countersigned:

Wells Fargo Bank, N.A.,
  Authenticating Agent

By ________________________
   Authorized Officer

<PAGE>

                                   EXHIBIT A-2
                     [FORM OF FACE OF CLASS A-2 CERTIFICATE]


  [UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
   DEPOSITORY TRUST COMPANY TO THE DEPOSITOR OR ITS AGENT FOR REGISTRATION OF
 TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE
       NAME OF CEDE & CO. OR SUCH OTHER NAME AS REQUESTED BY AN AUTHORIZED
 REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY AND ANY PAYMENT IS MADE TO CEDE
 & CO., ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO
  ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN
                                INTEREST HEREIN.]

                        MORTGAGE PASS-THROUGH CERTIFICATE
                            SERIES 2007-4, CLASS A-2

            evidencing an interest in a pool of fixed interest rate,
            monthly pay, first lien, one- to four-family residential
                             mortgage loans sold by

                    WELLS FARGO ASSET SECURITIES CORPORATION
              (Not an interest in or obligation of the Depositor)

            AFTER THE SUBORDINATION DEPLETION DATE, THE PRINCIPAL PORTION OF
REALIZED LOSSES ALLOCATED TO THE CLASS A-5, CLASS A-8, CLASS A-14 AND CLASS A-15
CERTIFICATES WILL BE BORNE BY THE CLASS A-2 CERTIFICATES AS DESCRIBED IN THE
AGREEMENT.

            THIS CERTIFICATE DOES NOT EVIDENCE AN OBLIGATION OF, OR AN INTEREST
IN, THE DEPOSITOR, THE MASTER SERVICER, THE TRUSTEE OR ANY OF THEIR AFFILIATES,
AND IS NOT INSURED OR GUARANTEED BY THE DEPOSITOR, THE MASTER SERVICER, THE
TRUSTEE OR ANY OF THEIR AFFILIATES, OR BY ANY GOVERNMENT AGENCY OR PRIVATE
INSURER.

            DISTRIBUTIONS IN REDUCTION OF THE PRINCIPAL BALANCE OF THIS
CERTIFICATE WILL BE MADE IN THE MANNER DESCRIBED IN THE AGREEMENT. ACCORDINGLY,
THE OUTSTANDING PRINCIPAL BALANCE OF THIS CERTIFICATE AT ANY TIME MAY BE LESS
THAN THE INITIAL PRINCIPAL BALANCE REPRESENTED HEREBY.

Certificate No.                        Cut-Off Date: March 1, 2007

CUSIP No.: 94985R AB8                  First Distribution Date: April 25, 2007

ISIN No.: US94985RAB87                 Denomination: $

Percentage Interest evidenced          Final Scheduled Maturity Date: April 27,
by this Certificate: %                 2037

<PAGE>

            THIS CERTIFIES THAT ___________________________ is the registered
owner of the Percentage Interest evidenced by this Certificate in monthly
distributions to the Holders of the Class A-2 Certificates with respect to a
Trust Estate consisting of a pool of fixed interest rate, monthly pay, first
lien, one- to four-family residential mortgage loans (the "Mortgage Loans"),
other than the Fixed Retained Yield, if any, with respect thereto, formed by
Wells Fargo Asset Securities Corporation (hereinafter called the "Depositor,"
which term includes any successor entity under the Agreement referred to below).
The Trust Estate was created pursuant to a Pooling and Servicing Agreement dated
as of March 28, 2007 (the "Agreement") among the Depositor, Wells Fargo Bank,
N.A., as master servicer (the "Master Servicer") and HSBC Bank USA, National
Association, as trustee (the "Trustee"), a summary of certain of the pertinent
provisions of which is set forth hereinafter. To the extent not defined herein,
the capitalized terms used herein have the meanings ascribed to such terms in
the Agreement. This Certificate is issued under and is subject to the terms,
provisions and conditions of the Agreement, to which Agreement the Holder of
this Certificate by virtue of the acceptance hereof assents and by which such
Holder is bound.

            Pursuant to the terms of the Agreement, a distribution will be made
on the 25th day of each month or, if such 25th day is not a Business Day, the
Business Day immediately following (the "Distribution Date"), commencing on the
first Distribution Date specified above, to the Person in whose name this
Certificate is registered at the close of business on the Record Date, in an
amount equal to the product of the Percentage Interest evidenced by this
Certificate and the Class A Distribution Amount for the Class A-2 Certificates
required to be distributed to Holders of the Class A-2 Certificates on such
Distribution Date, subject to adjustment in certain events as specified in the
Agreement. Distributions in reduction of the Principal Balance of certain
Classes of Class A Certificates may not commence on the first Distribution Date
specified above. Distributions of principal will be allocated among the Classes
of Class A Certificates in accordance with the provisions of the Agreement. The
pass-through rate on the Class A-2 Certificates applicable to each Distribution
Date will be 6.000% per annum. The amount of interest which accrues on this
Certificate in any month will be subject to reduction with respect to any
Non-Supported Interest Shortfall, any Relief Act Shortfall and the interest
portion of certain Realized Losses allocated to the Class A-2 Certificates, as
described in the Agreement.

            Distributions on this Certificate will be made by the Paying Agent
by check mailed to the address of the Person entitled thereto, as such name and
address shall appear on the Certificate Register, unless such Person has
notified the Paying Agent pursuant to the Agreement that such payments are to be
made by wire transfer of immediately available funds. Notwithstanding the above,
the final distribution in reduction of the Principal Balance of this Certificate
will be made after due notice of the pendency of such distribution and only upon
presentation and surrender of this Certificate at the office or agency of the
Paying Agent specified for that purpose in the notice of final distribution.

            Reference is hereby made to the further provisions of this
Certificate set forth on the reverse hereof, which further provisions shall for
all purposes have the same effect as if set forth at this place.

            This Certificate constitutes a "regular interest" in a "real estate
mortgage investment conduit" as those terms are defined in Section 860G(a)(1)
and Section 860D, respectively, of the Internal Revenue Code of 1986, as
amended.

            Unless this Certificate has been countersigned by an authorized
officer of the Authenticating Agent, by manual signature, this Certificate shall
not be entitled to any benefit under the Agreement or be valid for any purpose.

<PAGE>

            IN WITNESS WHEREOF, the Paying Agent has caused this Certificate to
be duly executed as of the date set forth below.

Dated:


                                       Wells Fargo Bank, N.A.,
                                            Paying Agent


                                       By____________________________
                                            Authorized Officer

Countersigned:

Wells Fargo Bank, N.A.,
  Authenticating Agent

By ________________________
   Authorized Officer

<PAGE>

                                   EXHIBIT A-3
                     [FORM OF FACE OF CLASS A-3 CERTIFICATE]

  [UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
   DEPOSITORY TRUST COMPANY TO THE DEPOSITOR OR ITS AGENT FOR REGISTRATION OF
 TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE
       NAME OF CEDE & CO. OR SUCH OTHER NAME AS REQUESTED BY AN AUTHORIZED
 REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY AND ANY PAYMENT IS MADE TO CEDE
 & CO., ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO
  ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN
                                INTEREST HEREIN.]

                        MORTGAGE PASS-THROUGH CERTIFICATE
                            SERIES 2007-4, CLASS A-3

            evidencing an interest in a pool of fixed interest rate,
            monthly pay, first lien, one- to four-family residential
                             mortgage loans sold by

                    WELLS FARGO ASSET SECURITIES CORPORATION
              (Not an interest in or obligation of the Depositor)

            THIS CERTIFICATE DOES NOT EVIDENCE AN OBLIGATION OF, OR AN INTEREST
IN, THE DEPOSITOR, THE MASTER SERVICER, THE TRUSTEE OR ANY OF THEIR AFFILIATES,
AND IS NOT INSURED OR GUARANTEED BY THE DEPOSITOR, THE MASTER SERVICER, THE
TRUSTEE OR ANY OF THEIR AFFILIATES, OR BY ANY GOVERNMENT AGENCY OR PRIVATE
INSURER.

            DISTRIBUTIONS IN REDUCTION OF THE PRINCIPAL BALANCE OF THIS
CERTIFICATE WILL BE MADE IN THE MANNER DESCRIBED IN THE AGREEMENT. ACCORDINGLY,
THE OUTSTANDING PRINCIPAL BALANCE OF THIS CERTIFICATE AT ANY TIME MAY BE LESS
THAN THE INITIAL PRINCIPAL BALANCE REPRESENTED HEREBY.

Certificate No.                        Cut-Off Date: March 1, 2007

CUSIP No.: 94985R AC6                  First Distribution Date: April 25, 2007

ISIN No.: US94985RAC60                 Denomination: $

Percentage Interest evidenced          Final Scheduled Maturity Date: April 27,
by this Certificate: %                 2037


<PAGE>

            THIS CERTIFIES THAT ___________________________ is the registered
owner of the Percentage Interest evidenced by this Certificate in monthly
distributions to the Holders of the Class A-3 Certificates with respect to a
Trust Estate consisting of a pool of fixed interest rate, monthly pay, first
lien, one- to four-family residential mortgage loans (the "Mortgage Loans"),
other than the Fixed Retained Yield, if any, with respect thereto, formed by
Wells Fargo Asset Securities Corporation (hereinafter called the "Depositor,"
which term includes any successor entity under the Agreement referred to below).
The Trust Estate was created pursuant to a Pooling and Servicing Agreement dated
as of March 28, 2007 (the "Agreement") among the Depositor, Wells Fargo Bank,
N.A., as master servicer (the "Master Servicer") and HSBC Bank USA, National
Association, as trustee (the "Trustee"), a summary of certain of the pertinent
provisions of which is set forth hereinafter. To the extent not defined herein,
the capitalized terms used herein have the meanings ascribed to such terms in
the Agreement. This Certificate is issued under and is subject to the terms,
provisions and conditions of the Agreement, to which Agreement the Holder of
this Certificate by virtue of the acceptance hereof assents and by which such
Holder is bound.

            Pursuant to the terms of the Agreement, a distribution will be made
on the 25th day of each month or, if such 25th day is not a Business Day, the
Business Day immediately following (the "Distribution Date"), commencing on the
first Distribution Date specified above, to the Person in whose name this
Certificate is registered at the close of business on the Record Date, in an
amount equal to the product of the Percentage Interest evidenced by this
Certificate and the Class A Distribution Amount for the Class A-3 Certificates
required to be distributed to Holders of the Class A-3 Certificates on such
Distribution Date, subject to adjustment in certain events as specified in the
Agreement. Distributions in reduction of the Principal Balance of certain
Classes of Class A Certificates may not commence on the first Distribution Date
specified above. Distributions of principal will be allocated among the Classes
of Class A Certificates in accordance with the provisions of the Agreement. The
pass-through rate on the Class A-3 Certificates applicable to each Distribution
Date will be 6.000% per annum. The amount of interest which accrues on this
Certificate in any month will be subject to reduction with respect to any
Non-Supported Interest Shortfall, any Relief Act Shortfall and the interest
portion of certain Realized Losses allocated to the Class A-3 Certificates, as
described in the Agreement.

            Distributions on this Certificate will be made by the Paying Agent
by check mailed to the address of the Person entitled thereto, as such name and
address shall appear on the Certificate Register, unless such Person has
notified the Paying Agent pursuant to the Agreement that such payments are to be
made by wire transfer of immediately available funds. Notwithstanding the above,
the final distribution in reduction of the Principal Balance of this Certificate
will be made after due notice of the pendency of such distribution and only upon
presentation and surrender of this Certificate at the office or agency of the
Paying Agent specified for that purpose in the notice of final distribution.

            Reference is hereby made to the further provisions of this
Certificate set forth on the reverse hereof, which further provisions shall for
all purposes have the same effect as if set forth at this place.

            This Certificate constitutes a "regular interest" in a "real estate
mortgage investment conduit" as those terms are defined in Section 860G(a)(1)
and Section 860D, respectively, of the Internal Revenue Code of 1986, as
amended.

            Unless this Certificate has been countersigned by an authorized
officer of the Authenticating Agent, by manual signature, this Certificate shall
not be entitled to any benefit under the Agreement or be valid for any purpose.

<PAGE>

            IN WITNESS WHEREOF, the Paying Agent has caused this Certificate to
be duly executed as of the date set forth below.

Dated:


                                       Wells Fargo Bank, N.A.,
                                            Paying Agent


                                       By____________________________
                                            Authorized Officer

Countersigned:

Wells Fargo Bank, N.A.,
  Authenticating Agent

By ________________________
   Authorized Officer

<PAGE>

                                   EXHIBIT A-4
                     [FORM OF FACE OF CLASS A-4 CERTIFICATE]

  [UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
   DEPOSITORY TRUST COMPANY TO THE DEPOSITOR OR ITS AGENT FOR REGISTRATION OF
 TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE
       NAME OF CEDE & CO. OR SUCH OTHER NAME AS REQUESTED BY AN AUTHORIZED
 REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY AND ANY PAYMENT IS MADE TO CEDE
 & CO., ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO
  ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN
                                INTEREST HEREIN.]

                        MORTGAGE PASS-THROUGH CERTIFICATE
                            SERIES 2007-4, CLASS A-4

            evidencing an interest in a pool of fixed interest rate,
            monthly pay, first lien, one- to four-family residential
                             mortgage loans sold by

                    WELLS FARGO ASSET SECURITIES CORPORATION
              (Not an interest in or obligation of the Depositor)

            THIS CERTIFICATE DOES NOT EVIDENCE AN OBLIGATION OF, OR AN INTEREST
IN, THE DEPOSITOR, THE MASTER SERVICER, THE TRUSTEE OR ANY OF THEIR AFFILIATES,
AND IS NOT INSURED OR GUARANTEED BY THE DEPOSITOR, THE MASTER SERVICER, THE
TRUSTEE OR ANY OF THEIR AFFILIATES, OR BY ANY GOVERNMENT AGENCY OR PRIVATE
INSURER.

            DISTRIBUTIONS IN REDUCTION OF THE PRINCIPAL BALANCE OF THIS
CERTIFICATE WILL BE MADE IN THE MANNER DESCRIBED IN THE AGREEMENT. ACCORDINGLY,
THE OUTSTANDING PRINCIPAL BALANCE OF THIS CERTIFICATE AT ANY TIME MAY BE LESS
THAN THE INITIAL PRINCIPAL BALANCE REPRESENTED HEREBY.

Certificate No.                        Cut-Off Date: March 1, 2007

CUSIP No.: 94985R AD4                  First Distribution Date: April 25, 2007

ISIN No.: US94985RAD44                 Denomination: $

Percentage Interest evidenced          Final Scheduled Maturity Date: April 27,
by this Certificate: %                 2037

<PAGE>

            THIS CERTIFIES THAT ___________________________ is the registered
owner of the Percentage Interest evidenced by this Certificate in monthly
distributions to the Holders of the Class A-4 Certificates with respect to a
Trust Estate consisting of a pool of fixed interest rate, monthly pay, first
lien, one- to four-family residential mortgage loans (the "Mortgage Loans"),
other than the Fixed Retained Yield, if any, with respect thereto, formed by
Wells Fargo Asset Securities Corporation (hereinafter called the "Depositor,"
which term includes any successor entity under the Agreement referred to below).
The Trust Estate was created pursuant to a Pooling and Servicing Agreement dated
as of March 28, 2007 (the "Agreement") among the Depositor, Wells Fargo Bank,
N.A., as master servicer (the "Master Servicer") and HSBC Bank USA, National
Association, as trustee (the "Trustee"), a summary of certain of the pertinent
provisions of which is set forth hereinafter. To the extent not defined herein,
the capitalized terms used herein have the meanings ascribed to such terms in
the Agreement. This Certificate is issued under and is subject to the terms,
provisions and conditions of the Agreement, to which Agreement the Holder of
this Certificate by virtue of the acceptance hereof assents and by which such
Holder is bound.

            Pursuant to the terms of the Agreement, a distribution will be made
on the 25th day of each month or, if such 25th day is not a Business Day, the
Business Day immediately following (the "Distribution Date"), commencing on the
first Distribution Date specified above, to the Person in whose name this
Certificate is registered at the close of business on the Record Date, in an
amount equal to the product of the Percentage Interest evidenced by this
Certificate and the Class A Distribution Amount for the Class A-4 Certificates
required to be distributed to Holders of the Class A-4 Certificates on such
Distribution Date, subject to adjustment in certain events as specified in the
Agreement. Distributions in reduction of the Principal Balance of certain
Classes of Class A Certificates may not commence on the first Distribution Date
specified above. Distributions of principal will be allocated among the Classes
of Class A Certificates in accordance with the provisions of the Agreement. The
pass-through rate on the Class A-4 Certificates applicable to each Distribution
Date will be 6.000% per annum. The amount of interest which accrues on this
Certificate in any month will be subject to reduction with respect to any
Non-Supported Interest Shortfall, any Relief Act Shortfall and the interest
portion of certain Realized Losses allocated to the Class A-4 Certificates, as
described in the Agreement.

            Distributions on this Certificate will be made by the Paying Agent
by check mailed to the address of the Person entitled thereto, as such name and
address shall appear on the Certificate Register, unless such Person has
notified the Paying Agent pursuant to the Agreement that such payments are to be
made by wire transfer of immediately available funds. Notwithstanding the above,
the final distribution in reduction of the Principal Balance of this Certificate
will be made after due notice of the pendency of such distribution and only upon
presentation and surrender of this Certificate at the office or agency of the
Paying Agent specified for that purpose in the notice of final distribution.

            Reference is hereby made to the further provisions of this
Certificate set forth on the reverse hereof, which further provisions shall for
all purposes have the same effect as if set forth at this place.

            This Certificate constitutes a "regular interest" in a "real estate
mortgage investment conduit" as those terms are defined in Section 860G(a)(1)
and Section 860D, respectively, of the Internal Revenue Code of 1986, as
amended.

            Unless this Certificate has been countersigned by an authorized
officer of the Authenticating Agent, by manual signature, this Certificate shall
not be entitled to any benefit under the Agreement or be valid for any purpose.

<PAGE>

            IN WITNESS WHEREOF, the Paying Agent has caused this Certificate to
be duly executed as of the date set forth below.

Dated:


                                       Wells Fargo Bank, N.A.,
                                            Paying Agent


                                       By____________________________
                                            Authorized Officer

Countersigned:

Wells Fargo Bank, N.A.,
  Authenticating Agent

By ________________________
   Authorized Officer

<PAGE>

                                   EXHIBIT A-5
                     [FORM OF FACE OF CLASS A-5 CERTIFICATE]

  [UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
   DEPOSITORY TRUST COMPANY TO THE DEPOSITOR OR ITS AGENT FOR REGISTRATION OF
 TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE
       NAME OF CEDE & CO. OR SUCH OTHER NAME AS REQUESTED BY AN AUTHORIZED
 REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY AND ANY PAYMENT IS MADE TO CEDE
 & CO., ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO
  ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN
                                INTEREST HEREIN.]

                        MORTGAGE PASS-THROUGH CERTIFICATE
                            SERIES 2007-4, CLASS A-5

            evidencing an interest in a pool of fixed interest rate,
            monthly pay, first lien, one- to four-family residential
                             mortgage loans sold by

                    WELLS FARGO ASSET SECURITIES CORPORATION
              (Not an interest in or obligation of the Depositor)

            THIS CERTIFICATE DOES NOT EVIDENCE AN OBLIGATION OF, OR AN INTEREST
IN, THE DEPOSITOR, THE MASTER SERVICER, THE TRUSTEE OR ANY OF THEIR AFFILIATES,
AND IS NOT INSURED OR GUARANTEED BY THE DEPOSITOR, THE MASTER SERVICER, THE
TRUSTEE OR ANY OF THEIR AFFILIATES, OR BY ANY GOVERNMENT AGENCY OR PRIVATE
INSURER.

            DISTRIBUTIONS IN REDUCTION OF THE PRINCIPAL BALANCE OF THIS
CERTIFICATE WILL BE MADE IN THE MANNER DESCRIBED IN THE AGREEMENT. ACCORDINGLY,
THE OUTSTANDING PRINCIPAL BALANCE OF THIS CERTIFICATE AT ANY TIME MAY BE LESS
THAN THE INITIAL PRINCIPAL BALANCE REPRESENTED HEREBY.

Certificate No.                        Cut-Off Date: March 1, 2007

CUSIP No.: 94985R AE2                  First Distribution Date: April 25, 2007

ISIN No.: US94985RAE27                 Denomination: $

Percentage Interest evidenced          Final Scheduled Maturity Date: April 27,
by this Certificate: %                 2037


<PAGE>

            THIS CERTIFIES THAT ___________________________ is the registered
owner of the Percentage Interest evidenced by this Certificate in monthly
distributions to the Holders of the Class A-5 Certificates with respect to a
Trust Estate consisting of a pool of fixed interest rate, monthly pay, first
lien, one- to four-family residential mortgage loans (the "Mortgage Loans"),
other than the Fixed Retained Yield, if any, with respect thereto, formed by
Wells Fargo Asset Securities Corporation (hereinafter called the "Depositor,"
which term includes any successor entity under the Agreement referred to below).
The Trust Estate was created pursuant to a Pooling and Servicing Agreement dated
as of March 28, 2007 (the "Agreement") among the Depositor, Wells Fargo Bank,
N.A., as master servicer (the "Master Servicer") and HSBC Bank USA, National
Association, as trustee (the "Trustee"), a summary of certain of the pertinent
provisions of which is set forth hereinafter. To the extent not defined herein,
the capitalized terms used herein have the meanings ascribed to such terms in
the Agreement. This Certificate is issued under and is subject to the terms,
provisions and conditions of the Agreement, to which Agreement the Holder of
this Certificate by virtue of the acceptance hereof assents and by which such
Holder is bound.

            Pursuant to the terms of the Agreement, a distribution will be made
on the 25th day of each month or, if such 25th day is not a Business Day, the
Business Day immediately following (the "Distribution Date"), commencing on the
first Distribution Date specified above, to the Person in whose name this
Certificate is registered at the close of business on the Record Date, in an
amount equal to the product of the Percentage Interest evidenced by this
Certificate and the Class A Distribution Amount for the Class A-5 Certificates
required to be distributed to Holders of the Class A-5 Certificates on such
Distribution Date, subject to adjustment in certain events as specified in the
Agreement. Distributions in reduction of the Principal Balance of certain
Classes of Class A Certificates may not commence on the first Distribution Date
specified above. Distributions of principal will be allocated among the Classes
of Class A Certificates in accordance with the provisions of the Agreement. The
pass-through rate on the Class A-5 Certificates applicable to each Distribution
Date will be 6.000% per annum. The amount of interest which accrues on this
Certificate in any month will be subject to reduction with respect to any
Non-Supported Interest Shortfall, any Relief Act Shortfall and the interest
portion of certain Realized Losses allocated to the Class A-5 Certificates, as
described in the Agreement.

            Distributions on this Certificate will be made by the Paying Agent
by check mailed to the address of the Person entitled thereto, as such name and
address shall appear on the Certificate Register, unless such Person has
notified the Paying Agent pursuant to the Agreement that such payments are to be
made by wire transfer of immediately available funds. Notwithstanding the above,
the final distribution in reduction of the Principal Balance of this Certificate
will be made after due notice of the pendency of such distribution and only upon
presentation and surrender of this Certificate at the office or agency of the
Paying Agent specified for that purpose in the notice of final distribution.

            Reference is hereby made to the further provisions of this
Certificate set forth on the reverse hereof, which further provisions shall for
all purposes have the same effect as if set forth at this place.

            This Certificate constitutes a "regular interest" in a "real estate
mortgage investment conduit" as those terms are defined in Section 860G(a)(1)
and Section 860D, respectively, of the Internal Revenue Code of 1986, as
amended, and certain other property.

            Unless this Certificate has been countersigned by an authorized
officer of the Authenticating Agent, by manual signature, this Certificate shall
not be entitled to any benefit under the Agreement or be valid for any purpose.

<PAGE>

            IN WITNESS WHEREOF, the Paying Agent has caused this Certificate to
be duly executed as of the date set forth below.

Dated:

                                       Wells Fargo Bank, N.A.,
                                            Paying Agent


                                       By____________________________
                                            Authorized Officer

Countersigned:

Wells Fargo Bank, N.A.,
  Authenticating Agent

By ________________________
   Authorized Officer

<PAGE>

                                   EXHIBIT A-6
                     [FORM OF FACE OF CLASS A-6 CERTIFICATE]

  [UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
   DEPOSITORY TRUST COMPANY TO THE DEPOSITOR OR ITS AGENT FOR REGISTRATION OF
 TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE
       NAME OF CEDE & CO. OR SUCH OTHER NAME AS REQUESTED BY AN AUTHORIZED
 REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY AND ANY PAYMENT IS MADE TO CEDE
 & CO., ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO
  ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN
                                INTEREST HEREIN.]

                        MORTGAGE PASS-THROUGH CERTIFICATE
                            SERIES 2007-4, CLASS A-6

            evidencing an interest in a pool of fixed interest rate,
            monthly pay, first lien, one- to four-family residential
                             mortgage loans sold by

                    WELLS FARGO ASSET SECURITIES CORPORATION
              (Not an interest in or obligation of the Depositor)

            THIS CERTIFICATE DOES NOT EVIDENCE AN OBLIGATION OF, OR AN INTEREST
IN, THE DEPOSITOR, THE MASTER SERVICER, THE TRUSTEE OR ANY OF THEIR AFFILIATES,
AND IS NOT INSURED OR GUARANTEED BY THE DEPOSITOR, THE MASTER SERVICER, THE
TRUSTEE OR ANY OF THEIR AFFILIATES, OR BY ANY GOVERNMENT AGENCY OR PRIVATE
INSURER.

            UNTIL THE APPLICABLE ACCRETION TERMINATION DATE, THE INTEREST THAT
ACCRUES ON THE PRINCIPAL BALANCE OF THIS CERTIFICATE WILL NOT BE PAYABLE.
BECAUSE SUCH UNPAID INTEREST IS ADDED TO THE PRINCIPAL BALANCE OF THIS
CERTIFICATE AND BECAUSE DISTRIBUTIONS IN REDUCTION OF THE PRINCIPAL BALANCE WILL
BE MADE IN THE MANNER DESCRIBED IN THE AGREEMENT, THE OUTSTANDING PRINCIPAL
BALANCE OF THIS CERTIFICATE AT ANY TIME MAY BE MORE OR LESS THAN THE INITIAL
PRINCIPAL BALANCE REPRESENTED HEREBY.

Certificate No.                        Cut-Off Date: March 1, 2007

CUSIP No.: 94985R AF9                  First Distribution Date: April 25, 2007

ISIN No.: US94985RAF91                 Denomination: $

Percentage Interest evidenced          Final Scheduled Maturity Date: April 27,
by this Certificate: %                 2037

<PAGE>

            THIS CERTIFIES THAT ___________________________ is the registered
owner of the Percentage Interest evidenced by this Certificate in monthly
distributions to the Holders of the Class A-6 Certificates with respect to a
Trust Estate consisting of a pool of fixed interest rate, monthly pay, first
lien, one- to four-family residential mortgage loans (the "Mortgage Loans"),
other than the Fixed Retained Yield, if any, with respect thereto, formed by
Wells Fargo Asset Securities Corporation (hereinafter called the "Depositor,"
which term includes any successor entity under the Agreement referred to below).
The Trust Estate was created pursuant to a Pooling and Servicing Agreement dated
as of March 28, 2007 (the "Agreement") among the Depositor, Wells Fargo Bank,
N.A., as master servicer (the "Master Servicer") and HSBC Bank USA, National
Association, as trustee (the "Trustee"), a summary of certain of the pertinent
provisions of which is set forth hereinafter. To the extent not defined herein,
the capitalized terms used herein have the meanings ascribed to such terms in
the Agreement. This Certificate is issued under and is subject to the terms,
provisions and conditions of the Agreement, to which Agreement the Holder of
this Certificate by virtue of the acceptance hereof assents and by which such
Holder is bound.

            Pursuant to the terms of the Agreement, a distribution will be made
on the 25th day of each month or, if such 25th day is not a Business Day, the
Business Day immediately following (the "Distribution Date"), commencing on the
first Distribution Date specified above, to the Person in whose name this
Certificate is registered at the close of business on the Record Date, in an
amount equal to the product of the Percentage Interest evidenced by this
Certificate and the Class A Distribution Amount for the Class A-6 Certificates
required to be distributed to Holders of the Class A-6 Certificates on such
Distribution Date, subject to adjustment in certain events as specified in the
Agreement. Distributions in reduction of the Principal Balance of certain
Classes of Class A Certificates may not commence on the first Distribution Date
specified above. Distributions of principal will be allocated among the Classes
of Class A Certificates in accordance with the provisions of the Agreement.
Prior to the applicable Accretion Termination Date, no distribution of interest
on this Certificate will be made. Prior to the applicable Accretion Termination
Date, interest otherwise available for distribution on this Certificate will be
added to the Principal Balance of the Class A-6 Certificates on each
Distribution Date. The pass-through rate on the Class A-6 Certificates
applicable to each Distribution Date will be 6.000% per annum. The amount of
interest which accrues on this Certificate in any month will be subject to
reduction with respect to any Non-Supported Interest Shortfall, any Relief Act
Shortfall and the interest portion of certain Realized Losses allocated to the
Class A-6 Certificates, as described in the Agreement.

            Distributions on this Certificate will be made by the Paying Agent
by check mailed to the address of the Person entitled thereto, as such name and
address shall appear on the Certificate Register, unless such Person has
notified the Paying Agent pursuant to the Agreement that such payments are to be
made by wire transfer of immediately available funds. Notwithstanding the above,
the final distribution in reduction of the Principal Balance of this Certificate
will be made after due notice of the pendency of such distribution and only upon
presentation and surrender of this Certificate at the office or agency of the
Paying Agent specified for that purpose in the notice of final distribution.

            Reference is hereby made to the further provisions of this
Certificate set forth on the reverse hereof, which further provisions shall for
all purposes have the same effect as if set forth at this place.

            This Certificate constitutes a "regular interest" in a "real estate
mortgage investment conduit" as those terms are defined in Section 860G(a)(1)
and Section 860D, respectively, of the Internal Revenue Code of 1986, as
amended.

            Unless this Certificate has been countersigned by an authorized
officer of the Authenticating Agent, by manual signature, this Certificate shall
not be entitled to any benefit under the Agreement or be valid for any purpose.

<PAGE>

            IN WITNESS WHEREOF, the Paying Agent has caused this Certificate to
be duly executed as of the date set forth below.

Dated:


                                       Wells Fargo Bank, N.A.,
                                            Paying Agent


                                       By____________________________
                                            Authorized Officer

Countersigned:

Wells Fargo Bank, N.A.,
  Authenticating Agent

By ________________________
   Authorized Officer

<PAGE>

                                   EXHIBIT A-7
                     [FORM OF FACE OF CLASS A-7 CERTIFICATE]

  [UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
   DEPOSITORY TRUST COMPANY TO THE DEPOSITOR OR ITS AGENT FOR REGISTRATION OF
 TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE
       NAME OF CEDE & CO. OR SUCH OTHER NAME AS REQUESTED BY AN AUTHORIZED
 REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY AND ANY PAYMENT IS MADE TO CEDE
 & CO., ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO
  ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN
                                INTEREST HEREIN.]

                        MORTGAGE PASS-THROUGH CERTIFICATE
                            SERIES 2007-4, CLASS A-7

            evidencing an interest in a pool of fixed interest rate,
            monthly pay, first lien, one- to four-family residential
                             mortgage loans sold by

                    WELLS FARGO ASSET SECURITIES CORPORATION
              (Not an interest in or obligation of the Depositor)

            THIS CERTIFICATE DOES NOT EVIDENCE AN OBLIGATION OF, OR AN INTEREST
IN, THE DEPOSITOR, THE MASTER SERVICER, THE TRUSTEE OR ANY OF THEIR AFFILIATES,
AND IS NOT INSURED OR GUARANTEED BY THE DEPOSITOR, THE MASTER SERVICER, THE
TRUSTEE OR ANY OF THEIR AFFILIATES, OR BY ANY GOVERNMENT AGENCY OR PRIVATE
INSURER.

            DISTRIBUTIONS IN REDUCTION OF THE PRINCIPAL BALANCE OF THIS
CERTIFICATE WILL BE MADE IN THE MANNER DESCRIBED IN THE AGREEMENT. ACCORDINGLY,
THE OUTSTANDING PRINCIPAL BALANCE OF THIS CERTIFICATE AT ANY TIME MAY BE LESS
THAN THE INITIAL PRINCIPAL BALANCE REPRESENTED HEREBY.

Certificate No.                        Cut-Off Date: March 1, 2007

CUSIP No.: 94985R AG7                  First Distribution Date: April 25, 2007

ISIN No.: US94985RAG74                 Denomination: $

Percentage Interest evidenced          Final Scheduled Maturity Date: April 27,
by this Certificate: %                 2037


<PAGE>

            THIS CERTIFIES THAT ___________________________ is the registered
owner of the Percentage Interest evidenced by this Certificate in monthly
distributions to the Holders of the Class A-7 Certificates with respect to a
Trust Estate consisting of a pool of fixed interest rate, monthly pay, first
lien, one- to four-family residential mortgage loans (the "Mortgage Loans"),
other than the Fixed Retained Yield, if any, with respect thereto, formed by
Wells Fargo Asset Securities Corporation (hereinafter called the "Depositor,"
which term includes any successor entity under the Agreement referred to below).
The Trust Estate was created pursuant to a Pooling and Servicing Agreement dated
as of March 28, 2007 (the "Agreement") among the Depositor, Wells Fargo Bank,
N.A., as master servicer (the "Master Servicer") and HSBC Bank USA, National
Association, as trustee (the "Trustee"), a summary of certain of the pertinent
provisions of which is set forth hereinafter. To the extent not defined herein,
the capitalized terms used herein have the meanings ascribed to such terms in
the Agreement. This Certificate is issued under and is subject to the terms,
provisions and conditions of the Agreement, to which Agreement the Holder of
this Certificate by virtue of the acceptance hereof assents and by which such
Holder is bound.

            Pursuant to the terms of the Agreement, a distribution will be made
on the 25th day of each month or, if such 25th day is not a Business Day, the
Business Day immediately following (the "Distribution Date"), commencing on the
first Distribution Date specified above, to the Person in whose name this
Certificate is registered at the close of business on the Record Date, in an
amount equal to the product of the Percentage Interest evidenced by this
Certificate and the Class A Distribution Amount for the Class A-7 Certificates
required to be distributed to Holders of the Class A-7 Certificates on such
Distribution Date, subject to adjustment in certain events as specified in the
Agreement. Distributions in reduction of the Principal Balance of certain
Classes of Class A Certificates may not commence on the first Distribution Date
specified above. Distributions of principal will be allocated among the Classes
of Class A Certificates in accordance with the provisions of the Agreement. The
pass-through rate on the Class A-7 Certificates applicable to each Distribution
Date will be 5.750% per annum. The amount of interest which accrues on this
Certificate in any month will be subject to reduction with respect to any
Non-Supported Interest Shortfall, any Relief Act Shortfall and the interest
portion of certain Realized Losses allocated to the Class A-7 Certificates, as
described in the Agreement.

            Distributions on this Certificate will be made by the Paying Agent
by check mailed to the address of the Person entitled thereto, as such name and
address shall appear on the Certificate Register, unless such Person has
notified the Paying Agent pursuant to the Agreement that such payments are to be
made by wire transfer of immediately available funds. Notwithstanding the above,
the final distribution in reduction of the Principal Balance of this Certificate
will be made after due notice of the pendency of such distribution and only upon
presentation and surrender of this Certificate at the office or agency of the
Paying Agent specified for that purpose in the notice of final distribution.

            Reference is hereby made to the further provisions of this
Certificate set forth on the reverse hereof, which further provisions shall for
all purposes have the same effect as if set forth at this place.

            This Certificate constitutes a "regular interest" in a "real estate
mortgage investment conduit" as those terms are defined in Section 860G(a)(1)
and Section 860D, respectively, of the Internal Revenue Code of 1986, as
amended.

            Unless this Certificate has been countersigned by an authorized
officer of the Authenticating Agent, by manual signature, this Certificate shall
not be entitled to any benefit under the Agreement or be valid for any purpose.

<PAGE>

            IN WITNESS WHEREOF, the Paying Agent has caused this Certificate to
be duly executed as of the date set forth below.

Dated:


                                       Wells Fargo Bank, N.A.,
                                            Paying Agent


                                       By____________________________
                                            Authorized Officer

Countersigned:

Wells Fargo Bank, N.A.,
  Authenticating Agent

By ________________________
   Authorized Officer

<PAGE>

                                   EXHIBIT A-8
                     [FORM OF FACE OF CLASS A-8 CERTIFICATE]

  [UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
   DEPOSITORY TRUST COMPANY TO THE DEPOSITOR OR ITS AGENT FOR REGISTRATION OF
 TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE
       NAME OF CEDE & CO. OR SUCH OTHER NAME AS REQUESTED BY AN AUTHORIZED
 REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY AND ANY PAYMENT IS MADE TO CEDE
 & CO., ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO
  ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN
                                INTEREST HEREIN.]

                        MORTGAGE PASS-THROUGH CERTIFICATE
                            SERIES 2007-4, CLASS A-8

            evidencing an interest in a pool of fixed interest rate,
            monthly pay, first lien, one- to four-family residential
                             mortgage loans sold by

                    WELLS FARGO ASSET SECURITIES CORPORATION
              (Not an interest in or obligation of the Depositor)

            THIS CERTIFICATE DOES NOT EVIDENCE AN OBLIGATION OF, OR AN INTEREST
IN, THE DEPOSITOR, THE MASTER SERVICER, THE TRUSTEE OR ANY OF THEIR AFFILIATES,
AND IS NOT INSURED OR GUARANTEED BY THE DEPOSITOR, THE MASTER SERVICER, THE
TRUSTEE OR ANY OF THEIR AFFILIATES, OR BY ANY GOVERNMENT AGENCY OR PRIVATE
INSURER.

            DISTRIBUTIONS IN REDUCTION OF THE PRINCIPAL BALANCE OF THIS
CERTIFICATE WILL BE MADE IN THE MANNER DESCRIBED IN THE AGREEMENT. ACCORDINGLY,
THE OUTSTANDING PRINCIPAL BALANCE OF THIS CERTIFICATE AT ANY TIME MAY BE LESS
THAN THE INITIAL PRINCIPAL BALANCE REPRESENTED HEREBY.

Certificate No.                        Cut-Off Date: March 1, 2007

CUSIP No.: 94985R AH5                  First Distribution Date: April 25, 2007

ISIN No.: US94985RAH57                 Denomination: $

Percentage Interest evidenced          Final Scheduled Maturity Date: April 27,
by this Certificate: %                 2037

<PAGE>

            THIS CERTIFIES THAT ___________________________ is the registered
owner of the Percentage Interest evidenced by this Certificate in monthly
distributions to the Holders of the Class A-8 Certificates with respect to a
Trust Estate consisting of a pool of fixed interest rate, monthly pay, first
lien, one- to four-family residential mortgage loans (the "Mortgage Loans"),
other than the Fixed Retained Yield, if any, with respect thereto, formed by
Wells Fargo Asset Securities Corporation (hereinafter called the "Depositor,"
which term includes any successor entity under the Agreement referred to below).
The Trust Estate was created pursuant to a Pooling and Servicing Agreement dated
as of March 28, 2007 (the "Agreement") among the Depositor, Wells Fargo Bank,
N.A., as master servicer (the "Master Servicer") and HSBC Bank USA, National
Association, as trustee (the "Trustee"), a summary of certain of the pertinent
provisions of which is set forth hereinafter. To the extent not defined herein,
the capitalized terms used herein have the meanings ascribed to such terms in
the Agreement. This Certificate is issued under and is subject to the terms,
provisions and conditions of the Agreement, to which Agreement the Holder of
this Certificate by virtue of the acceptance hereof assents and by which such
Holder is bound.

            Pursuant to the terms of the Agreement, a distribution will be made
on the 25th day of each month or, if such 25th day is not a Business Day, the
Business Day immediately following (the "Distribution Date"), commencing on the
first Distribution Date specified above, to the Person in whose name this
Certificate is registered at the close of business on the Record Date, in an
amount equal to the product of the Percentage Interest evidenced by this
Certificate and the Class A Distribution Amount for the Class A-8 Certificates
required to be distributed to Holders of the Class A-8 Certificates on such
Distribution Date, subject to adjustment in certain events as specified in the
Agreement. Distributions in reduction of the Principal Balance of certain
Classes of Class A Certificates may not commence on the first Distribution Date
specified above. Distributions of principal will be allocated among the Classes
of Class A Certificates in accordance with the provisions of the Agreement. The
pass-through rate on the Class A-8 Certificates applicable to each Distribution
Date will be 6.000% per annum. The amount of interest which accrues on this
Certificate in any month will be subject to reduction with respect to any
Non-Supported Interest Shortfall, any Relief Act Shortfall and the interest
portion of certain Realized Losses allocated to the Class A-8 Certificates, as
described in the Agreement.

            Distributions on this Certificate will be made by the Paying Agent
by check mailed to the address of the Person entitled thereto, as such name and
address shall appear on the Certificate Register, unless such Person has
notified the Paying Agent pursuant to the Agreement that such payments are to be
made by wire transfer of immediately available funds. Notwithstanding the above,
the final distribution in reduction of the Principal Balance of this Certificate
will be made after due notice of the pendency of such distribution and only upon
presentation and surrender of this Certificate at the office or agency of the
Paying Agent specified for that purpose in the notice of final distribution.

            Reference is hereby made to the further provisions of this
Certificate set forth on the reverse hereof, which further provisions shall for
all purposes have the same effect as if set forth at this place.

            This Certificate constitutes a "regular interest" in a "real estate
mortgage investment conduit" as those terms are defined in Section 860G(a)(1)
and Section 860D, respectively, of the Internal Revenue Code of 1986, as
amended.

            Unless this Certificate has been countersigned by an authorized
officer of the Authenticating Agent, by manual signature, this Certificate shall
not be entitled to any benefit under the Agreement or be valid for any purpose.

<PAGE>

            IN WITNESS WHEREOF, the Paying Agent has caused this Certificate to
be duly executed as of the date set forth below.

Dated:


                                       Wells Fargo Bank, N.A.,
                                            Paying Agent


                                       By____________________________
                                            Authorized Officer

Countersigned:

Wells Fargo Bank, N.A.,
  Authenticating Agent

                           By ________________________
                               Authorized Officer

<PAGE>

                                   EXHIBIT A-9
                     [FORM OF FACE OF CLASS A-9 CERTIFICATE]

  [UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
   DEPOSITORY TRUST COMPANY TO THE DEPOSITOR OR ITS AGENT FOR REGISTRATION OF
 TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE
       NAME OF CEDE & CO. OR SUCH OTHER NAME AS REQUESTED BY AN AUTHORIZED
 REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY AND ANY PAYMENT IS MADE TO CEDE
 & CO., ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO
  ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN
                                INTEREST HEREIN.]

                        MORTGAGE PASS-THROUGH CERTIFICATE
                            SERIES 2007-4, CLASS A-9

            evidencing an interest in a pool of fixed interest rate,
            monthly pay, first lien, one- to four-family residential
                             mortgage loans sold by

                    WELLS FARGO ASSET SECURITIES CORPORATION
              (Not an interest in or obligation of the Depositor)

            THIS CERTIFICATE DOES NOT EVIDENCE AN OBLIGATION OF, OR AN INTEREST
IN, THE DEPOSITOR, THE MASTER SERVICER, THE TRUSTEE OR ANY OF THEIR AFFILIATES,
AND IS NOT INSURED OR GUARANTEED BY THE DEPOSITOR, THE MASTER SERVICER, THE
TRUSTEE OR ANY OF THEIR AFFILIATES, OR BY ANY GOVERNMENT AGENCY OR PRIVATE
INSURER.

            DISTRIBUTIONS IN REDUCTION OF THE PRINCIPAL BALANCE OF THIS
CERTIFICATE WILL BE MADE IN THE MANNER DESCRIBED IN THE AGREEMENT. ACCORDINGLY,
THE OUTSTANDING PRINCIPAL BALANCE OF THIS CERTIFICATE AT ANY TIME MAY BE LESS
THAN THE INITIAL PRINCIPAL BALANCE REPRESENTED HEREBY.

Certificate No.                        Cut-Off Date: March 1, 2007

CUSIP No.: 94985R AJ1                  First Distribution Date: April 25, 2007

ISIN No.: US94985RAJ14                 Denomination: $

Percentage Interest evidenced          Final Scheduled Maturity Date: April 27,
by this Certificate: %                 2037

<PAGE>

            THIS CERTIFIES THAT ___________________________ is the registered
owner of the Percentage Interest evidenced by this Certificate in monthly
distributions to the Holders of the Class A-9 Certificates with respect to a
Trust Estate consisting of a pool of fixed interest rate, monthly pay, first
lien, one- to four-family residential mortgage loans (the "Mortgage Loans"),
other than the Fixed Retained Yield, if any, with respect thereto, formed by
Wells Fargo Asset Securities Corporation (hereinafter called the "Depositor,"
which term includes any successor entity under the Agreement referred to below).
The Trust Estate was created pursuant to a Pooling and Servicing Agreement dated
as of March 28, 2007 (the "Agreement") among the Depositor, Wells Fargo Bank,
N.A., as master servicer (the "Master Servicer") and HSBC Bank USA, National
Association, as trustee (the "Trustee"), a summary of certain of the pertinent
provisions of which is set forth hereinafter. To the extent not defined herein,
the capitalized terms used herein have the meanings ascribed to such terms in
the Agreement. This Certificate is issued under and is subject to the terms,
provisions and conditions of the Agreement, to which Agreement the Holder of
this Certificate by virtue of the acceptance hereof assents and by which such
Holder is bound.

            Pursuant to the terms of the Agreement, a distribution will be made
on the 25th day of each month or, if such 25th day is not a Business Day, the
Business Day immediately following (the "Distribution Date"), commencing on the
first Distribution Date specified above, to the Person in whose name this
Certificate is registered at the close of business on the Record Date, in an
amount equal to the product of the Percentage Interest evidenced by this
Certificate and the Class A Distribution Amount for the Class A-9 Certificates
required to be distributed to Holders of the Class A-9 Certificates on such
Distribution Date, subject to adjustment in certain events as specified in the
Agreement. Distributions in reduction of the Principal Balance of certain
Classes of Class A Certificates may not commence on the first Distribution Date
specified above. Distributions of principal will be allocated among the Classes
of Class A Certificates in accordance with the provisions of the Agreement. The
pass-through rate on the Class A-9 Certificates applicable to each Distribution
Date will be 6.000% per annum. The amount of interest which accrues on this
Certificate in any month will be subject to reduction with respect to any
Non-Supported Interest Shortfall, any Relief Act Shortfall and the interest
portion of certain Realized Losses allocated to the Class A-9 Certificates, as
described in the Agreement.

            Distributions on this Certificate will be made by the Paying Agent
by check mailed to the address of the Person entitled thereto, as such name and
address shall appear on the Certificate Register, unless such Person has
notified the Paying Agent pursuant to the Agreement that such payments are to be
made by wire transfer of immediately available funds. Notwithstanding the above,
the final distribution in reduction of the Principal Balance of this Certificate
will be made after due notice of the pendency of such distribution and only upon
presentation and surrender of this Certificate at the office or agency of the
Paying Agent specified for that purpose in the notice of final distribution.

            Reference is hereby made to the further provisions of this
Certificate set forth on the reverse hereof, which further provisions shall for
all purposes have the same effect as if set forth at this place.

            This Certificate constitutes a "regular interest" in a "real estate
mortgage investment conduit" as those terms are defined in Section 860G(a)(1)
and Section 860D, respectively, of the Internal Revenue Code of 1986, as
amended.

            Unless this Certificate has been countersigned by an authorized
officer of the Authenticating Agent, by manual signature, this Certificate shall
not be entitled to any benefit under the Agreement or be valid for any purpose.

<PAGE>

            IN WITNESS WHEREOF, the Paying Agent has caused this Certificate to
be duly executed as of the date set forth below.

Dated:


                                       Wells Fargo Bank, N.A.,
                                            Paying Agent


                                       By____________________________
                                            Authorized Officer

Countersigned:

Wells Fargo Bank, N.A.,
  Authenticating Agent

By ________________________
   Authorized Officer

<PAGE>

                                  EXHIBIT A-10
                    [FORM OF FACE OF CLASS A-10 CERTIFICATE]

  [UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
   DEPOSITORY TRUST COMPANY TO THE DEPOSITOR OR ITS AGENT FOR REGISTRATION OF
 TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE
       NAME OF CEDE & CO. OR SUCH OTHER NAME AS REQUESTED BY AN AUTHORIZED
 REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY AND ANY PAYMENT IS MADE TO CEDE
 & CO., ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO
  ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN
                                INTEREST HEREIN.]

                        MORTGAGE PASS-THROUGH CERTIFICATE
                            SERIES 2007-4, CLASS A-10

            evidencing an interest in a pool of fixed interest rate,
            monthly pay, first lien, one- to four-family residential
                             mortgage loans sold by

                    WELLS FARGO ASSET SECURITIES CORPORATION
              (Not an interest in or obligation of the Depositor)

            THIS CERTIFICATE DOES NOT EVIDENCE AN OBLIGATION OF, OR AN INTEREST
IN, THE DEPOSITOR, THE MASTER SERVICER, THE TRUSTEE OR ANY OF THEIR AFFILIATES,
AND IS NOT INSURED OR GUARANTEED BY THE DEPOSITOR, THE MASTER SERVICER, THE
TRUSTEE OR ANY OF THEIR AFFILIATES, OR BY ANY GOVERNMENT AGENCY OR PRIVATE
INSURER.

            UNTIL THE APPLICABLE ACCRETION TERMINATION DATE, THE INTEREST THAT
ACCRUES ON THE PRINCIPAL BALANCE OF THIS CERTIFICATE WILL NOT BE PAYABLE.
BECAUSE SUCH UNPAID INTEREST IS ADDED TO THE PRINCIPAL BALANCE OF THIS
CERTIFICATE AND BECAUSE DISTRIBUTIONS IN REDUCTION OF THE PRINCIPAL BALANCE WILL
BE MADE IN THE MANNER DESCRIBED IN THE AGREEMENT, THE OUTSTANDING PRINCIPAL
BALANCE OF THIS CERTIFICATE AT ANY TIME MAY BE MORE OR LESS THAN THE INITIAL
PRINCIPAL BALANCE REPRESENTED HEREBY.

Certificate No.                        Cut-Off Date: March 1, 2007

CUSIP No.: 94985R AK8                  First Distribution Date: April 25, 2007

ISIN No.: US94985RAK86                 Denomination: $

Percentage Interest evidenced          Final Scheduled Maturity Date: April 27,
by this Certificate: %                 2037

<PAGE>

            THIS CERTIFIES THAT ___________________________ is the registered
owner of the Percentage Interest evidenced by this Certificate in monthly
distributions to the Holders of the Class A-10 Certificates with respect to a
Trust Estate consisting of a pool of fixed interest rate, monthly pay, first
lien, one- to four-family residential mortgage loans (the "Mortgage Loans"),
other than the Fixed Retained Yield, if any, with respect thereto, formed by
Wells Fargo Asset Securities Corporation (hereinafter called the "Depositor,"
which term includes any successor entity under the Agreement referred to below).
The Trust Estate was created pursuant to a Pooling and Servicing Agreement dated
as of March 28, 2007 (the "Agreement") among the Depositor, Wells Fargo Bank,
N.A., as master servicer (the "Master Servicer") and HSBC Bank USA, National
Association, as trustee (the "Trustee"), a summary of certain of the pertinent
provisions of which is set forth hereinafter. To the extent not defined herein,
the capitalized terms used herein have the meanings ascribed to such terms in
the Agreement. This Certificate is issued under and is subject to the terms,
provisions and conditions of the Agreement, to which Agreement the Holder of
this Certificate by virtue of the acceptance hereof assents and by which such
Holder is bound.

            Pursuant to the terms of the Agreement, a distribution will be made
on the 25th day of each month or, if such 25th day is not a Business Day, the
Business Day immediately following (the "Distribution Date"), commencing on the
first Distribution Date specified above, to the Person in whose name this
Certificate is registered at the close of business on the Record Date, in an
amount equal to the product of the Percentage Interest evidenced by this
Certificate and the Class A Distribution Amount for the Class A-10 Certificates
required to be distributed to Holders of the Class A-10 Certificates on such
Distribution Date, subject to adjustment in certain events as specified in the
Agreement. Distributions in reduction of the Principal Balance of certain
Classes of Class A Certificates may not commence on the first Distribution Date
specified above. Distributions of principal will be allocated among the Classes
of Class A Certificates in accordance with the provisions of the Agreement.
Prior to the applicable Accretion Termination Date, no distribution of interest
on this Certificate will be made. Prior to the applicable Accretion Termination
Date, interest otherwise available for distribution on this Certificate will be
added to the Principal Balance of the Class A-10 Certificates on each
Distribution Date. The pass-through rate on the Class A-10 Certificates
applicable to each Distribution Date will be 6.000% per annum. The amount of
interest which accrues on this Certificate in any month will be subject to
reduction with respect to any Non-Supported Interest Shortfall, any Relief Act
Shortfall and the interest portion of certain Realized Losses allocated to the
Class A-10 Certificates, as described in the Agreement.

            Distributions on this Certificate will be made by the Paying Agent
by check mailed to the address of the Person entitled thereto, as such name and
address shall appear on the Certificate Register, unless such Person has
notified the Paying Agent pursuant to the Agreement that such payments are to be
made by wire transfer of immediately available funds. Notwithstanding the above,
the final distribution in reduction of the Principal Balance of this Certificate
will be made after due notice of the pendency of such distribution and only upon
presentation and surrender of this Certificate at the office or agency of the
Paying Agent specified for that purpose in the notice of final distribution.

            Reference is hereby made to the further provisions of this
Certificate set forth on the reverse hereof, which further provisions shall for
all purposes have the same effect as if set forth at this place.

            This Certificate constitutes a "regular interest" in a "real estate
mortgage investment conduit" as those terms are defined in Section 860G(a)(1)
and Section 860D, respectively, of the Internal Revenue Code of 1986, as
amended.

            Unless this Certificate has been countersigned by an authorized
officer of the Authenticating Agent, by manual signature, this Certificate shall
not be entitled to any benefit under the Agreement or be valid for any purpose.

<PAGE>

            IN WITNESS WHEREOF, the Paying Agent has caused this Certificate to
be duly executed as of the date set forth below.

Dated:


                                       Wells Fargo Bank, N.A.,
                                            Paying Agent


                                       By____________________________
                                            Authorized Officer

Countersigned:

Wells Fargo Bank, N.A.,
  Authenticating Agent

By ________________________
   Authorized Officer

<PAGE>

                                  EXHIBIT A-11
                    [FORM OF FACE OF CLASS A-11 CERTIFICATE]

  [UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
   DEPOSITORY TRUST COMPANY TO THE DEPOSITOR OR ITS AGENT FOR REGISTRATION OF
 TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE
       NAME OF CEDE & CO. OR SUCH OTHER NAME AS REQUESTED BY AN AUTHORIZED
 REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY AND ANY PAYMENT IS MADE TO CEDE
 & CO., ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO
  ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN
                                INTEREST HEREIN.]

                        MORTGAGE PASS-THROUGH CERTIFICATE
                            SERIES 2007-4, CLASS A-11

            evidencing an interest in a pool of fixed interest rate,
            monthly pay, first lien, one- to four-family residential
                             mortgage loans sold by

                    WELLS FARGO ASSET SECURITIES CORPORATION
              (Not an interest in or obligation of the Depositor)

            THIS CERTIFICATE DOES NOT EVIDENCE AN OBLIGATION OF, OR AN INTEREST
IN, THE DEPOSITOR, THE MASTER SERVICER, THE TRUSTEE OR ANY OF THEIR AFFILIATES,
AND IS NOT INSURED OR GUARANTEED BY THE DEPOSITOR, THE MASTER SERVICER, THE
TRUSTEE OR ANY OF THEIR AFFILIATES, OR BY ANY GOVERNMENT AGENCY OR PRIVATE
INSURER.

            DISTRIBUTIONS IN REDUCTION OF THE PRINCIPAL BALANCE OF THIS
CERTIFICATE WILL BE MADE IN THE MANNER DESCRIBED IN THE AGREEMENT. ACCORDINGLY,
THE OUTSTANDING PRINCIPAL BALANCE OF THIS CERTIFICATE AT ANY TIME MAY BE LESS
THAN THE INITIAL PRINCIPAL BALANCE REPRESENTED HEREBY.

Certificate No.                        Cut-Off Date: March 1, 2007

CUSIP No.: 94985R AL6                  First Distribution Date: April 25, 2007

ISIN No.: US94985RAL69                 Denomination: $

Percentage Interest evidenced          Final Scheduled Maturity Date: April 27,
by this Certificate: %                 2037

<PAGE>

            THIS CERTIFIES THAT ___________________________ is the registered
owner of the Percentage Interest evidenced by this Certificate in monthly
distributions to the Holders of the Class A-11 Certificates with respect to a
Trust Estate consisting of a pool of fixed interest rate, monthly pay, first
lien, one- to four-family residential mortgage loans (the "Mortgage Loans"),
other than the Fixed Retained Yield, if any, with respect thereto, formed by
Wells Fargo Asset Securities Corporation (hereinafter called the "Depositor,"
which term includes any successor entity under the Agreement referred to below).
The Trust Estate was created pursuant to a Pooling and Servicing Agreement dated
as of March 28, 2007 (the "Agreement") among the Depositor, Wells Fargo Bank,
N.A., as master servicer (the "Master Servicer") and HSBC Bank USA, National
Association, as trustee (the "Trustee"), a summary of certain of the pertinent
provisions of which is set forth hereinafter. To the extent not defined herein,
the capitalized terms used herein have the meanings ascribed to such terms in
the Agreement. This Certificate is issued under and is subject to the terms,
provisions and conditions of the Agreement, to which Agreement the Holder of
this Certificate by virtue of the acceptance hereof assents and by which such
Holder is bound.

            Pursuant to the terms of the Agreement, a distribution will be made
on the 25th day of each month or, if such 25th day is not a Business Day, the
Business Day immediately following (the "Distribution Date"), commencing on the
first Distribution Date specified above, to the Person in whose name this
Certificate is registered at the close of business on the Record Date, in an
amount equal to the product of the Percentage Interest evidenced by this
Certificate and the Class A Distribution Amount for the Class A-11 Certificates
required to be distributed to Holders of the Class A-11 Certificates on such
Distribution Date, subject to adjustment in certain events as specified in the
Agreement. Distributions in reduction of the Principal Balance of certain
Classes of Class A Certificates may not commence on the first Distribution Date
specified above. Distributions of principal will be allocated among the Classes
of Class A Certificates in accordance with the provisions of the Agreement. The
pass-through rate on the Class A-11 Certificates applicable to each Distribution
Date will be 6.500% per annum. The amount of interest which accrues on this
Certificate in any month will be subject to reduction with respect to any
Non-Supported Interest Shortfall, any Relief Act Shortfall and the interest
portion of certain Realized Losses allocated to the Class A-11 Certificates, as
described in the Agreement.

            Distributions on this Certificate will be made by the Paying Agent
by check mailed to the address of the Person entitled thereto, as such name and
address shall appear on the Certificate Register, unless such Person has
notified the Paying Agent pursuant to the Agreement that such payments are to be
made by wire transfer of immediately available funds. Notwithstanding the above,
the final distribution in reduction of the Principal Balance of this Certificate
will be made after due notice of the pendency of such distribution and only upon
presentation and surrender of this Certificate at the office or agency of the
Paying Agent specified for that purpose in the notice of final distribution.

            Reference is hereby made to the further provisions of this
Certificate set forth on the reverse hereof, which further provisions shall for
all purposes have the same effect as if set forth at this place.

            This Certificate constitutes a "regular interest" in a "real estate
mortgage investment conduit" as those terms are defined in Section 860G(a)(1)
and Section 860D, respectively, of the Internal Revenue Code of 1986, as
amended.

            Unless this Certificate has been countersigned by an authorized
officer of the Authenticating Agent, by manual signature, this Certificate shall
not be entitled to any benefit under the Agreement or be valid for any purpose.

<PAGE>

            IN WITNESS WHEREOF, the Paying Agent has caused this Certificate to
be duly executed as of the date set forth below.

Dated:


                                       Wells Fargo Bank, N.A.,
                                            Paying Agent


                                       By____________________________
                                            Authorized Officer

Countersigned:

Wells Fargo Bank, N.A.,
  Authenticating Agent

By ________________________
   Authorized Officer

<PAGE>

                                  EXHIBIT A-12
                    [FORM OF FACE OF CLASS A-12 CERTIFICATE]

  [UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
   DEPOSITORY TRUST COMPANY TO THE DEPOSITOR OR ITS AGENT FOR REGISTRATION OF
 TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE
       NAME OF CEDE & CO. OR SUCH OTHER NAME AS REQUESTED BY AN AUTHORIZED
 REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY AND ANY PAYMENT IS MADE TO CEDE
 & CO., ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO
  ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN
                                INTEREST HEREIN.]

                        MORTGAGE PASS-THROUGH CERTIFICATE
                            SERIES 2007-4, CLASS A-12

            evidencing an interest in a pool of fixed interest rate,
            monthly pay, first lien, one- to four-family residential
                             mortgage loans sold by

                    WELLS FARGO ASSET SECURITIES CORPORATION
              (Not an interest in or obligation of the Depositor)

            AFTER THE SUBORDINATION DEPLETION DATE, THE PRINCIPAL PORTION OF
REALIZED LOSSES ALLOCATED TO THE CLASS A-7 CERTIFICATES WILL BE BORNE BY THE
CLASS A-12 CERTIFICATES AS DESCRIBED IN THE AGREEMENT.

            THIS CERTIFICATE DOES NOT EVIDENCE AN OBLIGATION OF, OR AN INTEREST
IN, THE DEPOSITOR, THE MASTER SERVICER, THE TRUSTEE OR ANY OF THEIR AFFILIATES,
AND IS NOT INSURED OR GUARANTEED BY THE DEPOSITOR, THE MASTER SERVICER, THE
TRUSTEE OR ANY OF THEIR AFFILIATES, OR BY ANY GOVERNMENT AGENCY OR PRIVATE
INSURER.

            DISTRIBUTIONS IN REDUCTION OF THE PRINCIPAL BALANCE OF THIS
CERTIFICATE WILL BE MADE IN THE MANNER DESCRIBED IN THE AGREEMENT. ACCORDINGLY,
THE OUTSTANDING PRINCIPAL BALANCE OF THIS CERTIFICATE AT ANY TIME MAY BE LESS
THAN THE INITIAL PRINCIPAL BALANCE REPRESENTED HEREBY.

Certificate No.                        Cut-Off Date: March 1, 2007

CUSIP No.: 94985R AM4                  First Distribution Date: April 25, 2007

ISIN No.: US94985RAM43                 Denomination: $

Percentage Interest evidenced          Final Scheduled Maturity Date: April 27,
by this Certificate: %                 2037

<PAGE>

            THIS CERTIFIES THAT ___________________________ is the registered
owner of the Percentage Interest evidenced by this Certificate in monthly
distributions to the Holders of the Class A-12 Certificates with respect to a
Trust Estate consisting of a pool of fixed interest rate, monthly pay, first
lien, one- to four-family residential mortgage loans (the "Mortgage Loans"),
other than the Fixed Retained Yield, if any, with respect thereto, formed by
Wells Fargo Asset Securities Corporation (hereinafter called the "Depositor,"
which term includes any successor entity under the Agreement referred to below).
The Trust Estate was created pursuant to a Pooling and Servicing Agreement dated
as of March 28, 2007 (the "Agreement") among the Depositor, Wells Fargo Bank,
N.A., as master servicer (the "Master Servicer") and HSBC Bank USA, National
Association, as trustee (the "Trustee"), a summary of certain of the pertinent
provisions of which is set forth hereinafter. To the extent not defined herein,
the capitalized terms used herein have the meanings ascribed to such terms in
the Agreement. This Certificate is issued under and is subject to the terms,
provisions and conditions of the Agreement, to which Agreement the Holder of
this Certificate by virtue of the acceptance hereof assents and by which such
Holder is bound.

            Pursuant to the terms of the Agreement, a distribution will be made
on the 25th day of each month or, if such 25th day is not a Business Day, the
Business Day immediately following (the "Distribution Date"), commencing on the
first Distribution Date specified above, to the Person in whose name this
Certificate is registered at the close of business on the Record Date, in an
amount equal to the product of the Percentage Interest evidenced by this
Certificate and the Class A Distribution Amount for the Class A-12 Certificates
required to be distributed to Holders of the Class A-12 Certificates on such
Distribution Date, subject to adjustment in certain events as specified in the
Agreement. Distributions in reduction of the Principal Balance of certain
Classes of Class A Certificates may not commence on the first Distribution Date
specified above. Distributions of principal will be allocated among the Classes
of Class A Certificates in accordance with the provisions of the Agreement. The
pass-through rate on the Class A-12 Certificates applicable to each Distribution
Date will be 6.000% per annum. The amount of interest which accrues on this
Certificate in any month will be subject to reduction with respect to any
Non-Supported Interest Shortfall, any Relief Act Shortfall and the interest
portion of certain Realized Losses allocated to the Class A-12 Certificates, as
described in the Agreement.

            Distributions on this Certificate will be made by the Paying Agent
by check mailed to the address of the Person entitled thereto, as such name and
address shall appear on the Certificate Register, unless such Person has
notified the Paying Agent pursuant to the Agreement that such payments are to be
made by wire transfer of immediately available funds. Notwithstanding the above,
the final distribution in reduction of the Principal Balance of this Certificate
will be made after due notice of the pendency of such distribution and only upon
presentation and surrender of this Certificate at the office or agency of the
Paying Agent specified for that purpose in the notice of final distribution.

            Reference is hereby made to the further provisions of this
Certificate set forth on the reverse hereof, which further provisions shall for
all purposes have the same effect as if set forth at this place.

            This Certificate constitutes a "regular interest" in a "real estate
mortgage investment conduit" as those terms are defined in Section 860G(a)(1)
and Section 860D, respectively, of the Internal Revenue Code of 1986, as
amended.

            Unless this Certificate has been countersigned by an authorized
officer of the Authenticating Agent, by manual signature, this Certificate shall
not be entitled to any benefit under the Agreement or be valid for any purpose.

<PAGE>

            IN WITNESS WHEREOF, the Paying Agent has caused this Certificate to
be duly executed as of the date set forth below.

Dated:


                                       Wells Fargo Bank, N.A.,
                                            Paying Agent


                                       By____________________________
                                            Authorized Officer

Countersigned:

Wells Fargo Bank, N.A.,
  Authenticating Agent

By ________________________
   Authorized Officer

<PAGE>

                                  EXHIBIT A-13
                    [FORM OF FACE OF CLASS A-13 CERTIFICATE]

  [UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
   DEPOSITORY TRUST COMPANY TO THE DEPOSITOR OR ITS AGENT FOR REGISTRATION OF
 TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE
       NAME OF CEDE & CO. OR SUCH OTHER NAME AS REQUESTED BY AN AUTHORIZED
 REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY AND ANY PAYMENT IS MADE TO CEDE
 & CO., ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO
  ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN
                                INTEREST HEREIN.]

                        MORTGAGE PASS-THROUGH CERTIFICATE
                            SERIES 2007-4, CLASS A-13

            evidencing an interest in a pool of fixed interest rate,
            monthly pay, first lien, one- to four-family residential
                             mortgage loans sold by

                    WELLS FARGO ASSET SECURITIES CORPORATION
              (Not an interest in or obligation of the Depositor)

            THIS CERTIFICATE DOES NOT EVIDENCE AN OBLIGATION OF, OR AN INTEREST
IN, THE DEPOSITOR, THE MASTER SERVICER, THE TRUSTEE OR ANY OF THEIR AFFILIATES,
AND IS NOT INSURED OR GUARANTEED BY THE DEPOSITOR, THE MASTER SERVICER, THE
TRUSTEE OR ANY OF THEIR AFFILIATES, OR BY ANY GOVERNMENT AGENCY OR PRIVATE
INSURER.

            DISTRIBUTIONS IN REDUCTION OF THE PRINCIPAL BALANCE OF THIS
CERTIFICATE WILL BE MADE IN THE MANNER DESCRIBED IN THE AGREEMENT. ACCORDINGLY,
THE OUTSTANDING PRINCIPAL BALANCE OF THIS CERTIFICATE AT ANY TIME MAY BE LESS
THAN THE INITIAL PRINCIPAL BALANCE REPRESENTED HEREBY.

Certificate No.                        Cut-Off Date: March 1, 2007

CUSIP No.: 94985R AN2                  First Distribution Date: April 25, 2007

ISIN No.: US94985RAN26                 Denomination: $

Percentage Interest evidenced          Final Scheduled Maturity Date: April 27,
by this Certificate: %                 2037

<PAGE>

            THIS CERTIFIES THAT ___________________________ is the registered
owner of the Percentage Interest evidenced by this Certificate in monthly
distributions to the Holders of the Class A-13 Certificates with respect to a
Trust Estate consisting of a pool of fixed interest rate, monthly pay, first
lien, one- to four-family residential mortgage loans (the "Mortgage Loans"),
other than the Fixed Retained Yield, if any, with respect thereto, formed by
Wells Fargo Asset Securities Corporation (hereinafter called the "Depositor,"
which term includes any successor entity under the Agreement referred to below).
The Trust Estate was created pursuant to a Pooling and Servicing Agreement dated
as of March 28, 2007 (the "Agreement") among the Depositor, Wells Fargo Bank,
N.A., as master servicer (the "Master Servicer") and HSBC Bank USA, National
Association, as trustee (the "Trustee"), a summary of certain of the pertinent
provisions of which is set forth hereinafter. To the extent not defined herein,
the capitalized terms used herein have the meanings ascribed to such terms in
the Agreement. This Certificate is issued under and is subject to the terms,
provisions and conditions of the Agreement, to which Agreement the Holder of
this Certificate by virtue of the acceptance hereof assents and by which such
Holder is bound.

            Pursuant to the terms of the Agreement, a distribution will be made
on the 25th day of each month or, if such 25th day is not a Business Day, the
Business Day immediately following (the "Distribution Date"), commencing on the
first Distribution Date specified above, to the Person in whose name this
Certificate is registered at the close of business on the Record Date, in an
amount equal to the product of the Percentage Interest evidenced by this
Certificate and the Class A Distribution Amount for the Class A-13 Certificates
required to be distributed to Holders of the Class A-13 Certificates on such
Distribution Date, subject to adjustment in certain events as specified in the
Agreement. Distributions in reduction of the Principal Balance of certain
Classes of Class A Certificates may not commence on the first Distribution Date
specified above. Distributions of principal will be allocated among the Classes
of Class A Certificates in accordance with the provisions of the Agreement. The
pass-through rate on the Class A-13 Certificates applicable to each Distribution
Date will be 6.000% per annum. The amount of interest which accrues on this
Certificate in any month will be subject to reduction with respect to any
Non-Supported Interest Shortfall, any Relief Act Shortfall and the interest
portion of certain Realized Losses allocated to the Class A-13 Certificates, as
described in the Agreement.

            Distributions on this Certificate will be made by the Paying Agent
by check mailed to the address of the Person entitled thereto, as such name and
address shall appear on the Certificate Register, unless such Person has
notified the Paying Agent pursuant to the Agreement that such payments are to be
made by wire transfer of immediately available funds. Notwithstanding the above,
the final distribution in reduction of the Principal Balance of this Certificate
will be made after due notice of the pendency of such distribution and only upon
presentation and surrender of this Certificate at the office or agency of the
Paying Agent specified for that purpose in the notice of final distribution.

            Reference is hereby made to the further provisions of this
Certificate set forth on the reverse hereof, which further provisions shall for
all purposes have the same effect as if set forth at this place.

            This Certificate constitutes a "regular interest" in a "real estate
mortgage investment conduit" as those terms are defined in Section 860G(a)(1)
and Section 860D, respectively, of the Internal Revenue Code of 1986, as
amended.

            Unless this Certificate has been countersigned by an authorized
officer of the Authenticating Agent, by manual signature, this Certificate shall
not be entitled to any benefit under the Agreement or be valid for any purpose.

<PAGE>

            IN WITNESS WHEREOF, the Paying Agent has caused this Certificate to
be duly executed as of the date set forth below.

Dated:


                                       Wells Fargo Bank, N.A.,
                                            Paying Agent


                                       By____________________________
                                            Authorized Officer

Countersigned:

Wells Fargo Bank, N.A.,
  Authenticating Agent

By ________________________
   Authorized Officer

<PAGE>

                                  EXHIBIT A-14
                    [FORM OF FACE OF CLASS A-14 CERTIFICATE]

  [UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
   DEPOSITORY TRUST COMPANY TO THE DEPOSITOR OR ITS AGENT FOR REGISTRATION OF
 TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE
       NAME OF CEDE & CO. OR SUCH OTHER NAME AS REQUESTED BY AN AUTHORIZED
 REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY AND ANY PAYMENT IS MADE TO CEDE
 & CO., ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO
  ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN
                                INTEREST HEREIN.]

                        MORTGAGE PASS-THROUGH CERTIFICATE
                            SERIES 2007-4, CLASS A-14

            evidencing an interest in a pool of fixed interest rate,
            monthly pay, first lien, one- to four-family residential
                             mortgage loans sold by

                    WELLS FARGO ASSET SECURITIES CORPORATION
              (Not an interest in or obligation of the Depositor)

            THIS CERTIFICATE DOES NOT EVIDENCE AN OBLIGATION OF, OR AN INTEREST
IN, THE DEPOSITOR, THE MASTER SERVICER, THE TRUSTEE OR ANY OF THEIR AFFILIATES,
AND IS NOT INSURED OR GUARANTEED BY THE DEPOSITOR, THE MASTER SERVICER, THE
TRUSTEE OR ANY OF THEIR AFFILIATES, OR BY ANY GOVERNMENT AGENCY OR PRIVATE
INSURER.

            DISTRIBUTIONS IN REDUCTION OF THE PRINCIPAL BALANCE OF THIS
CERTIFICATE WILL BE MADE IN THE MANNER DESCRIBED IN THE AGREEMENT. ACCORDINGLY,
THE OUTSTANDING PRINCIPAL BALANCE OF THIS CERTIFICATE AT ANY TIME MAY BE LESS
THAN THE INITIAL PRINCIPAL BALANCE REPRESENTED HEREBY.

Certificate No.                        Cut-Off Date: March 1, 2007

CUSIP No.: 94985R AP7                  First Distribution Date: April 25, 2007

ISIN No.: US94985RAP73                 Denomination: $

Percentage Interest evidenced          Final Scheduled Maturity Date: April 27,
by this Certificate: %                 2037

<PAGE>

            THIS CERTIFIES THAT ___________________________ is the registered
owner of the Percentage Interest evidenced by this Certificate in monthly
distributions to the Holders of the Class A-14 Certificates with respect to a
Trust Estate consisting of a pool of fixed interest rate, monthly pay, first
lien, one- to four-family residential mortgage loans (the "Mortgage Loans"),
other than the Fixed Retained Yield, if any, with respect thereto, formed by
Wells Fargo Asset Securities Corporation (hereinafter called the "Depositor,"
which term includes any successor entity under the Agreement referred to below).
The Trust Estate was created pursuant to a Pooling and Servicing Agreement dated
as of March 28, 2007 (the "Agreement") among the Depositor, Wells Fargo Bank,
N.A., as master servicer (the "Master Servicer") and HSBC Bank USA, National
Association, as trustee (the "Trustee"), a summary of certain of the pertinent
provisions of which is set forth hereinafter. To the extent not defined herein,
the capitalized terms used herein have the meanings ascribed to such terms in
the Agreement. This Certificate is issued under and is subject to the terms,
provisions and conditions of the Agreement, to which Agreement the Holder of
this Certificate by virtue of the acceptance hereof assents and by which such
Holder is bound.

            Pursuant to the terms of the Agreement, a distribution will be made
on the 25th day of each month or, if such 25th day is not a Business Day, the
Business Day immediately following (the "Distribution Date"), commencing on the
first Distribution Date specified above, to the Person in whose name this
Certificate is registered at the close of business on the Record Date, in an
amount equal to the product of the Percentage Interest evidenced by this
Certificate and the Class A Distribution Amount for the Class A-14 Certificates
required to be distributed to Holders of the Class A-14 Certificates on such
Distribution Date, subject to adjustment in certain events as specified in the
Agreement. Distributions in reduction of the Principal Balance of certain
Classes of Class A Certificates may not commence on the first Distribution Date
specified above. Distributions of principal will be allocated among the Classes
of Class A Certificates in accordance with the provisions of the Agreement. The
pass-through rate on the Class A-14 Certificates applicable to each Distribution
Date will be 6.000% per annum. The amount of interest which accrues on this
Certificate in any month will be subject to reduction with respect to any
Non-Supported Interest Shortfall, any Relief Act Shortfall and the interest
portion of certain Realized Losses allocated to the Class A-14 Certificates, as
described in the Agreement.

            Distributions on this Certificate will be made by the Paying Agent
by check mailed to the address of the Person entitled thereto, as such name and
address shall appear on the Certificate Register, unless such Person has
notified the Paying Agent pursuant to the Agreement that such payments are to be
made by wire transfer of immediately available funds. Notwithstanding the above,
the final distribution in reduction of the Principal Balance of this Certificate
will be made after due notice of the pendency of such distribution and only upon
presentation and surrender of this Certificate at the office or agency of the
Paying Agent specified for that purpose in the notice of final distribution.

            Reference is hereby made to the further provisions of this
Certificate set forth on the reverse hereof, which further provisions shall for
all purposes have the same effect as if set forth at this place.

            This Certificate constitutes a "regular interest" in a "real estate
mortgage investment conduit" as those terms are defined in Section 860G(a)(1)
and Section 860D, respectively, of the Internal Revenue Code of 1986, as
amended.

            Unless this Certificate has been countersigned by an authorized
officer of the Authenticating Agent, by manual signature, this Certificate shall
not be entitled to any benefit under the Agreement or be valid for any purpose.

<PAGE>

            IN WITNESS WHEREOF, the Paying Agent has caused this Certificate to
be duly executed as of the date set forth below.

Dated:


                                       Wells Fargo Bank, N.A.,
                                            Paying Agent


                                       By____________________________
                                            Authorized Officer

Countersigned:

Wells Fargo Bank, N.A.,
  Authenticating Agent

By ________________________
   Authorized Officer

<PAGE>

                                  EXHIBIT A-15
                    [FORM OF FACE OF CLASS A-15 CERTIFICATE]

  [UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
   DEPOSITORY TRUST COMPANY TO THE DEPOSITOR OR ITS AGENT FOR REGISTRATION OF
 TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE
       NAME OF CEDE & CO. OR SUCH OTHER NAME AS REQUESTED BY AN AUTHORIZED
 REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY AND ANY PAYMENT IS MADE TO CEDE
 & CO., ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO
  ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN
                                INTEREST HEREIN.]

                        MORTGAGE PASS-THROUGH CERTIFICATE
                            SERIES 2007-4, CLASS A-15

            evidencing an interest in a pool of fixed interest rate,
            monthly pay, first lien, one- to four-family residential
                             mortgage loans sold by

                    WELLS FARGO ASSET SECURITIES CORPORATION
              (Not an interest in or obligation of the Depositor)

            THIS CERTIFICATE DOES NOT EVIDENCE AN OBLIGATION OF, OR AN INTEREST
IN, THE DEPOSITOR, THE MASTER SERVICER, THE TRUSTEE OR ANY OF THEIR AFFILIATES,
AND IS NOT INSURED OR GUARANTEED BY THE DEPOSITOR, THE MASTER SERVICER, THE
TRUSTEE OR ANY OF THEIR AFFILIATES, OR BY ANY GOVERNMENT AGENCY OR PRIVATE
INSURER.

            DISTRIBUTIONS IN REDUCTION OF THE PRINCIPAL BALANCE OF THIS
CERTIFICATE WILL BE MADE IN THE MANNER DESCRIBED IN THE AGREEMENT. ACCORDINGLY,
THE OUTSTANDING PRINCIPAL BALANCE OF THIS CERTIFICATE AT ANY TIME MAY BE LESS
THAN THE INITIAL PRINCIPAL BALANCE REPRESENTED HEREBY.

Certificate No.                        Cut-Off Date: March 1, 2007

CUSIP No.: 94985R AQ5                  First Distribution Date: April 25, 2007

ISIN No.: US94985RAQ56                 Denomination: $

Percentage Interest evidenced          Final Scheduled Maturity Date: April 27,
by this Certificate: %                 2037

<PAGE>

            THIS CERTIFIES THAT ___________________________ is the registered
owner of the Percentage Interest evidenced by this Certificate in monthly
distributions to the Holders of the Class A-15 Certificates with respect to a
Trust Estate consisting of a pool of fixed interest rate, monthly pay, first
lien, one- to four-family residential mortgage loans (the "Mortgage Loans"),
other than the Fixed Retained Yield, if any, with respect thereto, formed by
Wells Fargo Asset Securities Corporation (hereinafter called the "Depositor,"
which term includes any successor entity under the Agreement referred to below).
The Trust Estate was created pursuant to a Pooling and Servicing Agreement dated
as of March 28, 2007 (the "Agreement") among the Depositor, Wells Fargo Bank,
N.A., as master servicer (the "Master Servicer") and HSBC Bank USA, National
Association, as trustee (the "Trustee"), a summary of certain of the pertinent
provisions of which is set forth hereinafter. To the extent not defined herein,
the capitalized terms used herein have the meanings ascribed to such terms in
the Agreement. This Certificate is issued under and is subject to the terms,
provisions and conditions of the Agreement, to which Agreement the Holder of
this Certificate by virtue of the acceptance hereof assents and by which such
Holder is bound.

            Pursuant to the terms of the Agreement, a distribution will be made
on the 25th day of each month or, if such 25th day is not a Business Day, the
Business Day immediately following (the "Distribution Date"), commencing on the
first Distribution Date specified above, to the Person in whose name this
Certificate is registered at the close of business on the Record Date, in an
amount equal to the product of the Percentage Interest evidenced by this
Certificate and the Class A Distribution Amount for the Class A-15 Certificates
required to be distributed to Holders of the Class A-15 Certificates on such
Distribution Date, subject to adjustment in certain events as specified in the
Agreement. Distributions in reduction of the Principal Balance of certain
Classes of Class A Certificates may not commence on the first Distribution Date
specified above. Distributions of principal will be allocated among the Classes
of Class A Certificates in accordance with the provisions of the Agreement. The
pass-through rate on the Class A-15 Certificates applicable to each Distribution
Date will be 6.000% per annum. The amount of interest which accrues on this
Certificate in any month will be subject to reduction with respect to any
Non-Supported Interest Shortfall, any Relief Act Shortfall and the interest
portion of certain Realized Losses allocated to the Class A-15 Certificates, as
described in the Agreement.

            Distributions on this Certificate will be made by the Paying Agent
by check mailed to the address of the Person entitled thereto, as such name and
address shall appear on the Certificate Register, unless such Person has
notified the Paying Agent pursuant to the Agreement that such payments are to be
made by wire transfer of immediately available funds. Notwithstanding the above,
the final distribution in reduction of the Principal Balance of this Certificate
will be made after due notice of the pendency of such distribution and only upon
presentation and surrender of this Certificate at the office or agency of the
Paying Agent specified for that purpose in the notice of final distribution.

            Reference is hereby made to the further provisions of this
Certificate set forth on the reverse hereof, which further provisions shall for
all purposes have the same effect as if set forth at this place.

            This Certificate constitutes a "regular interest" in a "real estate
mortgage investment conduit" as those terms are defined in Section 860G(a)(1)
and Section 860D, respectively, of the Internal Revenue Code of 1986, as
amended.

            Unless this Certificate has been countersigned by an authorized
officer of the Authenticating Agent, by manual signature, this Certificate shall
not be entitled to any benefit under the Agreement or be valid for any purpose.

<PAGE>

            IN WITNESS WHEREOF, the Paying Agent has caused this Certificate to
be duly executed as of the date set forth below.

Dated:


                                       Wells Fargo Bank, N.A.,
                                            Paying Agent


                                       By____________________________
                                            Authorized Officer

Countersigned:

Wells Fargo Bank, N.A.,
  Authenticating Agent

By ________________________
   Authorized Officer

<PAGE>

                                  EXHIBIT A-16
                    [FORM OF FACE OF CLASS A-16 CERTIFICATE]

  [UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
   DEPOSITORY TRUST COMPANY TO THE DEPOSITOR OR ITS AGENT FOR REGISTRATION OF
 TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE
       NAME OF CEDE & CO. OR SUCH OTHER NAME AS REQUESTED BY AN AUTHORIZED
 REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY AND ANY PAYMENT IS MADE TO CEDE
 & CO., ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO
  ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN
                                INTEREST HEREIN.]

                        MORTGAGE PASS-THROUGH CERTIFICATE
                            SERIES 2007-4, CLASS A-16

            evidencing an interest in a pool of fixed interest rate,
            monthly pay, first lien, one- to four-family residential
                             mortgage loans sold by

                    WELLS FARGO ASSET SECURITIES CORPORATION
              (Not an interest in or obligation of the Depositor)

            THIS CERTIFICATE DOES NOT EVIDENCE AN OBLIGATION OF, OR AN INTEREST
IN, THE DEPOSITOR, THE MASTER SERVICER, THE TRUSTEE OR ANY OF THEIR AFFILIATES,
AND IS NOT INSURED OR GUARANTEED BY THE DEPOSITOR, THE MASTER SERVICER, THE
TRUSTEE OR ANY OF THEIR AFFILIATES, OR BY ANY GOVERNMENT AGENCY OR PRIVATE
INSURER.

            DISTRIBUTIONS IN REDUCTION OF THE PRINCIPAL BALANCE OF THIS
CERTIFICATE WILL BE MADE IN THE MANNER DESCRIBED IN THE AGREEMENT. ACCORDINGLY,
THE OUTSTANDING PRINCIPAL BALANCE OF THIS CERTIFICATE AT ANY TIME MAY BE LESS
THAN THE INITIAL PRINCIPAL BALANCE REPRESENTED HEREBY.

Certificate No.                        Cut-Off Date: March 1, 2007

CUSIP No.: 94985R AR3                  First Distribution Date: April 25, 2007

ISIN No.: US94985RAR30                 Denomination: $

Percentage Interest evidenced          Final Scheduled Maturity Date: April 27,
by this Certificate: %                 2037

<PAGE>

            THIS CERTIFIES THAT ___________________________ is the registered
owner of the Percentage Interest evidenced by this Certificate in monthly
distributions to the Holders of the Class A-16 Certificates with respect to a
Trust Estate consisting of a pool of fixed interest rate, monthly pay, first
lien, one- to four-family residential mortgage loans (the "Mortgage Loans"),
other than the Fixed Retained Yield, if any, with respect thereto, formed by
Wells Fargo Asset Securities Corporation (hereinafter called the "Depositor,"
which term includes any successor entity under the Agreement referred to below).
The Trust Estate was created pursuant to a Pooling and Servicing Agreement dated
as of March 28, 2007 (the "Agreement") among the Depositor, Wells Fargo Bank,
N.A., as master servicer (the "Master Servicer") and HSBC Bank USA, National
Association, as trustee (the "Trustee"), a summary of certain of the pertinent
provisions of which is set forth hereinafter. To the extent not defined herein,
the capitalized terms used herein have the meanings ascribed to such terms in
the Agreement. This Certificate is issued under and is subject to the terms,
provisions and conditions of the Agreement, to which Agreement the Holder of
this Certificate by virtue of the acceptance hereof assents and by which such
Holder is bound.

            Pursuant to the terms of the Agreement, a distribution will be made
on the 25th day of each month or, if such 25th day is not a Business Day, the
Business Day immediately following (the "Distribution Date"), commencing on the
first Distribution Date specified above, to the Person in whose name this
Certificate is registered at the close of business on the Record Date, in an
amount equal to the product of the Percentage Interest evidenced by this
Certificate and the Class A Distribution Amount for the Class A-16 Certificates
required to be distributed to Holders of the Class A-16 Certificates on such
Distribution Date, subject to adjustment in certain events as specified in the
Agreement. Distributions in reduction of the Principal Balance of certain
Classes of Class A Certificates may not commence on the first Distribution Date
specified above. Distributions of principal will be allocated among the Classes
of Class A Certificates in accordance with the provisions of the Agreement. The
pass-through rate on the Class A-16 Certificates applicable to each Distribution
Date will be 5.500% per annum. The amount of interest which accrues on this
Certificate in any month will be subject to reduction with respect to any
Non-Supported Interest Shortfall, any Relief Act Shortfall and the interest
portion of certain Realized Losses allocated to the Class A-16 Certificates, as
described in the Agreement.

            Distributions on this Certificate will be made by the Paying Agent
by check mailed to the address of the Person entitled thereto, as such name and
address shall appear on the Certificate Register, unless such Person has
notified the Paying Agent pursuant to the Agreement that such payments are to be
made by wire transfer of immediately available funds. Notwithstanding the above,
the final distribution in reduction of the Principal Balance of this Certificate
will be made after due notice of the pendency of such distribution and only upon
presentation and surrender of this Certificate at the office or agency of the
Paying Agent specified for that purpose in the notice of final distribution.

            Reference is hereby made to the further provisions of this
Certificate set forth on the reverse hereof, which further provisions shall for
all purposes have the same effect as if set forth at this place.

            This Certificate constitutes a "regular interest" in a "real estate
mortgage investment conduit" as those terms are defined in Section 860G(a)(1)
and Section 860D, respectively, of the Internal Revenue Code of 1986, as
amended.

            Unless this Certificate has been countersigned by an authorized
officer of the Authenticating Agent, by manual signature, this Certificate shall
not be entitled to any benefit under the Agreement or be valid for any purpose.

<PAGE>

            IN WITNESS WHEREOF, the Paying Agent has caused this Certificate to
be duly executed as of the date set forth below.

Dated:


                                       Wells Fargo Bank, N.A.,
                                            Paying Agent


                                       By____________________________
                                            Authorized Officer

Countersigned:

Wells Fargo Bank, N.A.,
  Authenticating Agent

By ________________________
   Authorized Officer

<PAGE>

                                  EXHIBIT A-17
                    [FORM OF FACE OF CLASS A-17 CERTIFICATE]

  [UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
   DEPOSITORY TRUST COMPANY TO THE DEPOSITOR OR ITS AGENT FOR REGISTRATION OF
 TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE
       NAME OF CEDE & CO. OR SUCH OTHER NAME AS REQUESTED BY AN AUTHORIZED
 REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY AND ANY PAYMENT IS MADE TO CEDE
 & CO., ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO
  ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN
                                INTEREST HEREIN.]

                        MORTGAGE PASS-THROUGH CERTIFICATE
                            SERIES 2007-4, CLASS A-17

            evidencing an interest in a pool of fixed interest rate,
            monthly pay, first lien, one- to four-family residential
                             mortgage loans sold by

                    WELLS FARGO ASSET SECURITIES CORPORATION
              (Not an interest in or obligation of the Depositor)

            THIS CERTIFICATE DOES NOT EVIDENCE AN OBLIGATION OF, OR AN INTEREST
IN, THE DEPOSITOR, THE MASTER SERVICER, THE TRUSTEE OR ANY OF THEIR AFFILIATES,
AND IS NOT INSURED OR GUARANTEED BY THE DEPOSITOR, THE MASTER SERVICER, THE
TRUSTEE OR ANY OF THEIR AFFILIATES, OR BY ANY GOVERNMENT AGENCY OR PRIVATE
INSURER.

            DISTRIBUTIONS IN REDUCTION OF THE PRINCIPAL BALANCE OF THIS
CERTIFICATE WILL BE MADE IN THE MANNER DESCRIBED IN THE AGREEMENT. ACCORDINGLY,
THE OUTSTANDING PRINCIPAL BALANCE OF THIS CERTIFICATE AT ANY TIME MAY BE LESS
THAN THE INITIAL PRINCIPAL BALANCE REPRESENTED HEREBY.

Certificate No.                        Cut-Off Date: March 1, 2007

CUSIP No.: 94985R AS1                  First Distribution Date: April 25, 2007

ISIN No.: US94985RAS13                 Denomination: $

Percentage Interest evidenced          Final Scheduled Maturity Date: April 27,
by this Certificate: %                 2037

<PAGE>

            THIS CERTIFIES THAT ___________________________ is the registered
owner of the Percentage Interest evidenced by this Certificate in monthly
distributions to the Holders of the Class A-17 Certificates with respect to a
Trust Estate consisting of a pool of fixed interest rate, monthly pay, first
lien, one- to four-family residential mortgage loans (the "Mortgage Loans"),
other than the Fixed Retained Yield, if any, with respect thereto, formed by
Wells Fargo Asset Securities Corporation (hereinafter called the "Depositor,"
which term includes any successor entity under the Agreement referred to below).
The Trust Estate was created pursuant to a Pooling and Servicing Agreement dated
as of March 28, 2007 (the "Agreement") among the Depositor, Wells Fargo Bank,
N.A., as master servicer (the "Master Servicer") and HSBC Bank USA, National
Association, as trustee (the "Trustee"), a summary of certain of the pertinent
provisions of which is set forth hereinafter. To the extent not defined herein,
the capitalized terms used herein have the meanings ascribed to such terms in
the Agreement. This Certificate is issued under and is subject to the terms,
provisions and conditions of the Agreement, to which Agreement the Holder of
this Certificate by virtue of the acceptance hereof assents and by which such
Holder is bound.

            Pursuant to the terms of the Agreement, a distribution will be made
on the 25th day of each month or, if such 25th day is not a Business Day, the
Business Day immediately following (the "Distribution Date"), commencing on the
first Distribution Date specified above, to the Person in whose name this
Certificate is registered at the close of business on the Record Date, in an
amount equal to the product of the Percentage Interest evidenced by this
Certificate and the Class A Distribution Amount for the Class A-17 Certificates
required to be distributed to Holders of the Class A-17 Certificates on such
Distribution Date, subject to adjustment in certain events as specified in the
Agreement. Distributions in reduction of the Principal Balance of certain
Classes of Class A Certificates may not commence on the first Distribution Date
specified above. Distributions of principal will be allocated among the Classes
of Class A Certificates in accordance with the provisions of the Agreement. The
pass-through rate on the Class A-17 Certificates applicable to each Distribution
Date will be 5.500% per annum. The amount of interest which accrues on this
Certificate in any month will be subject to reduction with respect to any
Non-Supported Interest Shortfall, any Relief Act Shortfall and the interest
portion of certain Realized Losses allocated to the Class A-17 Certificates, as
described in the Agreement.

            Distributions on this Certificate will be made by the Paying Agent
by check mailed to the address of the Person entitled thereto, as such name and
address shall appear on the Certificate Register, unless such Person has
notified the Paying Agent pursuant to the Agreement that such payments are to be
made by wire transfer of immediately available funds. Notwithstanding the above,
the final distribution in reduction of the Principal Balance of this Certificate
will be made after due notice of the pendency of such distribution and only upon
presentation and surrender of this Certificate at the office or agency of the
Paying Agent specified for that purpose in the notice of final distribution.

            Reference is hereby made to the further provisions of this
Certificate set forth on the reverse hereof, which further provisions shall for
all purposes have the same effect as if set forth at this place.

            This Certificate constitutes a "regular interest" in a "real estate
mortgage investment conduit" as those terms are defined in Section 860G(a)(1)
and Section 860D, respectively, of the Internal Revenue Code of 1986, as
amended.

            Unless this Certificate has been countersigned by an authorized
officer of the Authenticating Agent, by manual signature, this Certificate shall
not be entitled to any benefit under the Agreement or be valid for any purpose.

<PAGE>

            IN WITNESS WHEREOF, the Paying Agent has caused this Certificate to
be duly executed as of the date set forth below.

Dated:


                                       Wells Fargo Bank, N.A.,
                                            Paying Agent


                                       By____________________________
                                            Authorized Officer

Countersigned:

Wells Fargo Bank, N.A.,
  Authenticating Agent

By ________________________
   Authorized Officer

<PAGE>

                                  EXHIBIT A-18
                    [FORM OF FACE OF CLASS A-18 CERTIFICATE]

  [UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
   DEPOSITORY TRUST COMPANY TO THE DEPOSITOR OR ITS AGENT FOR REGISTRATION OF
 TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE
       NAME OF CEDE & CO. OR SUCH OTHER NAME AS REQUESTED BY AN AUTHORIZED
 REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY AND ANY PAYMENT IS MADE TO CEDE
 & CO., ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO
  ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN
                                INTEREST HEREIN.]

                        MORTGAGE PASS-THROUGH CERTIFICATE
                            SERIES 2007-4, CLASS A-18

            evidencing an interest in a pool of fixed interest rate,
            monthly pay, first lien, one- to four-family residential
                             mortgage loans sold by

                    WELLS FARGO ASSET SECURITIES CORPORATION
              (Not an interest in or obligation of the Depositor)

            THIS CERTIFICATE DOES NOT EVIDENCE AN OBLIGATION OF, OR AN INTEREST
IN, THE DEPOSITOR, THE MASTER SERVICER, THE TRUSTEE OR ANY OF THEIR AFFILIATES,
AND IS NOT INSURED OR GUARANTEED BY THE DEPOSITOR, THE MASTER SERVICER, THE
TRUSTEE OR ANY OF THEIR AFFILIATES, OR BY ANY GOVERNMENT AGENCY OR PRIVATE
INSURER.

            DISTRIBUTIONS IN REDUCTION OF THE PRINCIPAL BALANCE OF THIS
CERTIFICATE WILL BE MADE IN THE MANNER DESCRIBED IN THE AGREEMENT. ACCORDINGLY,
THE OUTSTANDING PRINCIPAL BALANCE OF THIS CERTIFICATE AT ANY TIME MAY BE LESS
THAN THE INITIAL PRINCIPAL BALANCE REPRESENTED HEREBY.

Certificate No.                        Cut-Off Date: March 1, 2007

CUSIP No.: 94985R AT9                  First Distribution Date: April 25, 2007

ISIN No.: US94985RAT95                 Denomination: $

Percentage Interest evidenced          Final Scheduled Maturity Date: April 27,
by this Certificate: %                 2037

<PAGE>

            THIS CERTIFIES THAT ___________________________ is the registered
owner of the Percentage Interest evidenced by this Certificate in monthly
distributions to the Holders of the Class A-18 Certificates with respect to a
Trust Estate consisting of a pool of fixed interest rate, monthly pay, first
lien, one- to four-family residential mortgage loans (the "Mortgage Loans"),
other than the Fixed Retained Yield, if any, with respect thereto, formed by
Wells Fargo Asset Securities Corporation (hereinafter called the "Depositor,"
which term includes any successor entity under the Agreement referred to below).
The Trust Estate was created pursuant to a Pooling and Servicing Agreement dated
as of March 28, 2007 (the "Agreement") among the Depositor, Wells Fargo Bank,
N.A., as master servicer (the "Master Servicer") and HSBC Bank USA, National
Association, as trustee (the "Trustee"), a summary of certain of the pertinent
provisions of which is set forth hereinafter. To the extent not defined herein,
the capitalized terms used herein have the meanings ascribed to such terms in
the Agreement. This Certificate is issued under and is subject to the terms,
provisions and conditions of the Agreement, to which Agreement the Holder of
this Certificate by virtue of the acceptance hereof assents and by which such
Holder is bound.

            Pursuant to the terms of the Agreement, a distribution will be made
on the 25th day of each month or, if such 25th day is not a Business Day, the
Business Day immediately following (the "Distribution Date"), commencing on the
first Distribution Date specified above, to the Person in whose name this
Certificate is registered at the close of business on the Record Date, in an
amount equal to the product of the Percentage Interest evidenced by this
Certificate and the Class A Distribution Amount for the Class A-18 Certificates
required to be distributed to Holders of the Class A-18 Certificates on such
Distribution Date, subject to adjustment in certain events as specified in the
Agreement. Distributions in reduction of the Principal Balance of certain
Classes of Class A Certificates may not commence on the first Distribution Date
specified above. Distributions of principal will be allocated among the Classes
of Class A Certificates in accordance with the provisions of the Agreement. The
pass-through rate on the Class A-18 Certificates applicable to each Distribution
Date will be 5.500% per annum. The amount of interest which accrues on this
Certificate in any month will be subject to reduction with respect to any
Non-Supported Interest Shortfall, any Relief Act Shortfall and the interest
portion of certain Realized Losses allocated to the Class A-18 Certificates, as
described in the Agreement.

            Distributions on this Certificate will be made by the Paying Agent
by check mailed to the address of the Person entitled thereto, as such name and
address shall appear on the Certificate Register, unless such Person has
notified the Paying Agent pursuant to the Agreement that such payments are to be
made by wire transfer of immediately available funds. Notwithstanding the above,
the final distribution in reduction of the Principal Balance of this Certificate
will be made after due notice of the pendency of such distribution and only upon
presentation and surrender of this Certificate at the office or agency of the
Paying Agent specified for that purpose in the notice of final distribution.

            Reference is hereby made to the further provisions of this
Certificate set forth on the reverse hereof, which further provisions shall for
all purposes have the same effect as if set forth at this place.

            This Certificate constitutes a "regular interest" in a "real estate
mortgage investment conduit" as those terms are defined in Section 860G(a)(1)
and Section 860D, respectively, of the Internal Revenue Code of 1986, as
amended.

            Unless this Certificate has been countersigned by an authorized
officer of the Authenticating Agent, by manual signature, this Certificate shall
not be entitled to any benefit under the Agreement or be valid for any purpose.

<PAGE>

            IN WITNESS WHEREOF, the Paying Agent has caused this Certificate to
be duly executed as of the date set forth below.

Dated:


                                       Wells Fargo Bank, N.A.,
                                            Paying Agent


                                       By____________________________
                                            Authorized Officer

Countersigned:

Wells Fargo Bank, N.A.,
  Authenticating Agent

By ________________________
   Authorized Officer

<PAGE>

                                  EXHIBIT A-19
                    [FORM OF FACE OF CLASS A-19 CERTIFICATE]

  [UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
   DEPOSITORY TRUST COMPANY TO THE DEPOSITOR OR ITS AGENT FOR REGISTRATION OF
 TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE
       NAME OF CEDE & CO. OR SUCH OTHER NAME AS REQUESTED BY AN AUTHORIZED
 REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY AND ANY PAYMENT IS MADE TO CEDE
 & CO., ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO
  ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN
                                INTEREST HEREIN.]

                        MORTGAGE PASS-THROUGH CERTIFICATE
                            SERIES 2007-4, CLASS A-19

            evidencing an interest in a pool of fixed interest rate,
            monthly pay, first lien, one- to four-family residential
                             mortgage loans sold by

                    WELLS FARGO ASSET SECURITIES CORPORATION
              (Not an interest in or obligation of the Depositor)

            THIS CERTIFICATE DOES NOT EVIDENCE AN OBLIGATION OF, OR AN INTEREST
IN, THE DEPOSITOR, THE MASTER SERVICER, THE TRUSTEE OR ANY OF THEIR AFFILIATES,
AND IS NOT INSURED OR GUARANTEED BY THE DEPOSITOR, THE MASTER SERVICER, THE
TRUSTEE OR ANY OF THEIR AFFILIATES, OR BY ANY GOVERNMENT AGENCY OR PRIVATE
INSURER.

            REDUCTION OF THE NOTIONAL AMOUNT OF THIS CERTIFICATE WILL BE MADE IN
THE MANNER DESCRIBED IN THE AGREEMENT. ACCORDINGLY, THE OUTSTANDING NOTIONAL
AMOUNT OF THIS CERTIFICATE AT ANY TIME MAY BE LESS THAN THE INITIAL NOTIONAL
AMOUNT REPRESENTED HEREBY.

Certificate No.                        Cut-Off Date: March 1, 2007

CUSIP No.: 94985R AU6                  First Distribution Date: April 25, 2007

ISIN No.: US94985RAU68                 Denomination: $             (Initial
                                       Notional Amount)

Percentage Interest evidenced          Final Scheduled Maturity Date: April 27,
by this Certificate: %                 2037

<PAGE>

            THIS CERTIFIES THAT ___________________________ is the registered
owner of the Percentage Interest evidenced by this Certificate in monthly
distributions to the Holders of the Class A-19 Certificates with respect to a
Trust Estate consisting of a pool of fixed interest rate, monthly pay, first
lien, one- to four-family residential mortgage loans (the "Mortgage Loans"),
other than the Fixed Retained Yield, if any, with respect thereto, formed by
Wells Fargo Asset Securities Corporation (hereinafter called the "Depositor,"
which term includes any successor entity under the Agreement referred to below).
The Trust Estate was created pursuant to a Pooling and Servicing Agreement dated
as of March 28, 2007 (the "Agreement") among the Depositor, Wells Fargo Bank,
N.A., as master servicer (the "Master Servicer") and HSBC Bank USA, National
Association, as trustee (the "Trustee"), a summary of certain of the pertinent
provisions of which is set forth hereinafter. To the extent not defined herein,
the capitalized terms used herein have the meanings ascribed to such terms in
the Agreement. This Certificate is issued under and is subject to the terms,
provisions and conditions of the Agreement, to which Agreement the Holder of
this Certificate by virtue of the acceptance hereof assents and by which such
Holder is bound.

            Pursuant to the terms of the Agreement, a distribution will be made
on the 25th day of each month or, if such 25th day is not a Business Day, the
Business Day immediately following (the "Distribution Date"), commencing on the
first Distribution Date specified above, to the Person in whose name this
Certificate is registered at the close of business on the Record Date, in an
amount equal to the product of the Percentage Interest evidenced by this
Certificate and the Class A Distribution Amount for the Class A-19 Certificates
required to be distributed to Holders of the Class A-19 Certificates on such
Distribution Date, subject to adjustment in certain events as specified in the
Agreement. The Class A-19 Certificates are not entitled to distributions in
respect of principal. The pass-through rate on the Class A-19 Certificates
applicable to each Distribution Date will be 6.000% per annum. The amount of
interest which accrues on this Certificate in any month will be subject to
reduction with respect to any Non-Supported Interest Shortfall, any Relief Act
Shortfall and the interest portion of certain Realized Losses allocated to the
Class A-19 Certificates, as described in the Agreement.

            Distributions on this Certificate will be made by the Paying Agent
by check mailed to the address of the Person entitled thereto, as such name and
address shall appear on the Certificate Register, unless such Person has
notified the Paying Agent pursuant to the Agreement that such payments are to be
made by wire transfer of immediately available funds. Notwithstanding the above,
the final distribution on this Certificate will be made after due notice of the
pendency of such distribution and only upon presentation and surrender of this
Certificate at the office or agency of the Paying Agent specified for that
purpose in the notice of final distribution.

            Reference is hereby made to the further provisions of this
Certificate set forth on the reverse hereof, which further provisions shall for
all purposes have the same effect as if set forth at this place.

            This Certificate constitutes a "regular interest" in a "real estate
mortgage investment conduit" as those terms are defined in Section 860G(a)(1)
and Section 860D, respectively, of the Internal Revenue Code of 1986, as
amended.

            Unless this Certificate has been countersigned by an authorized
officer of the Authenticating Agent, by manual signature, this Certificate shall
not be entitled to any benefit under the Agreement or be valid for any purpose.

<PAGE>

            IN WITNESS WHEREOF, the Paying Agent has caused this Certificate to
be duly executed as of the date set forth below.

Dated:


                                       Wells Fargo Bank, N.A.,
                                            Paying Agent


                                       By____________________________
                                            Authorized Officer

Countersigned:

Wells Fargo Bank, N.A.,
  Authenticating Agent

By ________________________
   Authorized Officer

<PAGE>

                                  EXHIBIT A-20
                    [FORM OF FACE OF CLASS A-20 CERTIFICATE]

  [UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
   DEPOSITORY TRUST COMPANY TO THE DEPOSITOR OR ITS AGENT FOR REGISTRATION OF
 TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE
       NAME OF CEDE & CO. OR SUCH OTHER NAME AS REQUESTED BY AN AUTHORIZED
 REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY AND ANY PAYMENT IS MADE TO CEDE
 & CO., ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO
  ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN
                                INTEREST HEREIN.]

                        MORTGAGE PASS-THROUGH CERTIFICATE
                            SERIES 2007-4, CLASS A-20

            evidencing an interest in a pool of fixed interest rate,
            monthly pay, first lien, one- to four-family residential
                             mortgage loans sold by

                    WELLS FARGO ASSET SECURITIES CORPORATION
              (Not an interest in or obligation of the Depositor)

            THIS CERTIFICATE DOES NOT EVIDENCE AN OBLIGATION OF, OR AN INTEREST
IN, THE DEPOSITOR, THE MASTER SERVICER, THE TRUSTEE OR ANY OF THEIR AFFILIATES,
AND IS NOT INSURED OR GUARANTEED BY THE DEPOSITOR, THE MASTER SERVICER, THE
TRUSTEE OR ANY OF THEIR AFFILIATES, OR BY ANY GOVERNMENT AGENCY OR PRIVATE
INSURER.

            DISTRIBUTIONS IN REDUCTION OF THE PRINCIPAL BALANCE OF THIS
CERTIFICATE WILL BE MADE IN THE MANNER DESCRIBED IN THE AGREEMENT. ACCORDINGLY,
THE OUTSTANDING PRINCIPAL BALANCE OF THIS CERTIFICATE AT ANY TIME MAY BE LESS
THAN THE INITIAL PRINCIPAL BALANCE REPRESENTED HEREBY.

Certificate No.                        Cut-Off Date: March 1, 2007

CUSIP No.: 94985R AV4                  First Distribution Date: April 25, 2007

ISIN No.: US94985RAV42                 Denomination: $

Percentage Interest evidenced          Final Scheduled Maturity Date: April 27,
by this Certificate: %                 2037

<PAGE>

            THIS CERTIFIES THAT ___________________________ is the registered
owner of the Percentage Interest evidenced by this Certificate in monthly
distributions to the Holders of the Class A-20 Certificates with respect to a
Trust Estate consisting of a pool of fixed interest rate, monthly pay, first
lien, one- to four-family residential mortgage loans (the "Mortgage Loans"),
other than the Fixed Retained Yield, if any, with respect thereto, formed by
Wells Fargo Asset Securities Corporation (hereinafter called the "Depositor,"
which term includes any successor entity under the Agreement referred to below).
The Trust Estate was created pursuant to a Pooling and Servicing Agreement dated
as of March 28, 2007 (the "Agreement") among the Depositor, Wells Fargo Bank,
N.A., as master servicer (the "Master Servicer") and HSBC Bank USA, National
Association, as trustee (the "Trustee"), a summary of certain of the pertinent
provisions of which is set forth hereinafter. To the extent not defined herein,
the capitalized terms used herein have the meanings ascribed to such terms in
the Agreement. This Certificate is issued under and is subject to the terms,
provisions and conditions of the Agreement, to which Agreement the Holder of
this Certificate by virtue of the acceptance hereof assents and by which such
Holder is bound.

            Pursuant to the terms of the Agreement, a distribution will be made
on the 25th day of each month or, if such 25th day is not a Business Day, the
Business Day immediately following (the "Distribution Date"), commencing on the
first Distribution Date specified above, to the Person in whose name this
Certificate is registered at the close of business on the Record Date, in an
amount equal to the product of the Percentage Interest evidenced by this
Certificate and the Class A Distribution Amount for the Class A-20 Certificates
required to be distributed to Holders of the Class A-20 Certificates on such
Distribution Date, subject to adjustment in certain events as specified in the
Agreement. Distributions in reduction of the Principal Balance of certain
Classes of Class A Certificates may not commence on the first Distribution Date
specified above. Distributions of principal will be allocated among the Classes
of Class A Certificates in accordance with the provisions of the Agreement. The
pass-through rate on the Class A-20 Certificates applicable to each Distribution
Date will be 5.500% per annum. The amount of interest which accrues on this
Certificate in any month will be subject to reduction with respect to any
Non-Supported Interest Shortfall, any Relief Act Shortfall and the interest
portion of certain Realized Losses allocated to the Class A-20 Certificates, as
described in the Agreement.

            Distributions on this Certificate will be made by the Paying Agent
by check mailed to the address of the Person entitled thereto, as such name and
address shall appear on the Certificate Register, unless such Person has
notified the Paying Agent pursuant to the Agreement that such payments are to be
made by wire transfer of immediately available funds. Notwithstanding the above,
the final distribution in reduction of the Principal Balance of this Certificate
will be made after due notice of the pendency of such distribution and only upon
presentation and surrender of this Certificate at the office or agency of the
Paying Agent specified for that purpose in the notice of final distribution.

            Reference is hereby made to the further provisions of this
Certificate set forth on the reverse hereof, which further provisions shall for
all purposes have the same effect as if set forth at this place.

            This Certificate constitutes a "regular interest" in a "real estate
mortgage investment conduit" as those terms are defined in Section 860G(a)(1)
and Section 860D, respectively, of the Internal Revenue Code of 1986, as
amended.

            Unless this Certificate has been countersigned by an authorized
officer of the Authenticating Agent, by manual signature, this Certificate shall
not be entitled to any benefit under the Agreement or be valid for any purpose.

<PAGE>

            IN WITNESS WHEREOF, the Paying Agent has caused this Certificate to
be duly executed as of the date set forth below.

Dated:


                                       Wells Fargo Bank, N.A.,
                                            Paying Agent


                                       By____________________________
                                            Authorized Officer

Countersigned:

Wells Fargo Bank, N.A.,
  Authenticating Agent

By ________________________
   Authorized Officer

<PAGE>

                                  EXHIBIT A-21
                    [FORM OF FACE OF CLASS A-21 CERTIFICATE]

  [UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
   DEPOSITORY TRUST COMPANY TO THE DEPOSITOR OR ITS AGENT FOR REGISTRATION OF
 TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE
       NAME OF CEDE & CO. OR SUCH OTHER NAME AS REQUESTED BY AN AUTHORIZED
 REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY AND ANY PAYMENT IS MADE TO CEDE
 & CO., ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO
  ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN
                                INTEREST HEREIN.]

                        MORTGAGE PASS-THROUGH CERTIFICATE
                            SERIES 2007-4, CLASS A-21

            evidencing an interest in a pool of fixed interest rate,
            monthly pay, first lien, one- to four-family residential
                             mortgage loans sold by

                    WELLS FARGO ASSET SECURITIES CORPORATION
              (Not an interest in or obligation of the Depositor)

            THIS CERTIFICATE DOES NOT EVIDENCE AN OBLIGATION OF, OR AN INTEREST
IN, THE DEPOSITOR, THE MASTER SERVICER, THE TRUSTEE OR ANY OF THEIR AFFILIATES,
AND IS NOT INSURED OR GUARANTEED BY THE DEPOSITOR, THE MASTER SERVICER, THE
TRUSTEE OR ANY OF THEIR AFFILIATES, OR BY ANY GOVERNMENT AGENCY OR PRIVATE
INSURER.

            DISTRIBUTIONS IN REDUCTION OF THE PRINCIPAL BALANCE OF THIS
CERTIFICATE WILL BE MADE IN THE MANNER DESCRIBED IN THE AGREEMENT. ACCORDINGLY,
THE OUTSTANDING PRINCIPAL BALANCE OF THIS CERTIFICATE AT ANY TIME MAY BE LESS
THAN THE INITIAL PRINCIPAL BALANCE REPRESENTED HEREBY.

Certificate No.                        Cut-Off Date: March 1, 2007

CUSIP No.: 94985R AW2                  First Distribution Date: April 25, 2007

ISIN No.: US94985RAW25                 Denomination: $

Percentage Interest evidenced          Final Scheduled Maturity Date: April 27,
by this Certificate: %                 2037

<PAGE>

            THIS CERTIFIES THAT ___________________________ is the registered
owner of the Percentage Interest evidenced by this Certificate in monthly
distributions to the Holders of the Class A-21 Certificates with respect to a
Trust Estate consisting of a pool of fixed interest rate, monthly pay, first
lien, one- to four-family residential mortgage loans (the "Mortgage Loans"),
other than the Fixed Retained Yield, if any, with respect thereto, formed by
Wells Fargo Asset Securities Corporation (hereinafter called the "Depositor,"
which term includes any successor entity under the Agreement referred to below).
The Trust Estate was created pursuant to a Pooling and Servicing Agreement dated
as of March 28, 2007 (the "Agreement") among the Depositor, Wells Fargo Bank,
N.A., as master servicer (the "Master Servicer") and HSBC Bank USA, National
Association, as trustee (the "Trustee"), a summary of certain of the pertinent
provisions of which is set forth hereinafter. To the extent not defined herein,
the capitalized terms used herein have the meanings ascribed to such terms in
the Agreement. This Certificate is issued under and is subject to the terms,
provisions and conditions of the Agreement, to which Agreement the Holder of
this Certificate by virtue of the acceptance hereof assents and by which such
Holder is bound.

            Pursuant to the terms of the Agreement, a distribution will be made
on the 25th day of each month or, if such 25th day is not a Business Day, the
Business Day immediately following (the "Distribution Date"), commencing on the
first Distribution Date specified above, to the Person in whose name this
Certificate is registered at the close of business on the Record Date, in an
amount equal to the product of the Percentage Interest evidenced by this
Certificate and the Class A Distribution Amount for the Class A-21 Certificates
required to be distributed to Holders of the Class A-21 Certificates on such
Distribution Date, subject to adjustment in certain events as specified in the
Agreement. Distributions in reduction of the Principal Balance of certain
Classes of Class A Certificates may not commence on the first Distribution Date
specified above. Distributions of principal will be allocated among the Classes
of Class A Certificates in accordance with the provisions of the Agreement. The
pass-through rate on the Class A-21 Certificates applicable to each Distribution
Date will be 5.500% per annum. The amount of interest which accrues on this
Certificate in any month will be subject to reduction with respect to any
Non-Supported Interest Shortfall, any Relief Act Shortfall and the interest
portion of certain Realized Losses allocated to the Class A-21 Certificates, as
described in the Agreement.

            Distributions on this Certificate will be made by the Paying Agent
by check mailed to the address of the Person entitled thereto, as such name and
address shall appear on the Certificate Register, unless such Person has
notified the Paying Agent pursuant to the Agreement that such payments are to be
made by wire transfer of immediately available funds. Notwithstanding the above,
the final distribution in reduction of the Principal Balance of this Certificate
will be made after due notice of the pendency of such distribution and only upon
presentation and surrender of this Certificate at the office or agency of the
Paying Agent specified for that purpose in the notice of final distribution.

            Reference is hereby made to the further provisions of this
Certificate set forth on the reverse hereof, which further provisions shall for
all purposes have the same effect as if set forth at this place.

            This Certificate constitutes a "regular interest" in a "real estate
mortgage investment conduit" as those terms are defined in Section 860G(a)(1)
and Section 860D, respectively, of the Internal Revenue Code of 1986, as
amended.

            Unless this Certificate has been countersigned by an authorized
officer of the Authenticating Agent, by manual signature, this Certificate shall
not be entitled to any benefit under the Agreement or be valid for any purpose.

<PAGE>

            IN WITNESS WHEREOF, the Paying Agent has caused this Certificate to
be duly executed as of the date set forth below.

Dated:


                                       Wells Fargo Bank, N.A.,
                                            Paying Agent


                                       By____________________________
                                            Authorized Officer

Countersigned:

Wells Fargo Bank, N.A.,
  Authenticating Agent

By ________________________
   Authorized Officer

<PAGE>

                                  EXHIBIT A-PO
                    [FORM OF FACE OF CLASS A-PO CERTIFICATE]

  [UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
   DEPOSITORY TRUST COMPANY TO THE DEPOSITOR OR ITS AGENT FOR REGISTRATION OF
 TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE
       NAME OF CEDE & CO. OR SUCH OTHER NAME AS REQUESTED BY AN AUTHORIZED
 REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY AND ANY PAYMENT IS MADE TO CEDE
 & CO., ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO
  ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN
                                INTEREST HEREIN.]

                        MORTGAGE PASS-THROUGH CERTIFICATE
                            SERIES 2007-4, CLASS A-PO

            evidencing an interest in a pool of fixed interest rate,
            monthly pay, first lien, one- to four-family residential
                             mortgage loans sold by

                    WELLS FARGO ASSET SECURITIES CORPORATION
              (Not an interest in or obligation of the Depositor)

            THIS CERTIFICATE DOES NOT EVIDENCE AN OBLIGATION OF, OR AN INTEREST
IN, THE DEPOSITOR, THE MASTER SERVICER, THE TRUSTEE OR ANY OF THEIR AFFILIATES,
AND IS NOT INSURED OR GUARANTEED BY THE DEPOSITOR, THE MASTER SERVICER, THE
TRUSTEE OR ANY OF THEIR AFFILIATES, OR BY ANY GOVERNMENT AGENCY OR PRIVATE
INSURER.

            DISTRIBUTIONS IN REDUCTION OF THE PRINCIPAL BALANCE OF THIS
CERTIFICATE WILL BE MADE IN THE MANNER DESCRIBED IN THE AGREEMENT. ACCORDINGLY,
THE OUTSTANDING PRINCIPAL BALANCE OF THIS CERTIFICATE AT ANY TIME MAY BE LESS
THAN THE INITIAL PRINCIPAL BALANCE REPRESENTED HEREBY.

Certificate No.                        Cut-Off Date: March 1, 2007

CUSIP No.: 94985R AX0                  First Distribution Date: April 25, 2007

ISIN No.: US94985RAX08                 Denomination: $

Percentage Interest evidenced          Final Scheduled Maturity Date: April 27,
by this Certificate: %                 2037

<PAGE>

            THIS CERTIFIES THAT ___________________________ is the registered
owner of the Percentage Interest evidenced by this Certificate in monthly
distributions to the Holders of the Class A-PO Certificates with respect to a
Trust Estate consisting of a pool of fixed interest rate, monthly pay, first
lien, one- to four-family residential mortgage loans (the "Mortgage Loans"),
other than the Fixed Retained Yield, if any, with respect thereto, formed by
Wells Fargo Asset Securities Corporation (hereinafter called the "Depositor,"
which term includes any successor entity under the Agreement referred to below).
The Trust Estate was created pursuant to a Pooling and Servicing Agreement dated
as of March 28, 2007 (the "Agreement") among the Depositor, Wells Fargo Bank,
N.A., as master servicer (the "Master Servicer") and HSBC Bank USA, National
Association, as trustee (the "Trustee"), a summary of certain of the pertinent
provisions of which is set forth hereinafter. To the extent not defined herein,
the capitalized terms used herein have the meanings ascribed to such terms in
the Agreement. This Certificate is issued under and is subject to the terms,
provisions and conditions of the Agreement, to which Agreement the Holder of
this Certificate by virtue of the acceptance hereof assents and by which such
Holder is bound.

            Pursuant to the terms of the Agreement, a distribution will be made
on the 25th day of each month or, if such 25th day is not a Business Day, the
Business Day immediately following (the "Distribution Date"), commencing on the
first Distribution Date specified above, to the Person in whose name this
Certificate is registered at the close of business on the Record Date, in an
amount equal to the product of the Percentage Interest evidenced by this
Certificate and the Class A Distribution Amount for the Class A-PO Certificates
required to be distributed to Holders of the Class A-PO Certificates on such
Distribution Date, subject to adjustment in certain events as specified in the
Agreement. The Class A-PO Certificates are principal only Certificates and will
not be entitled to distributions in respect of interest.

            Distributions on this Certificate will be made by the Paying Agent
by check mailed to the address of the Person entitled thereto, as such name and
address shall appear on the Certificate Register, unless such Person has
notified the Paying Agent pursuant to the Agreement that such payments are to be
made by wire transfer of immediately available funds. Notwithstanding the above,
the final distribution in reduction of the Principal Balance of this Certificate
will be made after due notice of the pendency of such distribution and only upon
presentation and surrender of this Certificate at the office or agency of the
Paying Agent specified for that purpose in the notice of final distribution.

            Reference is hereby made to the further provisions of this
Certificate set forth on the reverse hereof, which further provisions shall for
all purposes have the same effect as if set forth at this place.

            This Certificate constitutes a "regular interest" in a "real estate
mortgage investment conduit" as those terms are defined in Section 860G(a)(1)
and Section 860D, respectively, of the Internal Revenue Code of 1986, as
amended.

            Unless this Certificate has been countersigned by an authorized
officer of the Authenticating Agent, by manual signature, this Certificate shall
not be entitled to any benefit under the Agreement or be valid for any purpose.

<PAGE>

            IN WITNESS WHEREOF, the Paying Agent has caused this Certificate to
be duly executed as of the date set forth below.

Dated:


                                       Wells Fargo Bank, N.A.,
                                            Paying Agent


                                       By____________________________
                                            Authorized Officer

Countersigned:

Wells Fargo Bank, N.A.,
  Authenticating Agent

By ________________________
   Authorized Officer

<PAGE>

                                   EXHIBIT A-R
                     [FORM OF FACE OF CLASS A-R CERTIFICATE]

FOR U.S. FEDERAL INCOME TAX PURPOSES, THIS CERTIFICATE REPRESENTS THE "RESIDUAL
INTEREST" IN TWO "REAL ESTATE MORTGAGE INVESTMENT CONDUITS" AS THOSE TERMS ARE
DEFINED, RESPECTIVELY, IN SECTIONS 860G(a)(2) AND 860D OF THE INTERNAL REVENUE
CODE OF 1986, AS AMENDED (THE "CODE"). A TRANSFEREE OF THIS CERTIFICATE, BY
ACCEPTANCE HEREOF, IS DEEMED TO HAVE ACCEPTED THIS CERTIFICATE SUBJECT TO
CERTAIN RESTRICTIONS ON TRANSFERABILITY, AS SET FORTH IN SECTION 5.02(d) OF THE
AGREEMENT, AND SHALL BE REQUIRED TO FURNISH AN AFFIDAVIT TO THE TRANSFEROR AND
THE MASTER SERVICER TO THE EFFECT THAT, AMONG OTHER THINGS, IT IS NOT A
DISQUALIFIED ORGANIZATION, AS SUCH TERM IS DEFINED IN CODE SECTION 860E(e)(5),
AN AGENT (INCLUDING A BROKER, NOMINEE OR OTHER MIDDLEMAN) FOR A DISQUALIFIED
ORGANIZATION OR A NON-PERMITTED FOREIGN HOLDER, AS DEFINED IN SECTION 5.02(d) OF
THE AGREEMENT AND TO HAVE AGREED TO SUCH AMENDMENTS TO THE AGREEMENT AS MAY BE
REQUIRED TO FURTHER EFFECTUATE THE RESTRICTIONS ON TRANSFERS TO DISQUALIFIED
ORGANIZATIONS, AGENTS THEREOF OR NON-PERMITTED FOREIGN HOLDERS.

THE HOLDER OF THIS CLASS A-R CERTIFICATE, BY ACCEPTANCE HEREOF, IS DEEMED TO
HAVE AGREED TO THE DESIGNATION OF THE MASTER SERVICER AS ITS AGENT TO ACT AS
"TAX MATTERS PERSON" OF THE UPPER-TIER REMIC AND LOWER-TIER REMIC TO PERFORM THE
FUNCTIONS OF A "TAX MATTERS PARTNER" FOR PURPOSES OF SUBCHAPTER C OF CHAPTER 63
OF SUBTITLE F OF THE CODE, OR, IF SO REQUESTED BY THE MASTER SERVICER, TO ACT AS
TAX MATTERS PERSON OF THE UPPER-TIER REMIC AND LOWER-TIER REMIC.

THIS CERTIFICATE MAY NOT BE PURCHASED BY OR TRANSFERRED TO ANY PERSON WHICH IS
AN EMPLOYEE BENEFIT PLAN OR OTHER RETIREMENT ARRANGEMENT SUBJECT TO TITLE I OF
THE EMPLOYEE RETIREMENT INCOME SECURITY ACT OF 1974, AS AMENDED ("ERISA"), OR
SECTION 4975 OF THE CODE OR A GOVERNMENTAL PLAN, AS DEFINED IN SECTION 3(32) OF
ERISA SUBJECT TO ANY FEDERAL, STATE OR LOCAL LAW WHICH IS, TO A MATERIAL EXTENT,
SIMILAR TO THE FOREGOING PROVISIONS OF ERISA OR THE CODE (COLLECTIVELY, A
"PLAN"), OR ANY PERSON ACTING ON BEHALF OF OR INVESTING THE ASSETS OF A PLAN.

<PAGE>

                        MORTGAGE PASS-THROUGH CERTIFICATE
                            SERIES 2007-4, CLASS A-R

            evidencing an interest in a pool of fixed interest rate,
            monthly pay, first lien, one- to four-family residential
                             mortgage loans sold by


                    WELLS FARGO ASSET SECURITIES CORPORATION
               (Not an interest in or obligation of the Depositor)

            THIS CERTIFICATE DOES NOT EVIDENCE AN OBLIGATION OF, OR AN INTEREST
IN, THE DEPOSITOR, THE MASTER SERVICER, THE TRUSTEE OR ANY OF THEIR AFFILIATES,
AND IS NOT INSURED OR GUARANTEED BY THE DEPOSITOR, THE MASTER SERVICER, THE
TRUSTEE OR ANY OF THEIR AFFILIATES, OR BY ANY GOVERNMENT AGENCY OR PRIVATE
INSURER.

            DISTRIBUTIONS IN REDUCTION OF THE PRINCIPAL BALANCE OF THIS
CERTIFICATE WILL BE MADE IN THE MANNER DESCRIBED IN THE AGREEMENT. ACCORDINGLY,
THE OUTSTANDING PRINCIPAL BALANCE OF THIS CERTIFICATE AT ANY TIME MAY BE LESS
THAN THE INITIAL PRINCIPAL BALANCE REPRESENTED HEREBY.

Certificate No.                  Cut-Off Date: March 1, 2007

CUSIP No.: 94985R AY8            First Distribution Date: April 25, 2007

ISIN No.: US94985RAY80           Denomination: $

Percentage Interest evidenced
by this Certificate: %           Final Scheduled Maturity Date: April 27, 2037

<PAGE>

            THIS CERTIFIES THAT __________________________ is the registered
owner of the Percentage Interest evidenced by this Certificate in monthly
distributions to the Holder of the Class A-R Certificate with respect to a Trust
Estate consisting of a pool of fixed interest rate, monthly pay, first lien,
one- to four-family residential mortgage loans (the "Mortgage Loans"), other
than the Fixed Retained Yield, if any, with respect thereto, formed by Wells
Fargo Asset Securities Corporation (hereinafter called the "Depositor," which
term includes any successor entity under the Agreement referred to below). The
Trust Estate was created pursuant to a Pooling and Servicing Agreement dated as
of March 28, 2007 (the "Agreement") among the Depositor, Wells Fargo Bank, N.A.,
as master servicer (the "Master Servicer") and HSBC Bank USA, National
Association, as trustee (the "Trustee"), a summary of certain of the pertinent
provisions of which is set forth hereinafter. To the extent not defined herein,
the capitalized terms used herein have the meanings ascribed to such terms in
the Agreement. This Certificate is issued under and is subject to the terms,
provisions and conditions of the Agreement, to which Agreement the Holder of
this Certificate by virtue of the acceptance hereof assents and by which such
Holder is bound.

            Pursuant to the terms of the Agreement, a distribution will be made
on the 25th day of each month or, if such 25th day is not a Business Day, the
Business Day immediately following (the "Distribution Date"), commencing on the
first Distribution Date specified above, to the Person in whose name this
Certificate is registered at the close of business on the Record Date, in an
amount equal to the product of the Percentage Interest evidenced by this
Certificate and the Class A Distribution Amount for the Class A-R Certificate
required to be distributed to the Holder of the Class A-R Certificate on such
Distribution Date, subject to adjustment in certain events as specified in the
Agreement. Distributions in reduction of the Principal Balance of certain
Classes of Class A Certificates may not commence on the first Distribution Date
specified above. Distributions of principal will be allocated among the Classes
of Class A Certificates in accordance with the provisions of the Agreement. The
pass-through rate on the Class A-R Certificate applicable to each Distribution
Date will be 6.000% per annum. The amount of interest which accrues on this
Certificate in any month will be subject to reduction with respect to any
Non-Supported Interest Shortfall, any Relief Act Shortfall and the interest
portion of certain Realized Losses allocated to the Class A-R Certificate, as
described in the Agreement.

            Distributions on this Certificate will be made by the Paying Agent
by check mailed to the address of the Person entitled thereto, as such name and
address shall appear on the Certificate Register, unless such Person has
notified the Paying Agent pursuant to the Agreement that such payments are to be
made by wire transfer of immediately available funds. Notwithstanding the above,
the final distribution on this Certificate will be made after due notice of the
pendency of such distribution and only upon presentation and surrender of this
Certificate at the office or agency of the Paying Agent specified for that
purpose in the notice of final distribution.

            Reference is hereby made to the further provisions of this
Certificate set forth on the reverse hereof, which further provisions shall for
all purposes have the same effect as if set forth at this place.

            Unless this Certificate has been countersigned by an authorized
officer of the Authenticating Agent, by manual signature, this Certificate shall
not be entitled to any benefit under the Agreement or be valid for any purpose.

<PAGE>

            IN WITNESS WHEREOF, the Paying Agent has caused this Certificate to
be duly executed as of the date set forth below.

Dated:


                                       Wells Fargo Bank, N.A.,
                                            Paying Agent


                                       By____________________________
                                            Authorized Officer

Countersigned:

Wells Fargo Bank, N.A.,
  Authenticating Agent


By ________________________
      Authorized Officer

<PAGE>

                                   EXHIBIT B-1
                     [FORM OF FACE OF CLASS B-1 CERTIFICATE]

THIS CERTIFICATE IS SUBORDINATED IN RIGHT OF PAYMENT TO THE CLASS A CERTIFICATES
AS DESCRIBED IN THE AGREEMENT REFERRED TO HEREIN.

[UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
DEPOSITORY TRUST COMPANY TO THE DEPOSITOR OR ITS AGENT FOR REGISTRATION OF
TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE
NAME OF CEDE & CO. OR SUCH OTHER NAME AS REQUESTED BY AN AUTHORIZED
REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY AND ANY PAYMENT IS MADE TO CEDE &
CO., ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO
ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN
INTEREST HEREIN.]

                        MORTGAGE PASS-THROUGH CERTIFICATE
                            SERIES 2007-4, CLASS B-1

   evidencing an interest in a pool of fixed interest rate, monthly pay, first
          lien, one- to four-family residential mortgage loans sold by

                    WELLS FARGO ASSET SECURITIES CORPORATION
               (Not an interest in or obligation of the Depositor)

            THIS CERTIFICATE DOES NOT EVIDENCE AN OBLIGATION OF, OR AN INTEREST
IN, THE DEPOSITOR, THE MASTER SERVICER, THE TRUSTEE OR ANY OF THEIR AFFILIATES,
AND IS NOT INSURED OR GUARANTEED BY THE DEPOSITOR, THE MASTER SERVICER, THE
TRUSTEE OR ANY OF THEIR AFFILIATES, OR BY ANY GOVERNMENT AGENCY OR PRIVATE
INSURER.

            DISTRIBUTIONS IN REDUCTION OF THE PRINCIPAL BALANCE OF THIS
CERTIFICATE WILL BE MADE IN THE MANNER DESCRIBED IN THE AGREEMENT. ACCORDINGLY,
THE OUTSTANDING PRINCIPAL BALANCE OF THIS CERTIFICATE AT ANY TIME MAY BE LESS
THAN THE INITIAL PRINCIPAL BALANCE REPRESENTED HEREBY.

Certificate No.                        Cut-Off Date: March 1, 2007

CUSIP No.: 94985R AZ5                  First Distribution Date: April 25, 2007

ISIN No.: US94985RAZ55                 Denomination: $

Percentage Interest evidenced          Final Scheduled Maturity Date: April 27,
by this Certificate: %                 2037

<PAGE>

            THIS CERTIFIES THAT ____________________________ is the registered
owner of the Percentage Interest evidenced by this Certificate in monthly
distributions to the Holders of the Class B-1 Certificates with respect to a
Trust Estate consisting of a pool of fixed interest rate, monthly pay, first
lien, one- to four-family residential mortgage loans (the "Mortgage Loans"),
other than the Fixed Retained Yield, if any, with respect thereto, formed by
Wells Fargo Asset Securities Corporation (hereinafter called the "Depositor,"
which term includes any successor entity under the Agreement referred to below).
The Trust Estate was created pursuant to a Pooling and Servicing Agreement dated
as of March 28, 2007 (the "Agreement") among the Depositor, Wells Fargo Bank,
N.A., as master servicer (the "Master Servicer") and HSBC Bank USA, National
Association, as trustee (the "Trustee"), a summary of certain of the pertinent
provisions of which is set forth hereinafter. To the extent not defined herein,
the capitalized terms used herein have the meanings ascribed to such terms in
the Agreement. This Certificate is issued under and is subject to the terms,
provisions and conditions of the Agreement, to which Agreement the Holder of
this Certificate by virtue of the acceptance hereof assents and by which such
Holder is bound.

            Pursuant to the terms of the Agreement, a distribution will be made
on the 25th day of each month or, if such 25th day is not a Business Day, the
Business Day immediately following (the "Distribution Date"), commencing on the
first Distribution Date specified above, to the Person in whose name this
Certificate is registered at the close of business on the Record Date, in an
amount equal to the product of the Percentage Interest evidenced by this
Certificate and, subject to the prior rights of the Class A Certificates as
specified in the Agreement, any Class B-1 Distribution Amount required to be
distributed to Holders of the Class B-1 Certificates on such Distribution Date,
subject to adjustment, in certain events, as specified in the Agreement. The
pass-through rate on the Class B-1 Certificates applicable to each Distribution
Date will be 6.000% per annum. The amount of interest which accrues on this
Certificate in any month will be subject to reduction with respect to any
Non-Supported Interest Shortfall and any Relief Act Shortfall allocated to the
Class B-1 Certificates, as described in the Agreement.

            Distributions on this Certificate will be made by the Paying Agent
by check mailed to the address of the Person entitled thereto, as such name and
address shall appear on the Certificate Register, unless such Person has
notified the Paying Agent pursuant to the Agreement that such payments are to be
made by wire transfer of immediately available funds. Notwithstanding the above,
the final distribution in reduction of the Principal Balance of this Certificate
will be made after due notice of the pendency of such distribution and only upon
presentation and surrender of this Certificate at the office or agency of the
Paying Agent specified for that purpose in the notice of final distribution.

            Reference is hereby made to the further provisions of this
Certificate set forth on the reverse hereof, which further provisions shall for
all purposes have the same effect as if set forth at this place.

            This Certificate constitutes a "regular interest" in a "real estate
mortgage investment conduit" as those terms are defined in Section 860G(a)(1)
and Section 860D, respectively, of the Internal Revenue Code of 1986, as
amended.

            Unless this Certificate has been countersigned by an authorized
officer of the Authenticating Agent, by manual signature, this Certificate shall
not be entitled to any benefit under the Agreement or be valid for any purpose.

<PAGE>

            IN WITNESS WHEREOF, the Paying Agent has caused this Certificate to
be duly executed as of the date set forth below.

Dated:


                                       Wells Fargo Bank, N.A.,
                                            Paying Agent


                                       By____________________________
                                            Authorized Officer

Countersigned:

Wells Fargo Bank, N.A.,
  Authenticating Agent

By ________________________
   Authorized Officer

<PAGE>

                                   EXHIBIT B-2
                     [FORM OF FACE OF CLASS B-2 CERTIFICATE]

THIS CERTIFICATE IS SUBORDINATED IN RIGHT OF PAYMENT TO THE CLASS A CERTIFICATES
AND THE CLASS B-1 CERTIFICATES AS DESCRIBED IN THE AGREEMENT REFERRED TO HEREIN.

[UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
DEPOSITORY TRUST COMPANY TO THE DEPOSITOR OR ITS AGENT FOR REGISTRATION OF
TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE
NAME OF CEDE & CO. OR SUCH OTHER NAME AS REQUESTED BY AN AUTHORIZED
REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY AND ANY PAYMENT IS MADE TO CEDE &
CO., ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO
ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN
INTEREST HEREIN.]

                        MORTGAGE PASS-THROUGH CERTIFICATE
                            SERIES 2007-4, CLASS B-2

   evidencing an interest in a pool of fixed interest rate, monthly pay, first
          lien, one- to four-family residential mortgage loans sold by

                    WELLS FARGO ASSET SECURITIES CORPORATION
               (Not an interest in or obligation of the Depositor)

            THIS CERTIFICATE DOES NOT EVIDENCE AN OBLIGATION OF, OR AN INTEREST
IN, THE DEPOSITOR, THE MASTER SERVICER, THE TRUSTEE OR ANY OF THEIR AFFILIATES,
AND IS NOT INSURED OR GUARANTEED BY THE DEPOSITOR, THE MASTER SERVICER, THE
TRUSTEE OR ANY OF THEIR AFFILIATES, OR BY ANY GOVERNMENT AGENCY OR PRIVATE
INSURER.

            DISTRIBUTIONS IN REDUCTION OF THE PRINCIPAL BALANCE OF THIS
CERTIFICATE WILL BE MADE IN THE MANNER DESCRIBED IN THE AGREEMENT. ACCORDINGLY,
THE OUTSTANDING PRINCIPAL BALANCE OF THIS CERTIFICATE AT ANY TIME MAY BE LESS
THAN THE INITIAL PRINCIPAL BALANCE REPRESENTED HEREBY.

Certificate No.                        Cut-Off Date: March 1, 2007

CUSIP No.: 94985R BA9                  First Distribution Date: April 25, 2007

ISIN No.: US94985RBA95                 Denomination: $

Percentage Interest evidenced          Final Scheduled Maturity Date: April 27,
by this Certificate: %                 2037

<PAGE>

            THIS CERTIFIES THAT ____________________________ is the registered
owner of the Percentage Interest evidenced by this Certificate in monthly
distributions to the Holders of the Class B-2 Certificates with respect to a
Trust Estate consisting of a pool of fixed interest rate, monthly pay, first
lien, one- to four-family residential mortgage loans (the "Mortgage Loans"),
other than the Fixed Retained Yield, if any, with respect thereto, formed by
Wells Fargo Asset Securities Corporation (hereinafter called the "Depositor,"
which term includes any successor entity under the Agreement referred to below).
The Trust Estate was created pursuant to a Pooling and Servicing Agreement dated
as of March 28, 2007 (the "Agreement") among the Depositor, Wells Fargo Bank,
N.A., as master servicer (the "Master Servicer") and HSBC Bank USA, National
Association, as trustee (the "Trustee"), a summary of certain of the pertinent
provisions of which is set forth hereinafter. To the extent not defined herein,
the capitalized terms used herein have the meanings ascribed to such terms in
the Agreement. This Certificate is issued under and is subject to the terms,
provisions and conditions of the Agreement, to which Agreement the Holder of
this Certificate by virtue of the acceptance hereof assents and by which such
Holder is bound.

            Pursuant to the terms of the Agreement, a distribution will be made
on the 25th day of each month or, if such 25th day is not a Business Day, the
Business Day immediately following (the "Distribution Date"), commencing on the
first Distribution Date specified above, to the Person in whose name this
Certificate is registered at the close of business on the Record Date, in an
amount equal to the product of the Percentage Interest evidenced by this
Certificate and, subject to the prior rights of the Class A Certificates and
each Class of Class B Certificates bearing a lower numerical designation as
specified in the Agreement, any Class B-2 Distribution Amount required to be
distributed to Holders of the Class B-2 Certificates on such Distribution Date,
subject to adjustment, in certain events, as specified in the Agreement. The
pass-through rate on the Class B-2 Certificates applicable to each Distribution
Date will be 6.000% per annum. The amount of interest which accrues on this
Certificate in any month will be subject to reduction with respect to any
Non-Supported Interest Shortfall and any Relief Act Shortfall allocated to the
Class B-2 Certificates, as described in the Agreement.

            Distributions on this Certificate will be made by the Paying Agent
by check mailed to the address of the Person entitled thereto, as such name and
address shall appear on the Certificate Register, unless such Person has
notified the Paying Agent pursuant to the Agreement that such payments are to be
made by wire transfer of immediately available funds. Notwithstanding the above,
the final distribution in reduction of the Principal Balance of this Certificate
will be made after due notice of the pendency of such distribution and only upon
presentation and surrender of this Certificate at the office or agency of the
Paying Agent specified for that purpose in the notice of final distribution.

            Reference is hereby made to the further provisions of this
Certificate set forth on the reverse hereof, which further provisions shall for
all purposes have the same effect as if set forth at this place.

            This Certificate constitutes a "regular interest" in a "real estate
mortgage investment conduit" as those terms are defined in Section 860G(a)(1)
and Section 860D, respectively, of the Internal Revenue Code of 1986, as
amended.

            Unless this Certificate has been countersigned by an authorized
officer of the Authenticating Agent, by manual signature, this Certificate shall
not be entitled to any benefit under the Agreement or be valid for any purpose.

<PAGE>

            IN WITNESS WHEREOF, the Paying Agent has caused this Certificate to
be duly executed as of the date set forth below.

Dated:


                                       Wells Fargo Bank, N.A.,
                                            Paying Agent


                                       By____________________________
                                            Authorized Officer

Countersigned:

Wells Fargo Bank, N.A.,
  Authenticating Agent

By ________________________
   Authorized Officer

<PAGE>

                                   EXHIBIT B-3

                     [FORM OF FACE OF CLASS B-3 CERTIFICATE]

THIS CERTIFICATE IS SUBORDINATED IN RIGHT OF PAYMENT TO THE CLASS A
CERTIFICATES, THE CLASS B-1 CERTIFICATES AND THE CLASS B-2 CERTIFICATES AS
DESCRIBED IN THE AGREEMENT REFERRED TO HEREIN.

[UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
DEPOSITORY TRUST COMPANY TO THE DEPOSITOR OR ITS AGENT FOR REGISTRATION OF
TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE
NAME OF CEDE & CO. OR SUCH OTHER NAME AS REQUESTED BY AN AUTHORIZED
REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY AND ANY PAYMENT IS MADE TO CEDE &
CO., ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO
ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN
INTEREST HEREIN.]

                        MORTGAGE PASS-THROUGH CERTIFICATE
                            SERIES 2007-4, CLASS B-3

   evidencing an interest in a pool of fixed interest rate, monthly pay, first
          lien, one- to four-family residential mortgage loans sold by

                    WELLS FARGO ASSET SECURITIES CORPORATION
               (Not an interest in or obligation of the Depositor)

            THIS CERTIFICATE DOES NOT EVIDENCE AN OBLIGATION OF, OR AN INTEREST
IN, THE DEPOSITOR, THE MASTER SERVICER, THE TRUSTEE OR ANY OF THEIR AFFILIATES,
AND IS NOT INSURED OR GUARANTEED BY THE DEPOSITOR, THE MASTER SERVICER, THE
TRUSTEE OR ANY OF THEIR AFFILIATES, OR BY ANY GOVERNMENT AGENCY OR PRIVATE
INSURER.

            DISTRIBUTIONS IN REDUCTION OF THE PRINCIPAL BALANCE OF THIS
CERTIFICATE WILL BE MADE IN THE MANNER DESCRIBED IN THE AGREEMENT. ACCORDINGLY,
THE OUTSTANDING PRINCIPAL BALANCE OF THIS CERTIFICATE AT ANY TIME MAY BE LESS
THAN THE INITIAL PRINCIPAL BALANCE REPRESENTED HEREBY.

Certificate No.                        Cut-Off Date: March 1, 2007

CUSIP No.: 94985R BB7                  First Distribution Date: April 25, 2007

ISIN No.: US94985RBB78                 Denomination: $

Percentage Interest evidenced          Final Scheduled Maturity Date: April 27,
by this Certificate: %                 2037

<PAGE>

            THIS CERTIFIES THAT _______________________________ is the
registered owner of the Percentage Interest evidenced by this Certificate in
monthly distributions to the Holders of the Class B-3 Certificates with respect
to a Trust Estate consisting of a pool of fixed interest rate, monthly pay,
first lien, one- to four-family residential mortgage loans (the "Mortgage
Loans"), other than the Fixed Retained Yield, if any, with respect thereto,
formed by Wells Fargo Asset Securities Corporation (hereinafter called the
"Depositor," which term includes any successor entity under the Agreement
referred to below). The Trust Estate was created pursuant to a Pooling and
Servicing Agreement dated as of March 28, 2007 (the "Agreement") among the
Depositor, Wells Fargo Bank, N.A., as master servicer (the "Master Servicer")
and HSBC Bank USA, National Association, as trustee (the "Trustee"), a summary
of certain of the pertinent provisions of which is set forth hereinafter. To the
extent not defined herein, the capitalized terms used herein have the meanings
ascribed to such terms in the Agreement. This Certificate is issued under and is
subject to the terms, provisions and conditions of the Agreement, to which
Agreement the Holder of this Certificate by virtue of the acceptance hereof
assents and by which such Holder is bound.

            Pursuant to the terms of the Agreement, a distribution will be made
on the 25th day of each month or, if such 25th day is not a Business Day, the
Business Day immediately following (the "Distribution Date"), commencing on the
first Distribution Date specified above, to the Person in whose name this
Certificate is registered at the close of business on the Record Date, in an
amount equal to the product of the Percentage Interest evidenced by this
Certificate and, subject to the prior rights of the Class A Certificates and
each Class of Class B Certificates bearing a lower numerical designation as
specified in the Agreement, any Class B-3 Distribution Amount required to be
distributed to Holders of the Class B-3 Certificates on such Distribution Date,
subject to adjustment, in certain events, as specified in the Agreement. The
pass-through rate on the Class B-3 Certificates applicable to each Distribution
Date will be 6.000% per annum. The amount of interest which accrues on this
Certificate in any month will be subject to reduction with respect to any
Non-Supported Interest Shortfall and any Relief Act Shortfall allocated to the
Class B-3 Certificates, as described in the Agreement.

            Distributions on this Certificate will be made by the Paying Agent
by check mailed to the address of the Person entitled thereto, as such name and
address shall appear on the Certificate Register, unless such Person has
notified the Paying Agent pursuant to the Agreement that such payments are to be
made by wire transfer of immediately available funds. Notwithstanding the above,
the final distribution in reduction of the Principal Balance of this Certificate
will be made after due notice of the pendency of such distribution and only upon
presentation and surrender of this Certificate at the office or agency of the
Paying Agent specified for that purpose in the notice of final distribution.

            Reference is hereby made to the further provisions of this
Certificate set forth on the reverse hereof, which further provisions shall for
all purposes have the same effect as if set forth at this place.

            This Certificate constitutes a "regular interest" in a "real estate
mortgage investment conduit" as those terms are defined in Section 860G(a)(1)
and Section 860D, respectively, of the Internal Revenue Code of 1986, as
amended.

            Unless this Certificate has been countersigned by an authorized
officer of the Authenticating Agent, by manual signature, this Certificate shall
not be entitled to any benefit under the Agreement or be valid for any purpose.

<PAGE>

            IN WITNESS WHEREOF, the Paying Agent has caused this Certificate to
be duly executed as of the date set forth below.

Dated:


                                       Wells Fargo Bank, N.A.,
                                            Paying Agent


                                       By____________________________
                                            Authorized Officer

Countersigned:

Wells Fargo Bank, N.A.,
  Authenticating Agent

By ________________________
   Authorized Officer


<PAGE>

                                   EXHIBIT B-4
                     [FORM OF FACE OF CLASS B-4 CERTIFICATE]

[UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
DEPOSITORY TRUST COMPANY TO THE DEPOSITOR OR ITS AGENT FOR REGISTRATION OF
TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE
NAME OF CEDE & CO. OR SUCH OTHER NAME AS REQUESTED BY AN AUTHORIZED
REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY AND ANY PAYMENT IS MADE TO CEDE &
CO., ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO
ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN
INTEREST HEREIN.]

THIS CERTIFICATE IS SUBORDINATED IN RIGHT OF PAYMENT TO THE CLASS A
CERTIFICATES, THE CLASS B-1 CERTIFICATES, THE CLASS B-2 CERTIFICATES AND THE
CLASS B-3 CERTIFICATES AS DESCRIBED IN THE AGREEMENT REFERRED TO HEREIN.

THIS CERTIFICATE HAS NOT BEEN AND WILL NOT BE REGISTERED UNDER THE SECURITIES
ACT OF 1933, AS AMENDED, OR THE SECURITIES LAWS OF ANY STATE AND MAY NOT BE
RESOLD OR TRANSFERRED UNLESS IT IS REGISTERED PURSUANT TO SUCH ACT AND LAWS OR
IS SOLD OR TRANSFERRED IN TRANSACTIONS WHICH ARE EXEMPT FROM REGISTRATION UNDER
SUCH ACT AND UNDER APPLICABLE STATE LAW AND IS TRANSFERRED IN ACCORDANCE WITH
THE PROVISIONS OF SECTION 5.02 OF THE AGREEMENT REFERRED TO HEREIN.

THE INITIAL PURCHASER IN THIS CERTIFICATE, AND EACH SUBSEQUENT PURCHASER OF THIS
CERTIFICATE, BY PURCHASING THIS CERTIFICATE OR AN INTEREST HEREIN, IS DEEMED TO
HAVE AGREED TO COMPLY WITH CERTAIN TRANSFER REQUIREMENTS SET FORTH IN THE
POOLING AND SERVICING AGREEMENT REFERRED TO HEREIN.

EXCEPT AS PROVIDED IN SECTION 5.02(C) OF THE AGREEMENT REFERRED TO HEREIN, THIS
CERTIFICATE MAY NOT BE PURCHASED BY OR TRANSFERRED TO ANY PERSON THAT HAS NOT
DELIVERED A REPRESENTATION LETTER STATING EITHER (A) THAT THE TRANSFEREE IS NOT
AN EMPLOYEE BENEFIT PLAN OR OTHER RETIREMENT ARRANGEMENT SUBJECT TO TITLE I OF
THE EMPLOYEE RETIREMENT INCOME SECURITY ACT OF 1974, AS AMENDED ("ERISA"), OR
SECTION 4975 OF THE INTERNAL REVENUE CODE OF 1986, AS AMENDED (THE "CODE"), OR A
GOVERNMENTAL PLAN, AS DEFINED IN SECTION 3(32) OF ERISA, SUBJECT TO ANY FEDERAL,
STATE OR LOCAL LAW WHICH IS, TO A MATERIAL EXTENT, SIMILAR TO THE FOREGOING
PROVISIONS OF ERISA OR THE CODE (COLLECTIVELY, A "PLAN"), AND IS NOT ACTING ON
BEHALF OF OR INVESTING THE ASSETS OF A PLAN OR (B) SUBJECT TO CERTAIN CONDITIONS
SET FORTH IN THE AGREEMENT, THAT THE SOURCE OF FUNDS USED TO PURCHASE THIS
CERTIFICATE IS AN "INSURANCE COMPANY GENERAL ACCOUNT." EACH PERSON WHO ACQUIRES
THIS CERTIFICATE OR ANY INTEREST THEREIN SHALL BE DEEMED TO HAVE MADE THE
REPRESENTATIONS REQUIRED BY THE REPRESENTATION LETTER REFERRED TO IN THE
PRECEDING SENTENCE, UNLESS SUCH PERSON SHALL HAVE PROVIDED SUCH REPRESENTATION
LETTER OR THE OPINION OF COUNSEL REFERRED TO IN SECTION 5.02(C) OF THE AGREEMENT
REFERRED TO HEREIN TO THE MASTER SERVICER AND DEPOSITOR.

<PAGE>

                        MORTGAGE PASS-THROUGH CERTIFICATE
                            SERIES 2007-4, CLASS B-4

   evidencing an interest in a pool of fixed interest rate, monthly pay, first
          lien, one- to four-family residential mortgage loans sold by

                    WELLS FARGO ASSET SECURITIES CORPORATION
               (Not an interest in or obligation of the Depositor)

            THIS CERTIFICATE DOES NOT EVIDENCE AN OBLIGATION OF, OR AN INTEREST
IN, THE DEPOSITOR, THE MASTER SERVICER, THE TRUSTEE OR ANY OF THEIR AFFILIATES,
AND IS NOT INSURED OR GUARANTEED BY THE DEPOSITOR, THE MASTER SERVICER, THE
TRUSTEE OR ANY OF THEIR AFFILIATES, OR BY ANY GOVERNMENT AGENCY OR PRIVATE
INSURER.

            DISTRIBUTIONS IN REDUCTION OF THE PRINCIPAL BALANCE OF THIS
CERTIFICATE WILL BE MADE IN THE MANNER DESCRIBED IN THE AGREEMENT. ACCORDINGLY,
THE OUTSTANDING PRINCIPAL BALANCE OF THIS CERTIFICATE AT ANY TIME MAY BE LESS
THAN THE INITIAL PRINCIPAL BALANCE REPRESENTED HEREBY.

Certificate No.                        Cut-Off Date: March 1, 2007

CUSIP No.: 94985R BC5                  First Distribution Date: April 25, 2007

ISIN No.: US94985RBC51                 Denomination: $

Percentage Interest evidenced          Final Scheduled Maturity Date: April 27,
by this Certificate: %                 2037

<PAGE>

            THIS CERTIFIES THAT ____________________________ is the registered
owner of the Percentage Interest evidenced by this Certificate in monthly
distributions to the Holders of the Class B-4 Certificates with respect to a
Trust Estate consisting of a pool of fixed interest rate, monthly pay, first
lien, one- to four-family residential mortgage loans (the "Mortgage Loans"),
other than the Fixed Retained Yield, if any, with respect thereto, formed by
Wells Fargo Asset Securities Corporation (hereinafter called the "Depositor,"
which term includes any successor entity under the Agreement referred to below).
The Trust Estate was created pursuant to a Pooling and Servicing Agreement dated
as of March 28, 2007 (the "Agreement") among the Depositor, Wells Fargo Bank,
N.A., as master servicer (the "Master Servicer") and HSBC Bank USA, National
Association, as trustee (the "Trustee"), a summary of certain of the pertinent
provisions of which is set forth hereinafter. To the extent not defined herein,
the capitalized terms used herein have the meanings ascribed to such terms in
the Agreement. This Certificate is issued under and is subject to the terms,
provisions and conditions of the Agreement, to which Agreement the Holder of
this Certificate by virtue of the acceptance hereof assents and by which such
Holder is bound.

            Pursuant to the terms of the Agreement, a distribution will be made
on the 25th day of each month or, if such 25th day is not a Business Day, the
Business Day immediately following (the "Distribution Date"), commencing on the
first Distribution Date specified above, to the Person in whose name this
Certificate is registered at the close of business on the Record Date, in an
amount equal to the product of the Percentage Interest evidenced by this
Certificate and, subject to the prior rights of the Class A Certificates and
each Class of Class B Certificates bearing a lower numerical designation as
specified in the Agreement, any Class B-4 Distribution Amount required to be
distributed to Holders of the Class B-4 Certificates on such Distribution Date,
subject to adjustment, in certain events, as specified in the Agreement. The
pass-through rate on the Class B-4 Certificates applicable to each Distribution
Date will be 6.000% per annum. The amount of interest which accrues on this
Certificate in any month will be subject to reduction with respect to any
Non-Supported Interest Shortfall and any Relief Act Shortfall allocated to the
Class B-4 Certificates, as described in the Agreement.

            Distributions on this Certificate will be made by the Paying Agent
by check mailed to the address of the Person entitled thereto, as such name and
address shall appear on the Certificate Register, unless such Person has
notified the Paying Agent pursuant to the Agreement that such payments are to be
made by wire transfer of immediately available funds. Notwithstanding the above,
the final distribution in reduction of the Principal Balance of this Certificate
will be made after due notice of the pendency of such distribution and only upon
presentation and surrender of this Certificate at the office or agency of the
Paying Agent specified for that purpose in the notice of final distribution.

            No transfer of a Class B-4 Certificate will be made unless such
transfer is exempt from the registration requirements of the Securities Act of
1933, as amended, and any applicable state securities laws or is made in
accordance with said Act and laws. In the event that such a transfer is desired
to be made by the Holder hereof, the transferee will be required to execute an
investment letter in the form described in the Agreement. The Holder hereof
desiring to effect such transfer shall, and does hereby agree to, indemnify the
Trustee, the Depositor, the Master Servicer, and any Paying Agent against any
liability that may result if the transfer is not so exempt or is not made in
accordance with such Federal and state laws. The representations required in any
investment letter shall be deemed to have been made in connection with a
transfer of a Class B-4 Certificate that is a Book-Entry Certificate. In
connection with any such transfer, the Master Servicer will also require (i) a
representation letter, in the form as described in the Agreement, stating either
(a) that the transferee is not a Plan and is not acting on behalf of a Plan or
using the assets of a Plan to effect such purchase or (b) subject to certain
conditions described in the Agreement, that the source of funds used to purchase
this Certificate is an "insurance company general account," or (ii) if such
transferee is a Plan, (a) an opinion of counsel acceptable to and in form and
substance satisfactory to the Master Servicer and the Depositor with respect to
certain matters and (b) such other documentation as the Depositor or the Master
Servicer may require, as described in the Agreement. For purposes of clause (i)
of this paragraph, each person who acquires this certificate or any interest
therein shall be deemed to have made the representations required by the
representation letter referred to in the preceding sentence, unless such person
shall have provided such representation letter or the opinion of counsel
referred to in the preceding sentence to the Depositor and Master Servicer.

            Reference is hereby made to the further provisions of this
Certificate set forth on the reverse hereof, which further provisions shall for
all purposes have the same effect as if set forth at this place.

            This Certificate constitutes a "regular interest" in a "real estate
mortgage investment conduit" as those terms are defined in Section 860G(a)(1)
and Section 860D, respectively, of the Internal Revenue Code of 1986, as
amended.

            Unless this Certificate has been countersigned by an authorized
officer of the Authenticating Agent, by manual signature, this Certificate shall
not be entitled to any benefit under the Agreement or be valid for any purpose.

<PAGE>

            IN WITNESS WHEREOF, the Paying Agent has caused this Certificate to
be duly executed as of the date set forth below.

Dated:


                                       Wells Fargo Bank, N.A.,
                                            Paying Agent


                                       By____________________________
                                            Authorized Officer

Countersigned:

Wells Fargo Bank, N.A.,
  Authenticating Agent

By ________________________
   Authorized Officer

<PAGE>

                                   EXHIBIT B-5
                     [FORM OF FACE OF CLASS B-5 CERTIFICATE]

[UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
DEPOSITORY TRUST COMPANY TO THE DEPOSITOR OR ITS AGENT FOR REGISTRATION OF
TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE
NAME OF CEDE & CO. OR SUCH OTHER NAME AS REQUESTED BY AN AUTHORIZED
REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY AND ANY PAYMENT IS MADE TO CEDE &
CO., ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO
ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN
INTEREST HEREIN.]

THIS CERTIFICATE IS SUBORDINATED IN RIGHT OF PAYMENT TO THE CLASS A
CERTIFICATES, THE CLASS B-1 CERTIFICATES, THE CLASS B-2 CERTIFICATES, THE CLASS
B-3 CERTIFICATES AND THE CLASS B-4 CERTIFICATES AS DESCRIBED IN THE AGREEMENT
REFERRED TO HEREIN.

THIS CERTIFICATE HAS NOT BEEN AND WILL NOT BE REGISTERED UNDER THE SECURITIES
ACT OF 1933, AS AMENDED, OR THE SECURITIES LAWS OF ANY STATE AND MAY NOT BE
RESOLD OR TRANSFERRED UNLESS IT IS REGISTERED PURSUANT TO SUCH ACT AND LAWS OR
IS SOLD OR TRANSFERRED IN TRANSACTIONS WHICH ARE EXEMPT FROM REGISTRATION UNDER
SUCH ACT AND UNDER APPLICABLE STATE LAW AND IS TRANSFERRED IN ACCORDANCE WITH
THE PROVISIONS OF SECTION 5.02 OF THE AGREEMENT REFERRED TO HEREIN.

THE INITIAL PURCHASER IN THIS CERTIFICATE, AND EACH SUBSEQUENT PURCHASER OF THIS
CERTIFICATE, BY PURCHASING THIS CERTIFICATE OR AN INTEREST HEREIN, IS DEEMED TO
HAVE AGREED TO COMPLY WITH CERTAIN TRANSFER REQUIREMENTS SET FORTH IN THE
POOLING AND SERVICING AGREEMENT REFERRED TO HEREIN.

EXCEPT AS PROVIDED IN SECTION 5.02(C) OF THE AGREEMENT REFERRED TO HEREIN, THIS
CERTIFICATE MAY NOT BE PURCHASED BY OR TRANSFERRED TO ANY PERSON THAT HAS NOT
DELIVERED A REPRESENTATION LETTER STATING EITHER (A) THAT THE TRANSFEREE IS NOT
AN EMPLOYEE BENEFIT PLAN OR OTHER RETIREMENT ARRANGEMENT SUBJECT TO TITLE I OF
THE EMPLOYEE RETIREMENT INCOME SECURITY ACT OF 1974, AS AMENDED ("ERISA"), OR
SECTION 4975 OF THE INTERNAL REVENUE CODE OF 1986, AS AMENDED (THE "CODE"), OR A
GOVERNMENTAL PLAN, AS DEFINED IN SECTION 3(32) OF ERISA, SUBJECT TO ANY FEDERAL,
STATE OR LOCAL LAW WHICH IS, TO A MATERIAL EXTENT, SIMILAR TO THE FOREGOING
PROVISIONS OF ERISA OR THE CODE (COLLECTIVELY, A "PLAN"), AND IS NOT ACTING ON
BEHALF OF OR INVESTING THE ASSETS OF A PLAN OR (B) SUBJECT TO CERTAIN CONDITIONS
SET FORTH IN THE AGREEMENT, THAT THE SOURCE OF FUNDS USED TO PURCHASE THIS
CERTIFICATE IS AN "INSURANCE COMPANY GENERAL ACCOUNT." EACH PERSON WHO ACQUIRES
THIS CERTIFICATE OR ANY INTEREST THEREIN SHALL BE DEEMED TO HAVE MADE THE
REPRESENTATIONS REQUIRED BY THE REPRESENTATION LETTER REFERRED TO IN THE
PRECEDING SENTENCE, UNLESS SUCH PERSON SHALL HAVE PROVIDED SUCH REPRESENTATION
LETTER OR THE OPINION OF COUNSEL REFERRED TO IN SECTION 5.02(C) OF THE AGREEMENT
REFERRED TO HEREIN TO THE MASTER SERVICER AND DEPOSITOR.

<PAGE>

                        MORTGAGE PASS-THROUGH CERTIFICATE
                            SERIES 2007-4, CLASS B-5

   evidencing an interest in a pool of fixed interest rate, monthly pay, first
          lien, one- to four-family residential mortgage loans sold by

                    WELLS FARGO ASSET SECURITIES CORPORATION
               (Not an interest in or obligation of the Depositor)

            THIS CERTIFICATE DOES NOT EVIDENCE AN OBLIGATION OF, OR AN INTEREST
IN, THE DEPOSITOR, THE MASTER SERVICER, THE TRUSTEE OR ANY OF THEIR AFFILIATES,
AND IS NOT INSURED OR GUARANTEED BY THE DEPOSITOR, THE MASTER SERVICER, THE
TRUSTEE OR ANY OF THEIR AFFILIATES, OR BY ANY GOVERNMENT AGENCY OR PRIVATE
INSURER.

            DISTRIBUTIONS IN REDUCTION OF THE PRINCIPAL BALANCE OF THIS
CERTIFICATE WILL BE MADE IN THE MANNER DESCRIBED IN THE AGREEMENT. ACCORDINGLY,
THE OUTSTANDING PRINCIPAL BALANCE OF THIS CERTIFICATE AT ANY TIME MAY BE LESS
THAN THE INITIAL PRINCIPAL BALANCE REPRESENTED HEREBY.

Certificate No.                        Cut-Off Date: March 1, 2007

CUSIP No.: 94985R BD3                  First Distribution Date: April 25, 2007

ISIN No.: US94985RBD35                 Denomination: $

Percentage Interest evidenced          Final Scheduled Maturity Date: April 27,
by this Certificate: %                 2037

<PAGE>

            THIS CERTIFIES THAT ____________________________ is the registered
owner of the Percentage Interest evidenced by this Certificate in monthly
distributions to the Holders of the Class B-5 Certificates with respect to a
Trust Estate consisting of a pool of fixed interest rate, monthly pay, first
lien, one- to four-family residential mortgage loans (the "Mortgage Loans"),
other than the Fixed Retained Yield, if any, with respect thereto, formed by
Wells Fargo Asset Securities Corporation (hereinafter called the "Depositor,"
which term includes any successor entity under the Agreement referred to below).
The Trust Estate was created pursuant to a Pooling and Servicing Agreement dated
as of March 28, 2007 (the "Agreement") among the Depositor, Wells Fargo Bank,
N.A., as master servicer (the "Master Servicer") and HSBC Bank USA, National
Association, as trustee (the "Trustee"), a summary of certain of the pertinent
provisions of which is set forth hereinafter. To the extent not defined herein,
the capitalized terms used herein have the meanings ascribed to such terms in
the Agreement. This Certificate is issued under and is subject to the terms,
provisions and conditions of the Agreement, to which Agreement the Holder of
this Certificate by virtue of the acceptance hereof assents and by which such
Holder is bound.

            Pursuant to the terms of the Agreement, a distribution will be made
on the 25th day of each month or, if such 25th day is not a Business Day, the
Business Day immediately following (the "Distribution Date"), commencing on the
first Distribution Date specified above, to the Person in whose name this
Certificate is registered at the close of business on the Record Date, in an
amount equal to the product of the Percentage Interest evidenced by this
Certificate and, subject to the prior rights of the Class A Certificates and
each Class of Class B Certificates bearing a lower numerical designation as
specified in the Agreement, any Class B-5 Distribution Amount required to be
distributed to Holders of the Class B-5 Certificates on such Distribution Date,
subject to adjustment, in certain events, as specified in the Agreement. The
pass-through rate on the Class B-5 Certificates applicable to each Distribution
Date will be 6.000% per annum. The amount of interest which accrues on this
Certificate in any month will be subject to reduction with respect to any
Non-Supported Interest Shortfall and any Relief Act Shortfall allocated to the
Class B-5 Certificates, as described in the Agreement.

            Distributions on this Certificate will be made by the Paying Agent
by check mailed to the address of the Person entitled thereto, as such name and
address shall appear on the Certificate Register, unless such Person has
notified the Paying Agent pursuant to the Agreement that such payments are to be
made by wire transfer of immediately available funds. Notwithstanding the above,
the final distribution in reduction of the Principal Balance of this Certificate
will be made after due notice of the pendency of such distribution and only upon
presentation and surrender of this Certificate at the office or agency of the
Paying Agent specified for that purpose in the notice of final distribution.

            No transfer of a Class B-5 Certificate will be made unless such
transfer is exempt from the registration requirements of the Securities Act of
1933, as amended, and any applicable state securities laws or is made in
accordance with said Act and laws. In the event that such a transfer is desired
to be made by the Holder hereof, the transferee will be required to execute an
investment letter in the form described in the Agreement. The Holder hereof
desiring to effect such transfer shall, and does hereby agree to, indemnify the
Trustee, the Depositor, the Master Servicer, and any Paying Agent against any
liability that may result if the transfer is not so exempt or is not made in
accordance with such Federal and state laws. The representations required in any
investment letter shall be deemed to have been made in connection with a
transfer of a Class B-5 Certificate that is a Book-Entry Certificate. In
connection with any such transfer, the Master Servicer will also require (i) a
representation letter, in the form as described in the Agreement, stating either
(a) that the transferee is not a Plan and is not acting on behalf of a Plan or
using the assets of a Plan to effect such purchase or (b) subject to certain
conditions described in the Agreement, that the source of funds used to purchase
this Certificate is an "insurance company general account," or (ii) if such
transferee is a Plan, (a) an opinion of counsel acceptable to and in form and
substance satisfactory to the Master Servicer and the Depositor with respect to
certain matters and (b) such other documentation as the Depositor or the Master
Servicer may require, as described in the Agreement. For purposes of clause (i)
of this paragraph, each person who acquires this certificate or any interest
therein shall be deemed to have made the representations required by the
representation letter referred to in the preceding sentence, unless such person
shall have provided such representation letter or the opinion of counsel
referred to in the preceding sentence to the Depositor and Master Servicer.

            Reference is hereby made to the further provisions of this
Certificate set forth on the reverse hereof, which further provisions shall for
all purposes have the same effect as if set forth at this place.

            This Certificate constitutes a "regular interest" in a "real estate
mortgage investment conduit" as those terms are defined in Section 860G(a)(1)
and Section 860D, respectively, of the Internal Revenue Code of 1986, as
amended.

            Unless this Certificate has been countersigned by an authorized
officer of the Authenticating Agent, by manual signature, this Certificate shall
not be entitled to any benefit under the Agreement or be valid for any purpose.

<PAGE>

            IN WITNESS WHEREOF, the Paying Agent has caused this Certificate to
be duly executed as of the date set forth below.

Dated:


                                       Wells Fargo Bank, N.A.,
                                            Paying Agent


                                       By____________________________
                                            Authorized Officer

Countersigned:

Wells Fargo Bank, N.A.,
  Authenticating Agent

By ________________________
   Authorized Officer


<PAGE>

                                   EXHIBIT B-6
                     [FORM OF FACE OF CLASS B-6 CERTIFICATE]

[UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
DEPOSITORY TRUST COMPANY TO THE DEPOSITOR OR ITS AGENT FOR REGISTRATION OF
TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE
NAME OF CEDE & CO. OR SUCH OTHER NAME AS REQUESTED BY AN AUTHORIZED
REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY AND ANY PAYMENT IS MADE TO CEDE &
CO., ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO
ANY PERSON IS WRONGFUL SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN
INTEREST HEREIN.]

THIS CERTIFICATE IS SUBORDINATED IN RIGHT OF PAYMENT TO THE CLASS A
CERTIFICATES, THE CLASS B-1 CERTIFICATES, THE CLASS B-2 CERTIFICATES, THE CLASS
B-3 CERTIFICATES, THE CLASS B-4 CERTIFICATES AND THE CLASS B-5 CERTIFICATES AS
DESCRIBED IN THE AGREEMENT REFERRED TO HEREIN.

THIS CERTIFICATE HAS NOT BEEN AND WILL NOT BE REGISTERED UNDER THE SECURITIES
ACT OF 1933, AS AMENDED, OR THE SECURITIES LAWS OF ANY STATE AND MAY NOT BE
RESOLD OR TRANSFERRED UNLESS IT IS REGISTERED PURSUANT TO SUCH ACT AND LAWS OR
IS SOLD OR TRANSFERRED IN TRANSACTIONS WHICH ARE EXEMPT FROM REGISTRATION UNDER
SUCH ACT AND UNDER APPLICABLE STATE LAW AND IS TRANSFERRED IN ACCORDANCE WITH
THE PROVISIONS OF SECTION 5.02 OF THE AGREEMENT REFERRED TO HEREIN.

THE INITIAL PURCHASER IN THIS CERTIFICATE, AND EACH SUBSEQUENT PURCHASER OF THIS
CERTIFICATE, BY PURCHASING THIS CERTIFICATE OR AN INTEREST HEREIN, IS DEEMED TO
HAVE AGREED TO COMPLY WITH CERTAIN TRANSFER REQUIREMENTS SET FORTH IN THE
POOLING AND SERVICING AGREEMENT REFERRED TO HEREIN.

EXCEPT AS PROVIDED IN SECTION 5.02(C) OF THE AGREEMENT REFERRED TO HEREIN, THIS
CERTIFICATE MAY NOT BE PURCHASED BY OR TRANSFERRED TO ANY PERSON THAT HAS NOT
DELIVERED A REPRESENTATION LETTER STATING EITHER (A) THAT THE TRANSFEREE IS NOT
AN EMPLOYEE BENEFIT PLAN OR OTHER RETIREMENT ARRANGEMENT SUBJECT TO TITLE I OF
THE EMPLOYEE RETIREMENT INCOME SECURITY ACT OF 1974, AS AMENDED ("ERISA"), OR
SECTION 4975 OF THE INTERNAL REVENUE CODE OF 1986, AS AMENDED (THE "CODE"), OR A
GOVERNMENTAL PLAN, AS DEFINED IN SECTION 3(32) OF ERISA, SUBJECT TO ANY FEDERAL,
STATE OR LOCAL LAW WHICH IS, TO A MATERIAL EXTENT, SIMILAR TO THE FOREGOING
PROVISIONS OF ERISA OR THE CODE (COLLECTIVELY, A "PLAN"), AND IS NOT ACTING ON
BEHALF OF OR INVESTING THE ASSETS OF A PLAN OR (B) SUBJECT TO CERTAIN CONDITIONS
SET FORTH IN THE AGREEMENT, THAT THE SOURCE OF FUNDS USED TO PURCHASE THIS
CERTIFICATE IS AN "INSURANCE COMPANY GENERAL ACCOUNT." EACH PERSON WHO ACQUIRES
THIS CERTIFICATE OR ANY INTEREST THEREIN SHALL BE DEEMED TO HAVE MADE THE
REPRESENTATIONS REQUIRED BY THE REPRESENTATION LETTER REFERRED TO IN THE
PRECEDING SENTENCE, UNLESS SUCH PERSON SHALL HAVE PROVIDED SUCH REPRESENTATION
LETTER OR THE OPINION OF COUNSEL REFERRED TO IN SECTION 5.02(C) OF THE AGREEMENT
REFERRED TO HEREIN TO THE MASTER SERVICER AND DEPOSITOR.

<PAGE>

                        MORTGAGE PASS-THROUGH CERTIFICATE
                            SERIES 2007-4, CLASS B-6

   evidencing an interest in a pool of fixed interest rate, monthly pay, one-
                to four-family residential mortgage loans sold by

                    WELLS FARGO ASSET SECURITIES CORPORATION
               (Not an interest in or obligation of the Depositor)

            THIS CERTIFICATE DOES NOT EVIDENCE AN OBLIGATION OF, OR AN INTEREST
IN, THE DEPOSITOR, THE MASTER SERVICER, THE TRUSTEE OR ANY OF THEIR AFFILIATES,
AND IS NOT INSURED OR GUARANTEED BY THE DEPOSITOR, THE MASTER SERVICER, THE
TRUSTEE OR ANY OF THEIR AFFILIATES, OR BY ANY GOVERNMENT AGENCY OR PRIVATE
INSURER.

            DISTRIBUTIONS IN REDUCTION OF THE PRINCIPAL BALANCE OF THIS
CERTIFICATE WILL BE MADE IN THE MANNER DESCRIBED IN THE AGREEMENT. ACCORDINGLY,
THE OUTSTANDING PRINCIPAL BALANCE OF THIS CERTIFICATE AT ANY TIME MAY BE LESS
THAN THE INITIAL PRINCIPAL BALANCE REPRESENTED HEREBY.

Certificate No.                        Cut-Off Date: March 1, 2007

CUSIP No.: 94985R BE1                  First Distribution Date: April 25, 2007

ISIN No.: US94985RBE18                 Denomination: $

Percentage Interest evidenced          Final Scheduled Maturity Date: April 27,
by this Certificate: %                 2037

<PAGE>

            THIS CERTIFIES THAT ____________________________ is the registered
owner of the Percentage Interest evidenced by this Certificate in monthly
distributions to the Holders of the Class B-6 Certificates with respect to a
Trust Estate consisting of a pool of fixed interest rate, monthly pay, first
lien, one- to four-family residential mortgage loans (the "Mortgage Loans"),
other than the Fixed Retained Yield, if any, with respect thereto, formed by
Wells Fargo Asset Securities Corporation (hereinafter called the "Depositor,"
which term includes any successor entity under the Agreement referred to below).
The Trust Estate was created pursuant to a Pooling and Servicing Agreement dated
as of March 28, 2007 (the "Agreement") among the Depositor, Wells Fargo Bank,
N.A., as master servicer (the "Master Servicer") and HSBC Bank USA, National
Association, as trustee (the "Trustee"), a summary of certain of the pertinent
provisions of which is set forth hereinafter. To the extent not defined herein,
the capitalized terms used herein have the meanings ascribed to such terms in
the Agreement. This Certificate is issued under and is subject to the terms,
provisions and conditions of the Agreement, to which Agreement the Holder of
this Certificate by virtue of the acceptance hereof assents and by which such
Holder is bound.

            Pursuant to the terms of the Agreement, a distribution will be made
on the 25th day of each month or, if such 25th day is not a Business Day, the
Business Day immediately following (the "Distribution Date"), commencing on the
first Distribution Date specified above, to the Person in whose name this
Certificate is registered at the close of business on the Record Date, in an
amount equal to the product of the Percentage Interest evidenced by this
Certificate and, subject to the prior rights of the Class A Certificates and
each Class of Class B Certificates bearing a lower numerical designation as
specified in the Agreement, any Class B-6 Distribution Amount required to be
distributed to Holders of the Class B-6 Certificates on such Distribution Date,
subject to adjustment, in certain events, as specified in the Agreement. The
pass-through rate on the Class B-6 Certificates applicable to each Distribution
Date will be 6.000% per annum. The amount of interest which accrues on this
Certificate in any month will be subject to reduction with respect to any
Non-Supported Interest Shortfall and any Relief Act Shortfall allocated to the
Class B-6 Certificates, as described in the Agreement.

            Distributions on this Certificate will be made by the Paying Agent
by check mailed to the address of the Person entitled thereto, as such name and
address shall appear on the Certificate Register, unless such Person has
notified the Paying Agent pursuant to the Agreement that such payments are to be
made by wire transfer of immediately available funds. Notwithstanding the above,
the final distribution in reduction of the Principal Balance of this Certificate
will be made after due notice of the pendency of such distribution and only upon
presentation and surrender of this Certificate at the office or agency of the
Paying Agent specified for that purpose in the notice of final distribution.

            No transfer of a Class B-6 Certificate will be made unless such
transfer is exempt from the registration requirements of the Securities Act of
1933, as amended, and any applicable state securities laws or is made in
accordance with said Act and laws. In the event that such a transfer is desired
to be made by the Holder hereof, the transferee will be required to execute an
investment letter in the form described in the Agreement. The Holder hereof
desiring to effect such transfer shall, and does hereby agree to, indemnify the
Trustee, the Depositor, the Master Servicer, and any Paying Agent against any
liability that may result if the transfer is not so exempt or is not made in
accordance with such Federal and state laws. The representations required in any
investment letter shall be deemed to have been made in connection with a
transfer of a Class B-6 Certificate that is a Book-Entry Certificate. In
connection with any such transfer, the Master Servicer will also require (i) a
representation letter, in the form as described in the Agreement, stating either
(a) that the transferee is not a Plan and is not acting on behalf of a Plan or
using the assets of a Plan to effect such purchase or (b) subject to certain
conditions described in the Agreement, that the source of funds used to purchase
this Certificate is an "insurance company general account," or (ii) if such
transferee is a Plan, (a) an opinion of counsel acceptable to and in form and
substance satisfactory to the Master Servicer and the Depositor with respect to
certain matters and (b) such other documentation as the Depositor or the Master
Servicer may require, as described in the Agreement. For purposes of clause (i)
of this paragraph, each person who acquires this certificate or any interest
therein shall be deemed to have made the representations required by the
representation letter referred to in the preceding sentence, unless such person
shall have provided such representation letter or the opinion of counsel
referred to in the preceding sentence to the Depositor and Master Servicer.

            Reference is hereby made to the further provisions of this
Certificate set forth on the reverse hereof, which further provisions shall for
all purposes have the same effect as if set forth at this place.

            This Certificate constitutes a "regular interest" in a "real estate
mortgage investment conduit" as those terms are defined in Section 860G(a)(1)
and Section 860D, respectively, of the Internal Revenue Code of 1986, as
amended.

            Unless this Certificate has been countersigned by an authorized
officer of the Authenticating Agent, by manual signature, this Certificate shall
not be entitled to any benefit under the Agreement or be valid for any purpose.

<PAGE>

            IN WITNESS WHEREOF, the Paying Agent has caused this Certificate to
be duly executed as of the date set forth below.

Dated:


                                       Wells Fargo Bank, N.A.,
                                            Paying Agent


                                       By____________________________
                                            Authorized Officer

Countersigned:

Wells Fargo Bank, N.A.,
  Authenticating Agent

By ________________________
   Authorized Officer

<PAGE>

                                    EXHIBIT C

                 [Form of Reverse of Series 2007-4 Certificates]

                    WELLS FARGO ASSET SECURITIES CORPORATION
                       MORTGAGE PASS-THROUGH CERTIFICATES
                                  SERIES 2007-4

            This Certificate is one of a duly authorized issue of Certificates
issued in several Classes designated as Mortgage Pass-Through Certificates of
the Series specified hereon (herein collectively called the "Certificates").

            The Certificates are limited in right of payment to certain
collections and recoveries respecting the Mortgage Loans, all as more
specifically set forth herein and in the Agreement. In the event funds are
advanced with respect to any Mortgage Loan by a Servicer, the Master Servicer or
the Trustee, such advances are reimbursable to such Servicer, the Master
Servicer or the Trustee to the extent provided in the Agreement, from related
recoveries on such Mortgage Loan or from other cash that would have been
distributable to Certificateholders.

            As provided in the Agreement, withdrawals from the Certificate
Account created for the benefit of Certificateholders may be made by the Master
Servicer from time to time for purposes other than distributions to
Certificateholders, such purposes including reimbursement to a Servicer, the
Master Servicer or the Trustee, as applicable, of advances made by such
Servicer, the Master Servicer or the Trustee.

            The Agreement permits, with certain exceptions therein provided, the
amendment of the Agreement and the modification of the rights and obligations of
the Depositor, the Master Servicer and the Trustee and the rights of the
Certificateholders under the Agreement at any time by the Depositor, the Master
Servicer and the Trustee with the consent of the Holders of Certificates
evidencing in the aggregate not less than 66 2/3% of the Voting Interests of
each Class of Certificates affected thereby. Any such consent by the Holder of
this Certificate shall be conclusive and binding on such Holder and upon all
future holders of this Certificate and of any Certificate issued upon the
transfer hereof or in exchange hereof or in lieu hereof whether or not notation
of such consent is made upon the Certificate. The Agreement also permits the
amendment thereof in certain circumstances without the consent of the Holders of
any of the Certificates.

            As provided in the Agreement and subject to certain limitations
therein set forth, the transfer of this Certificate is registrable in the
Certificate Register upon surrender of this Certificate for registration of
transfer at the office or agency maintained by the Certificate Registrar, duly
endorsed by, or accompanied by an assignment in the form below or other written
instrument of transfer in form satisfactory to the Certificate Registrar, duly
executed by the Holder hereof or such Holder's attorney duly authorized in
writing, and thereupon one or more new Certificates of authorized Denominations
evidencing the same Class and aggregate Percentage Interest will be issued to
the designated transferee or transferees.

            The Certificates are issuable only as registered Certificates
without coupons in Classes and Denominations specified in the Agreement. As
provided in the Agreement and subject to certain limitations therein set forth,
Certificates are exchangeable for new Certificates of authorized Denominations
evidencing the same Class and aggregate Percentage Interest, as requested by the
Holder surrendering the same.

            No service charge will be made for any such registration of transfer
or exchange, but the Certificate Registrar may require payment of a sum
sufficient to cover any tax or other governmental charge payable in connection
therewith.

            The Depositor, the Master Servicer, the Trustee, the Paying Agent
and the Certificate Registrar, and any agent of the Depositor, the Master
Servicer, the Trustee, the Paying Agent or the Certificate Registrar, may treat
the Person in whose name this Certificate is registered as the owner hereof for
all purposes, and neither the Depositor, the Master Servicer, the Trustee, the
Certificate Registrar nor any such agent shall be affected by notice to the
contrary.

            The obligations created by the Agreement in respect of the
Certificates and the Trust Estate created thereby shall terminate upon the last
action required to be taken by the Paying Agent on the Final Distribution Date
pursuant to the Agreement following the earlier of (i) the payment or other
liquidation (or advance with respect thereto) of the last Mortgage Loan subject
thereto or the disposition of all property acquired upon foreclosure or deed in
lieu of foreclosure of any Mortgage Loan, and (ii) the purchase by the Depositor
from the Trust Estate of all remaining Mortgage Loans and all property acquired
in respect of such Mortgage Loans; provided, however, that the Trust Estate will
in no event continue beyond the expiration of 21 years from the death of the
last survivor of the descendants of Joseph P. Kennedy, the late ambassador of
the United States to the Court of St. James, living on the date of the
Agreement. The Agreement permits, but does not require, the Depositor to
purchase all remaining Mortgage Loans and all property acquired in respect of
any Mortgage Loan at a price determined as provided in the Agreement. The
exercise of such option will effect early retirement of the Certificates, the
Depositor's right to exercise such option being subject to the Pool Scheduled
Principal Balance of the Mortgage Loans as of the Distribution Date upon which
the proceeds of such repurchase are distributed being less than ten percent of
the Cut-Off Date Aggregate Principal Balance.

<PAGE>

                                   ASSIGNMENT

FOR VALUE RECEIVED, the undersigned hereby sell(s), assign(s) and transfer(s)
unto __________________________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
    (Please print or typewrite name and address including postal zip code of
                                    assignee)

the beneficial interest evidenced by the within Mortgage Pass-Through
Certificate and hereby authorizes the transfer of registration of such interest
to assignee on the Certificate Register of the Trust Estate.

            I (We) further direct the Certificate Registrar to issue a new
Certificate of a like Denomination or Percentage Interest and Class, to the
above named assignee and deliver such Certificate to the following address:

_______________________________________________________________________________
_______________________________________________________________________________

Social Security or other Identifying Number of Assignee:

Dated:


                                       -----------------------------------------
                                          Signature by or on behalf of assignor



                                       -----------------------------------------
                                          Signature Guaranteed

<PAGE>

                            DISTRIBUTION INSTRUCTIONS

            The assignee should include the following for purposes of
distribution:

            Distributions shall be made by wire transfer or otherwise, in
immediately available funds to _________________________________________________
for the account of ____________________________________________________ account
number _____________, or, if mailed by check, to _______________________________
_______________________________________________________. Applicable statements
should be mailed to ____________________________________________________________
_______________.

            This information is provided by ______________________, the assignee
named above, or ___________________________________, as its agent.

<PAGE>

                                    EXHIBIT D

                                    RESERVED


<PAGE>

                                    EXHIBIT E


                               CUSTODIAL AGREEMENT

            THIS CUSTODIAL AGREEMENT (as amended and supplemented from time to
time, the "Agreement"), dated as of March 28, 2007, by and among HSBC BANK USA,
NATIONAL ASSOCIATION, not individually, but solely as Trustee (including its
successors under the Pooling and Servicing Agreement defined below, the
"Trustee"), WELLS FARGO ASSET SECURITIES CORPORATION (together with any
successor in interest, the "Depositor"), WELLS FARGO BANK, N.A. (together with
any successor in interest or successor under the Pooling and Servicing Agreement
referred to below, the "Master Servicer") and WELLS FARGO BANK, N.A. (together
with any successor in interest or any successor appointed hereunder, the
"Custodian").

                           W I T N E S S E T H  T H A T

            WHEREAS, the Depositor, the Master Servicer, and the Trustee, have
entered into a Pooling and Servicing Agreement dated as of March 28, 2007
relating to the issuance of Mortgage Pass-Through Certificates, Series 2007-4
(as amended and supplemented from time to time, the "Pooling and Servicing
Agreement"); and

            WHEREAS, the Custodian has agreed to act as agent for the Trustee
for the purposes of receiving and holding certain documents and other
instruments delivered by the Depositor under the Pooling and Servicing
Agreement, all upon the terms and conditions and subject to the limitations
hereinafter set forth;

            NOW, THEREFORE, in consideration of the premises and the mutual
covenants and agreements hereinafter set forth, the Trustee, the Depositor, the
Master Servicer and the Custodian hereby agree as follows:

                                    ARTICLE I

                                   Definitions

            Capitalized terms used in this Agreement and not defined herein
shall have the meanings assigned in the Pooling and Servicing Agreement, unless
otherwise required by the context herein.

                                   ARTICLE II

                          Custody of Mortgage Documents

            Section 2.1. Custodian to Act as Agent; Acceptance of Custodial
Files. Subject to Section 2.3 hereof, the Custodian, as the duly appointed agent
of the Trustee for these purposes, declares that it holds and will hold the
documents delivered to it pursuant to Section 2.01 of the Pooling and Servicing
Agreement and any other documents constituting part of the Owner Mortgage Loan
File or Retained Mortgage Loan File received on or subsequent to the date hereof
(the "Custodial Files") as agent for the Trustee, in trust, for the use and
benefit of all present and future Certificateholders. The Depositor shall give
written notice to the Custodian within 10 business days of the occurrence of a
Document Transfer Event.

            Section 2.2. Recordation of Assignments. Unless an assignment of a
Mortgage is not required to be recorded in accordance with Section 2.01 of the
Pooling and Servicing Agreement, if any Custodial File includes one or more
assignments to the Trustee of Mortgage Notes that have not been recorded, each
such assignment shall be delivered by the Custodian to the Depositor for the
purpose of recording it in the appropriate public office for real property
records, and the Depositor, at no expense to the Custodian, shall promptly cause
to be recorded in the appropriate public office for real property records each
such assignment and, upon receipt thereof from such public office, shall return
each such assignment to the Custodian.

            Section 2.3. Review of Custodial Files. The Custodian agrees, for
the benefit of Certificateholders, to review, in accordance with the provisions
of Section 2.02 of the Pooling and Servicing Agreement, each Custodial File and
to provide the initial and final certifications in the forms of Exhibits N and O
to the Pooling and Servicing Agreement in accordance with the provisions
thereof. If in performing the review required by this Section 2.3 the Custodian
finds any document or documents constituting a part of a Custodial File to be
missing or defective, the Custodian shall follow the procedures specified in the
Pooling and Servicing Agreement.

            Section 2.4. Notification of Breaches of Representations and
Warranties. Upon discovery by the Custodian of a breach of any representation or
warranty made by the Depositor or the Master Servicer as set forth in the
Pooling and Servicing Agreement, the Custodian shall follow the procedures
specified in the Pooling and Servicing Agreement.

            Section 2.5. Custodian to Cooperate; Release of Custodial Files.
Upon the payment in full of any Mortgage Loan, or the receipt by the Master
Servicer of a notification that payment in full will be escrowed in a manner
customary for such purposes, the Master Servicer or applicable Servicer shall
immediately deliver to the Custodian two copies of a Request for Release or such
request in an electronic format acceptable to the Custodian and shall request
delivery to it of the Custodial File. The Custodian agrees, within five business
days of receipt of such Request for Release, to release the related Custodial
File to the Master Servicer or applicable Servicer.

            From time to time as is appropriate for the servicing or foreclosure
of any Mortgage Loan, the Master Servicer or applicable Servicer shall deliver
to the Custodian two copies of a Request for Release of a Servicing Officer
requesting that possession of the Custodial File be released to the Servicer or
Master Servicer and certifying as to the reason for such release. Upon receipt
of the foregoing, the Custodian shall deliver the Custodial File to the Master
Servicer or applicable Servicer. The Master Servicer or applicable Servicer
shall cause each Custodial File therein so released to be returned to the
Custodian when the need therefor by the Master Servicer or applicable Servicer
no longer exists, unless (i) the Mortgage Loan has been liquidated and the
Liquidation Proceeds relating to the Mortgage Loan have been deposited in the
Certificate Account to the extent required by the Pooling and Servicing
Agreement or (ii) the Custodial File or such document has been delivered to an
attorney, or to a public trustee or other public official as required by law,
for purposes of initiating or pursuing legal action or other proceedings for the
foreclosure of the Mortgaged Property either judicially or non-judicially. In
the event of the liquidation of a Mortgage Loan, the Master Servicer or
applicable Servicer shall deliver two copies of a Request for Release with
respect thereto to the Custodian upon deposit of the related Liquidation
Proceeds in the Certificate Account to the extent required by the Pooling and
Servicing Agreement.

            The Custodian shall maintain records (i) identifying all requests
made by Servicers or the Master Servicer (other than requests relating to
Custodial Files already released by the Custodian) for the release by the
Custodian of Custodial Files with respect to the Mortgage Loans and (ii) all
Custodial Files released by the Custodian.

            Section 2.6. Assumption Agreements. In the event that any assumption
agreement or substitution of liability agreement is entered into with respect to
any Mortgage Loan subject to this Agreement in accordance with the terms and
provisions of the Pooling and Servicing Agreement, the Master Servicer shall
notify the Custodian that such assumption or substitution agreement has been
completed by forwarding to the Custodian the original of such assumption or
substitution agreement, which copy shall be added to the related Custodial File
and, for all purposes, shall be considered a part of such Custodial File to the
same extent as all other documents and instruments constituting parts thereof.

                                   ARTICLE III

                            Concerning the Custodian

            Section 3.1. Custodian a Bailee and Agent of the Trustee. With
respect to each Mortgage Note, Mortgage and other documents constituting each
Custodial File which are delivered to the Custodian, the Custodian is
exclusively the bailee and agent of the Trustee, holds such documents for the
benefit of Certificateholders and undertakes to perform such duties and only
such duties as are specifically set forth in this Agreement and in the Pooling
and Servicing Agreement. All provisions of the Pooling and Servicing Agreement
setting forth duties of the Custodian in more detail are hereby incorporated by
reference into this Agreement. Except upon compliance with the provisions of
Section 2.5 of this Agreement and the provisions of the Pooling and Servicing
Agreement, no Mortgage Note or other document constituting a part of a Custodial
File shall be delivered by the Custodian to the Depositor or the Master Servicer
or otherwise released from the possession of the Custodian.

            Section 3.2. Indemnification. The Depositor hereby agrees to
indemnify and hold the Custodian harmless from and against all claims,
liabilities, losses, actions, suits or proceedings at law or in equity, or any
other expenses, fees or charges of any character or nature, which the Custodian
may incur or with which the Custodian may be threatened by reasons of its acting
as custodian under this Agreement, including indemnification of the Custodian
against any and all expenses, including attorney's fees if counsel for the
Custodian has been approved by the Depositor, and the cost of defending any
action, suit or proceedings or resisting any claim. Notwithstanding the
foregoing, it is specifically understood and agreed that in the event any such
claim, liability, loss, action, suit or proceeding or other expense, fees, or
charge shall have been caused by reason of any negligent act, negligent failure
to act, or willful misconduct on the part of the Custodian, or which shall
constitute a willful breach of its duties hereunder, the indemnification
provisions of this Agreement shall not apply.

            Section 3.3. Custodian May Own Certificates. The Custodian in its
individual or any other capacity may become the owner or pledgee of Certificates
with the same rights it would have if it were not Custodian.

            Section 3.4. Master Servicer to Pay Custodian's Fees and Expenses.
The Master Servicer covenants and agrees to pay to the Custodian from time to
time, and the Custodian shall be entitled to, reasonable compensation for all
services rendered by it in the exercise and performance of any of the powers and
duties hereunder of the Custodian, and the Master Servicer will pay or reimburse
the Custodian upon its request for all reasonable expenses, disbursements and
advances incurred or made by the Custodian in accordance with any of the
provisions of this Agreement (including the reasonable compensation and the
expenses and disbursements of its counsel and of all persons not regularly in
its employ), except any such expense, disbursement or advance as may arise from
its negligence or bad faith. The Master Servicer's obligations regarding
payments due to the Custodian pursuant to this Section 3.4 shall survive the
termination of this Agreement with respect to any fees and expenses due
hereunder.

            Section 3.5. Custodian May Resign; Trustee May Remove Custodian. The
Custodian, upon 30 days written notice to the Depositor, the Master Servicer and
the Trustee, may resign from the obligations and duties hereby imposed upon it
as such obligations and duties relate to its acting as Custodian of the Mortgage
Loans. Upon receiving such notice of resignation, the Trustee shall either take
custody of the Custodial Files itself and give prompt notice thereof to the
Depositor, the Master Servicer and the Custodian or promptly appoint a successor
Custodian by written instrument, in duplicate, one copy of which instrument
shall be delivered to the resigning Custodian and one copy to the successor
Custodian. If the Trustee shall not have taken custody of the Custodial Files
and no successor Custodian shall have been so appointed and have accepted
resignation, the resigning Custodian may petition any court of competent
jurisdiction for the appointment of a successor Custodian.

            The Trustee, upon 60 days written notice to the Depositor, the
Master Servicer and the Custodian, may remove the Custodian. In such event, the
Trustee shall appoint, or petition a court of competent jurisdiction to appoint,
a successor Custodian hereunder. Any successor Custodian shall be a depository
institution subject to supervision or examination by federal or state authority
and shall be able to satisfy the other requirements contained in Section 3.7.

            Any resignation or removal of the Custodian and appointment of a
successor Custodian pursuant to any of the provisions of this Section 3.5 shall
become effective upon acceptance of appointment by the successor Custodian. The
Trustee shall give prompt notice to the Depositor and the Master Servicer of the
appointment of any successor Custodian. No successor Custodian shall have been
appointed and accepted appointment by the Trustee without the prior approval of
the Depositor and the Master Servicer.

            Section 3.6. Merger or Consolidation of Custodian. Any Person into
which the Custodian may be merged or converted or with which it may be
consolidated, or any Person resulting from any merger, conversion or
consolidation to which the Custodian shall be a party, or any Person succeeding
to the business of the Custodian, shall be the successor of the Custodian
hereunder, without the execution or filing of any paper or any further act on
the part of any of the parties hereto, anything herein to the contrary
notwithstanding.

            The Custodian and such successor or surviving Person shall notify
the Depositor, the Master Servicer and the Trustee of any such merger,
conversion or consolidation at least two Business Days prior to the effective
date thereof and shall provide the Depositor and the Master Servicer with all
information required by the Depositor to comply with its reporting obligations
not later than the effective date of such merger, conversion or consolidation
(unless giving prior notice would be prohibited by applicable law or by a
confidentiality agreement, in which case notice shall be given by 12 noon
eastern time one Business Day after such merger or consolidation).

            Section 3.7. Representations of the Custodian. The Custodian hereby
represents that it is a depository institution subject to supervision or
examination by a federal or state authority, has a combined capital and surplus
of at least $10,000,000 and is qualified to do business in the jurisdiction in
which it will hold any Custodial File.

            Section 3.8.      Limitations  on  the  Responsibilities  of  the
Custodian.

            (a) Neither the Custodian nor any of its Affiliates, directors,
officers, agents, counsel, attorneys-in-fact, and employees shall be liable for
any action or omission to act hereunder except for its own or such person's
gross negligence or willful misconduct. Notwithstanding the foregoing sentence,
in no event shall the Custodian or its Affiliates, directors, officers, agents,
counsel, attorneys-in-fact, and employees be held liable for any special,
indirect, punitive or consequential damages resulting from any action taken or
omitted to be taken by it or them hereunder or in connection herewith even if
advised of the possibility of such damages. The provisions of this Section 3.8
shall survive the resignation or removal of the Custodian and the termination of
this Agreement.

            (b) The Custodian shall not be responsible for preparing or filing
any reports or returns relating to federal, state or local income taxes with
respect to this Agreement, other than for the Custodian's compensation or for
reimbursement of expenses.

            (c) The Custodian shall not be responsible or liable for, and makes
no representation or warranty with respect to, the validity, adequacy or
perfection of any lien upon or security interest in any Mortgage File.

            (d) The Custodian shall not be responsible for delays or failures in
performance resulting from acts beyond its control. Such acts shall include, but
not be limited to, acts of God, strikes, lockouts, riots, acts of war or
terrorism, epidemics, nationalization, expropriation, currency restrictions,
governmental regulations superimposed after the fact, fire, communication line
failures, computer viruses, power failures, earthquakes or other disasters.

            (e) The duties and obligations of the Custodian shall only be such
as are expressly set forth in this Agreement and the Pooling and Servicing
Agreement or as set forth in a written amendment to this Agreement or the
Pooling and Servicing Agreement executed by the parties hereto or their
successors and assigns. In the event that any provision of this Agreement
implies or requires that action or forbearance be taken by a party, but is
silent as to which party has the duty to act or refrain from acting, the parties
agree that the Custodian shall not be the party required to take the action or
refrain from acting. In no event shall the Custodian have any responsibility to
ascertain or take action except as expressly provided herein.

            (f) Nothing in this Agreement shall be deemed to impose on the
Custodian any duty to qualify to do business in any jurisdiction, other than (i)
any jurisdiction where any Mortgage File is or may be held by the Custodian from
time to time hereunder, and (ii) any jurisdiction where its ownership of
property or conduct of business requires such qualification and where failure to
qualify could have a material adverse effect on the Custodian or its property or
business or on the ability of the Custodian to perform it duties hereunder.

            (g) The Custodian shall have no duty to ascertain whether or not any
cash amount or payment has been received by the Trustee, the Depositor, the
Master Servicer, or any third person.

                                   ARTICLE IV

           Documents and Notices Required to be Delivered by Custodian

            Section 4.1 Assessment of Servicing Compliance; Registered Public
Accounting Firm Attestation Reports; Exchange Act Reporting. (a) The Custodian
shall furnish, or cause to be furnished in the case of clause (iii), to the
Master Servicer, no later than March 5 of each year or if such day is not a
Business Day, the next Business Day (with a 10 calendar day cure period, but in
no event later than March 15), commencing in March 2008, the following:

            (i) a report (in form and substance reasonably satisfactory to the
      Master Servicer and the Depositor) regarding the Custodian's assessment of
      compliance with the Servicing Criteria applicable to it during the
      immediately preceding calendar year, as required under Rules 13a-18 and
      15d-18 of the Exchange Act and Item 1122 of Regulation AB. Such report
      shall be addressed to the Master Servicer and signed by an authorized
      officer of the Custodian, and shall address, at a minimum, each of the
      Servicing Criteria applicable to the Custodian, as specified in the table
      in Exhibit R to the Pooling and Servicing Agreement;

            (ii) a report of a registered public accounting firm reasonably
      acceptable to the Master Servicer and the Depositor that attests to, and
      reports on, the assessment of compliance made by the Custodian and
      delivered pursuant to the preceding paragraph. Such attestation shall be
      in accordance with Rules 1-02(a)(3) and 2-02(g) of Regulation S-X under
      the Securities Act and the Exchange Act. If requested by the Master
      Servicer or the Depositor, such report shall contain or be accompanied by
      a consent of such accounting firm to inclusion or incorporation of such
      report in the Depositor's Registration Statement on Form S-3 relating to
      the Certificates and the Trust's Form 10-K; and

            (iii) an assessment of compliance and accountants' attestation as
      described in paragraphs (i) and (ii) of this Section 4.1(a) with respect
      to each Subcontractor determined by the Custodian pursuant to Section 4.2
      to be "participating in the servicing function" within the meaning of Item
      1122 of Regulation AB.

            An assessment of compliance provided by a Subcontractor pursuant to
Section 4.1(a)(iii) need not address any elements of the Servicing Criteria
applicable to it other than those specified by the Custodian pursuant to Section
4.2.

            No later than 30 days following the end of each fiscal year for the
Trust for which a Form 10-K is required to be filed, the Custodian shall forward
to the Master Servicer the name of each Subcontractor engaged by it and what
Relevant Servicing Criteria will be addressed in the report on assessment of
compliance prepared by such Subcontractor. When the Custodian submits its
assessment to the Master Servicer, it will also at such time include the
assessment (and attestation pursuant to Section 4.1(a)(ii) hereof) of each
Subcontractor engaged by it.

            (b) Within five (5) calendar days after a Distribution Date, the
Custodian shall provide to the Master Servicer, to the extent known, in
EDGAR-compatible format, or in such other form as otherwise agreed upon by the
Master Servicer and the Custodian, the form and substance of any Additional Form
10-D Disclosure applicable to the Custodian, as indicated in the table in
Exhibit S to the Pooling and Servicing Agreement. The Custodian acknowledges
that the performance by the Master Servicer of its duties under Section 3.12(a)
of the Pooling and Servicing Agreement relating to the timely preparation and
filing of Form 10-D is contingent upon the Custodian strictly observing all
applicable deadlines in the performance of its duties under this Section 4.1(b).

            (c) No later than March 5 (with a 10 calendar day cure period, but
in no event later than March 15) of each year that the Trust is subject to the
Exchange Act reporting requirements, commencing in March 2008, the Custodian
shall provide to the Master Servicer, to the extent known, in EDGAR-compatible
format, or in such other form as otherwise agreed upon by the Master Servicer
and the Custodian, the form and substance of any Additional Form 10-K Disclosure
applicable to the Custodian, as indicated in the table in Exhibit T to the
Pooling and Servicing Agreement. The Custodian acknowledges that the performance
by the Master Servicer of its duties under Section 3.12(b) of the Pooling and
Servicing Agreement relating to the timely preparation and filing of Form 10-K
is contingent upon the Custodian strictly observing all applicable deadlines in
the performance of its duties under this Section 4.1(c).

            (d) For so long as the Trust is subject to the Exchange Act
reporting requirements, no later than the end of business on the second Business
Day after the occurrence of a Reportable Event applicable to the Custodian, the
Custodian shall provide to the Master Servicer, to the extent known, in
EDGAR-compatible format, or in such other form as otherwise agreed upon by the
Master Servicer and the Custodian, the form and substance of any Form 8-K
Disclosure Information applicable to the Custodian, as indicated in the table in
Exhibit U to the Pooling and Servicing Agreement. The Custodian acknowledges
that the performance by the Master Servicer of its duties under Section 3.12(c)
of the Pooling and Servicing Agreement relating to the timely preparation and
filing of Form 8-K is contingent upon the Custodian strictly observing all
applicable deadlines in the performance of its duties under this Section 4.1(d).

            (e) The Custodian shall indemnify the Master Servicer, each
affiliate of the Master Servicer, the Trust, each broker dealer acting as
underwriter or initial purchaser of the Certificates, each Person who controls
any of such parties and the Depositor (within the meaning of Section 15 of the
Securities Act and Section 20 of the Exchange Act); and the respective present
and former directors, officers, employees and agents of each of the foregoing
and of the Depositor (each such entity, an "Indemnified Party"), and shall hold
each of them harmless from and against any losses, damages, penalties, fines,
forfeitures, legal fees and expenses and related costs, judgments, and any other
costs, fees and expenses that any of them may sustain arising out of or based
upon:

                  (i) (A) any untrue statement of a material fact contained or
            alleged to be contained in any information, report, certification,
            accountants' letter or other material provided in written or
            electronic form under this Section 4.1 or Section 4.2 hereof by or
            on behalf of the Custodian, or provided under Sections 4.1 or 4.2 by
            or on behalf of any Subcontractor (collectively, the "Custodian
            Information"), or (B) the omission or alleged omission to state in
            the Custodian Information a material fact required to be stated in
            the Custodian Information or necessary in order to make the
            statements therein, in the light of the circumstances under which
            they were made, not misleading; provided, by way of clarification,
            that clause (B) of this paragraph shall be construed solely by
            reference to the Custodian Information and not to any other
            information communicated in connection with a sale or purchase of
            securities, without regard to whether the Custodian Information or
            any portion thereof is presented together with or separately from
            such other information; or

                  (ii) any failure by the Custodian or any Subcontractor engaged
            by the Custodian to deliver any information, report, certification,
            accountants' letter or other material when and as required under
            Sections 4.1 or 4.2, including any failure by the Custodian to
            identify pursuant to Section 4.2 any Subcontractor "participating in
            the servicing function" within the meaning of Item 1122 of
            Regulation AB.

      In the case of any failure of performance described in clause (ii) of this
Section, the Custodian shall promptly reimburse the Master Servicer and the
Depositor, as applicable, for all costs reasonably incurred by each such party
in order to obtain the information, report, certification, accountants' letter
or other material not delivered as required by the Custodian or any
Subcontractor. If the indemnification provided for herein is unavailable to hold
harmless any Indemnified Party, then the Custodian agrees that it shall
contribute to the amount paid or payable by such Indemnified Party as a result
of the losses, claims, damages or liabilities of such Indemnified Party in such
proportion as is appropriate to reflect the relative fault of such Indemnified
Party on the one hand and the Custodian on the other in connection with a breach
of the Custodian's obligations under this Section 4.1 or the Custodian's
negligence, bad faith or willful misconduct in connection therewith.

            4.2 Engagement of Affiliates or Third-Parties. The Custodian shall
not hire or otherwise utilize the services of any Subcontractor to fulfill any
of the obligations of the Custodian as servicer under this Agreement unless the
Custodian complies with the provisions of this Section.

            It shall not be necessary for the Custodian to seek the consent of
the Master Servicer or the Depositor to the utilization of any Subcontractor.
The Custodian shall promptly upon request provide to the Master Servicer (or any
designee of Master Servicer) a written description (in form and substance
satisfactory to the Master Servicer and the Depositor) of the role and function
of each Subcontractor utilized by the Custodian, specifying (i) the identity of
each such Subcontractor, (ii) which (if any) of such Subcontractors are
"participating in the servicing function" within the meaning of Item 1122 of
Regulation AB, and (iii) which elements of the Servicing Criteria will be
addressed in assessments of compliance provided by each Subcontractor identified
pursuant to clause (ii) of this paragraph.

            As a condition to the utilization of any Subcontractor determined to
be "participating in the servicing function" within the meaning of Item 1122 of
Regulation AB, the Custodian shall cause any such Subcontractor used by the
Custodian, for the benefit of the Master Servicer and the Depositor to comply
with the provisions of Section 4.1 of this Agreement to the same extent as if
such Subcontractor were the Custodian. The Custodian shall be responsible for
obtaining from each Subcontractor and delivering to the Master Servicer any
assessment of compliance and attestation required to be delivered by such
Subcontractor under Section 4.1, in each case as and when required to be
delivered.

            4.3 Errors and Omissions Policy. The Custodian shall maintain, at
all times and at its own expense, an insurance policy covering losses caused by
errors or omissions of the Custodian and its personnel (such policy, an "Errors
and Omissions Policy"), which policy shall have such terms and coverage amounts
as are comparable to those of errors and omissions policies maintained by
custodians of mortgage loans generally.

            The Errors and Omissions Policy shall insure the Custodian, its
successors and assigns, against any losses resulting from negligence, errors or
omissions on the part of officers, employees or other persons acting on behalf
of the Custodian in the performance of its duties as Custodian pursuant to this
Agreement.

            The Custodian shall maintain in effect the Errors and Omissions
Policy at all times and the Errors and Omissions Policy may not be canceled,
permitted to lapse or otherwise terminated without the acquisition of comparable
coverage by the Custodian.

            4.4 Compliance with Article IV. If (a) the Custodian fails to comply
with its obligations to deliver any assessment of servicing compliance or
registered public accounting firm attestation reports required pursuant to this
Article IV or (b) any Subcontractor engaged by the Custodian fails to comply
with its obligations to deliver any assessment of servicing compliance or
registered public accounting firm attestation reports, the Master Servicer, may,
after consultation with the Depositor, remove the Custodian and appoint a
successor custodian by written instrument, in duplicate, one copy of which
instrument shall be delivered to the Custodian so removed and one copy to the
successor custodian.

                                    ARTICLE V

                            Miscellaneous Provisions

            Section 5.1. Notices. All notices, requests, consents and demands
and other communications required under this Agreement, or pursuant to any other
instrument or document delivered hereunder shall be in writing and, unless
otherwise specifically provided, may be delivered personally, by telegram or
telex, or by registered or certified mail, postage prepaid, return receipt
requested, at the addresses specified on the signature page hereof (unless
changed by the particular party whose address is stated herein by similar notice
in writing), in which case the notice will be deemed delivered when received.

            Section 5.2. Amendments. No modification or amendment of or
supplement to this Agreement shall be valid or effective unless the same is in
writing and signed by all parties hereto, and neither the Depositor, the Master
Servicer nor the Trustee shall enter into any amendment hereof except as
permitted by the Pooling and Servicing Agreement. The Trustee shall give prompt
written notice to the Custodian of any amendment or supplement to the Pooling
and Servicing Agreement and furnish the Custodian with written copies thereof.

            Section 5.3. Governing Law. This Agreement shall be deemed a
contract made under the laws of the State of New York and shall be construed and
enforced in accordance with and governed by the laws of the State of New York.

            Section 5.4. Recordation of Agreement. To the extent permitted by
applicable law, this Agreement is subject to recordation in all appropriate
public offices for real property records in all the counties or other comparable
jurisdictions in which any or all of the properties subject to the Mortgages are
situated, and in any other appropriate public recording office or elsewhere,
such recordation to be effected by the Master Servicer and at its expense on
direction by the Trustee, but only upon direction accompanied by an Opinion of
Counsel to the effect that such recordation materially and beneficially affects
the interests of the Certificateholders.

            For the purpose of facilitating the recordation of this Agreement as
herein provided and for other purposes, this Agreement may be executed
simultaneously in any number of counterparts, each of which counterparts shall
be deemed to be an original, and such counterparts shall constitute but one and
the same instrument.

            Section 5.5. Severability of Provisions. If any one or more of the
covenants, agreements, provisions or terms of this Agreement shall be for any
reason whatsoever held invalid, then such covenants, agreements, provisions or
terms shall be deemed severable from the remaining covenants, agreements,
provisions or terms of this Agreement and shall in no way affect the validity or
enforceability of the other provisions of this Agreement or of the Certificates
or the rights of the holders thereof.

            Section 5.6. Regulation AB Compliance; Intent of Parties;
Reasonableness. The parties hereto acknowledge that interpretations of the
requirements of Regulation AB may change over time, whether due to interpretive
guidance provided by the Commission or its staff, consensus among participants
in the asset-backed securities markets, advice of counsel, or otherwise, and
agree to comply with requests made by the Depositor or the Master Servicer in
good faith for delivery of information under these provisions on the basis of
evolving interpretations of Regulation AB. In connection with the Trust, the
parties hereto shall cooperate fully with the Master Servicer and the Depositor
to deliver to the Master Servicer and/or the Depositor (including its assignees
or designees), any and all statements, reports, certifications, records and any
other information available to such party and reasonably necessary in the good
faith determination of the Depositor or the Master Servicer to permit the
Depositor or the Master Servicer to comply with the provisions of Regulation AB,
together with such disclosures reasonably believed by the Depositor or the
Master Servicer to be necessary in order to effect such compliance.

<PAGE>

            IN WITNESS WHEREOF, this Agreement is executed as of the date first
above written.


Address:                              HSBC BANK USA, NATIONAL ASSOCIATION,
                                         as Trustee


452 Fifth Avenue
New York, New York 10018              By:__________________________________
                                      Name:  Fernando Acebedo
                                      Title: Vice President


Address:                              WELLS FARGO ASSET SECURITIES CORPORATION,
                                         as Depositor


7430 New Technology Way
Frederick, Maryland 21703             By:__________________________________
                                      Name:  Bradley A. Davis
                                      Title: Vice President


Address:                              WELLS FARGO BANK, N.A.,
                                         as Master Servicer


9062 Old Annapolis Road
Columbia, Maryland 21045              By:__________________________________
                                      Name:  Carla S. Walker
                                      Title: Vice President


Address:                              WELLS FARGO BANK, N.A.,
                                         as Custodian


1015 10th Avenue South East
Minneapolis, Minnesota 55414          By:_________________________________
                                         Name:  Mary B. Hogan
                                         Title: Vice President

<PAGE>

STATE OF MARYLAND       )
                        ss.:
COUNTY OF FREDERICK     )


            On this 28th day of March, 2007, before me, a notary public in and
for the State of Maryland, personally appeared Bradley A. Davis, known to me
who, being by me duly sworn, did depose and say that he resides at Cooksville,
Maryland; that he is a Vice President of Wells Fargo Asset Securities
Corporation, a Delaware corporation, one of the parties that executed the
foregoing instrument; and that he signed his name thereto by order of the Board
of Directors of said corporation.



-------------------------
Notary Public

[NOTARIAL SEAL]

<PAGE>

STATE OF MARYLAND       )
                        ss.:
COUNTY OF HOWARD        )


            On this 28th day of March, 2007, before me, the undersigned officer,
personally appeared Carla S. Walker, and acknowledged to me to be the Vice
President of Wells Fargo Bank, National Association, and that as such officer,
being duly authorized to do so pursuant to such entity's by-laws or a resolution
of its board of directors, executed and acknowledged the foregoing instrument
for the purposes therein contained, by signing the name of such entity by
herself as such officer as her free and voluntary act and deed and the free and
voluntary act and deed and the free and voluntary act and deed of said entity.



            IN WITNESS WHEREOF, I hereunto set my hand and official seal.




-------------------------
Notary Public

[NOTARIAL SEAL]

<PAGE>

STATE OF NEW YORK             )
                              ss.:
COUNTY OF NEW YORK            )


            On this 28th day of March, 2007, before me, a notary public in and
for the State of New York, personally appeared Fernando Acebedo, known to me
who, being by me duly sworn, did depose and say that he resides in Huntington,
New York; that he is a Vice President of HSBC Bank USA, National Association, a
national banking association, one of the parties that executed the foregoing
instrument; and that he signed his name thereto by order of the Board of
Directors of said association.



-------------------------
Notary Public

[NOTARIAL SEAL]

<PAGE>

STATE OF MINNESOTA       )
                         ss.:
COUNTY OF   HENNEPIN     )


            On this 28th day of March, 2007, before me, a notary public in and
for the State of Minnesota, personally appeared Mary B. Hogan, known to me who,
being by me duly sworn, did depose and say that she is a Vice President of Wells
Fargo Bank, N.A., a national banking association, one of the parties that
executed the foregoing instrument; and that she signed her name thereto by order
of the Board of Directors of said association.



-------------------------
Notary Public

[NOTARIAL SEAL]


<PAGE>

                                    EXHIBIT F

                 Addresses for Requesting Mortgage Loan Schedule


In the case of the Depositor:

Wells Fargo Asset Securities Corporation
7430 New Technology Way
Frederick, Maryland 21703
Attention: Vice President - Structured Finance


In the case of the Master Servicer:

Wells Fargo Bank, N.A.
9062 Old Annapolis Road
Columbia, Maryland 21045-1951
Attention: Corporate Trust Services - WFMBS 2007-4

<PAGE>

                                    EXHIBIT G

                        REQUEST FOR RELEASE OF DOCUMENTS

To:   Wells Fargo Bank, N.A.
      1015 10th Avenue S.E.
      Minneapolis., MN  55414
      Attn: ________________

      Re:   Custodial Agreement, dated as of March 28, 2007, among HSBC Bank
            USA, National Association, as Trustee, Wells Fargo Asset Securities
            Corporation, as Depositor, Wells Fargo Bank, N.A., as Master
            Servicer, and Wells Fargo Bank, N.A., as Custodian, relating to the
            Wells Fargo Asset Securities Corporation; Mortgage Pass-Through
            Certificates, Series 2007-4.

            In connection with the administration of the Mortgage Loans held by
you as Custodian for the Trust Estate pursuant to the above-captioned Custodial
Agreement, we request the release, and hereby acknowledge receipt, of the
Custodian's Owner Mortgage Loan File for the Mortgage Loan described below, for
the reason indicated.

                              Mortgage Loan Number:

                       Mortgagor Name, Address & Zip Code:



            Reason for Requesting Documents (check one):

            _______           1.    Mortgage Paid in Full

            _______           2.    Foreclosure

            _______           3.    Substitution

            _______           4.    Other Liquidation (Repurchases, etc.)

            _______           5.    Nonliquidation

            Reason:____________________________________

            By:_______________________________________
                 (authorized signer)

            Issuer:_____________________________________


            Address:___________________________________

            ___________________________________________


            Date:_______________________________________

                                    Custodian

Wells Fargo Bank, N.A.

            Please acknowledge the execution of the above request by your
signature and date below:

------------------------------------            -----------------
Signature                                       Date



Documents returned to Custodian:

------------------------------------            -----------------
Custodian                                       Date

<PAGE>

                                    EXHIBIT H

                                            AFFIDAVIT PURSUANT TO SECTION
                                            860E(e)(4) OF THE INTERNAL REVENUE
                                            CODE OF 1986, AS AMENDED, AND FOR
                                            NON-ERISA INVESTORS



STATE OF                )
                        )  ss.:
COUNTY OF               )

             [NAME OF OFFICER], being first duly sworn, deposes and says:

            1. That he is [Title of Officer] of [Name of Purchaser] (the
"Purchaser"), a [description of type of entity] duly organized and existing
under the laws of the [State of ______] [United States], on behalf of which he
makes this affidavit.

            2. That the Purchaser's Taxpayer Identification Number is [       ].

            3. That the Purchaser is not a "disqualified organization" within
the meaning of Section 860E(e)(5),of the Internal Revenue Code of 1986, as
amended (the "Code"), or an ERISA Prohibited Holder, and will not be a
"disqualified organization" or an ERISA Prohibited Holder, as of [date of
transfer], and that the Purchaser is not acquiring Wells Fargo Asset Securities
Corporation Mortgage Pass-Through Certificates, Series 2007-4, Class A-R
Certificate (the "Residual Certificate") for the account of, or as agent
(including a broker, nominee, or other middleman) for, any person or entity from
which it has not received an affidavit substantially in the form of this
affidavit. For these purposes, a "disqualified organization" means the United
States, any state or political subdivision thereof, any foreign government, any
international organization, any agency or instrumentality of any of the
foregoing (other than an instrumentality if all of its activities are subject to
tax and a majority of its board of directors is not selected by such
governmental entity), any cooperative organization furnishing electric energy or
providing telephone service to persons in rural areas as described in Code
Section 1381(a)(2)(C), or any organization (other than a farmers' cooperative
described in Code Section 521) that is exempt from taxation under the Code
unless such organization is subject to the tax on unrelated business income
imposed by Code Section 511. For these purposes, an "ERISA Prohibited Holder"
means an employee benefit plan or other retirement arrangement subject to Title
I of the Employee Retirement Income Security Act of 1974, as amended ("ERISA"),
or Code Section 4975 or a governmental plan, as defined in Section 3(32) of
ERISA, subject to any federal, state or local law which is, to a material
extent, similar to the foregoing provisions of ERISA or the Code (collectively,
a "Plan") or a Person acting on behalf of or investing the assets of such a
Plan.

            4. That the Purchaser historically has paid its debts as they have
come due and intends to pay its debts as they come due in the future and the
Purchaser intends to pay taxes associated with holding the Residual Certificate
as they become due.

            5. That the Purchaser understands that it may incur tax liabilities
with respect to the Residual Certificate in excess of cash flows generated by
the Residual Certificate.

            6. That the Purchaser will not transfer the Residual Certificate to
any person or entity from which the Purchaser has not received an affidavit
substantially in the form of this affidavit and as to which the Purchaser has
actual knowledge that the requirements set forth in paragraph 3, 4 or 10 hereof
are not satisfied or that the Purchaser has reason to know does not satisfy the
requirements set forth in paragraph 4 hereof.

            7. That the Purchaser is aware that the Residual Certificate may be
a "noneconomic residual interest" within the meaning of Treasury regulations
promulgated pursuant to the Code and that the transferor of a noneconomic
residual interest will remain liable for any taxes due with respect to the
income on such residual interest, unless no significant purpose of the transfer
was to impede the assessment or collection of tax.

            8. That the Purchaser will not cause income from the Residual
Certificate to be attributable to a foreign permanent establishment or fixed
base, within the meaning of an applicable income tax treaty, of the Purchaser or
any other person.

            9. That, if the Purchaser is purchasing the Residual Certificate in
a transfer intended to meet the safe harbor provisions of Treasury Regulations
Sections 1.860E-1(c), the Purchaser has executed and attached Attachment A
hereto.

            10. That the Purchaser (i) is a U.S. Person or (ii) is a person
other than a U.S. Person (a "Non-U.S. Person") that holds the Residual
Certificate in connection with the conduct of a trade or business within the
United States and has furnished the transferor and the Trustee with an effective
Internal Revenue Service Form W-8ECI or successor form at the time and in the
manner required by the Code or (iii) is a Non-U.S. Person that has delivered to
both the transferor and the Trustee an opinion of a nationally recognized tax
counsel to the effect that the transfer of the Residual Certificate to it is in
accordance with the requirements of the Code and the regulations promulgated
thereunder and that such transfer of the Residual Certificate will not be
disregarded for federal income tax purposes. "U.S. Person" means a citizen or
resident of the United States, a corporation or partnership (unless, in the case
of a partnership, Treasury regulations are adopted that provide otherwise)
created or organized in or under the laws of the United States, any state
thereof or the District of Columbia, including an entity treated as a
corporation or partnership for federal income tax purposes, an estate whose
income is subject to United States federal income tax regardless of its source,
or a trust if a court within the United States is able to exercise primary
supervision over the administration of such trust, and one or more such U.S.
Persons have the authority to control all substantial decisions of such trust
(or, to the extent provided in applicable Treasury regulations, certain trusts
in existence on August 20, 1996 which are eligible to elect to be treated as
U.S. Persons).

            11. That the Purchaser agrees to such amendments of the Pooling and
Servicing Agreement as may be required to further effectuate the restrictions on
transfer of the Residual Certificate to such a "disqualified organization," an
agent thereof, an ERISA Prohibited Holder or a person that does not satisfy the
requirements of paragraph 4, paragraph 5 and paragraph 10 hereof.

            12. That the Purchaser consents to the designation of the Master
Servicer as its agent to act as "tax matters person" of each REMIC pursuant to
Section 8.13 of the Pooling and Servicing Agreement, and if such designation is
not permitted by the Code and applicable law, to act as tax matters person if
requested to do so.

<PAGE>

            IN WITNESS WHEREOF, the Purchaser has caused this instrument to be
executed on its behalf, pursuant to authority of its Board of Directors, by its
[Title of Officer] this ___ day of __________, 20__.


                                        [NAME OF PURCHASER]


                                       By:____________________________________
                                          [Name of Officer]
                                          [Title of Officer]

            Personally appeared before me the above-named [Name of Officer],
known or proved to me to be the same person who executed the foregoing
instrument and to be the [Title of Officer], of the Purchaser, and acknowledged
to me that he [she] executed the same as his [her] free act and deed and the
free act and deed of the Purchaser.

            Subscribed and sworn before me this __ day of __________, 20__.



Notary Public

COUNTY OF____________________

STATE OF_____________________

My commission expires the __ day of __________, 20__.

<PAGE>

                                  ATTACHMENT A

                                       to

 AFFIDAVIT PURSUANT TO SECTION 860E(e)(4) OF THE INTERNAL REVENUE CODE OF 1986,
                     AS AMENDED, AND FOR NON-ERISA INVESTORS



Check the appropriate box:

[_]   The consideration paid to the Purchaser to acquire the Residual
      Certificate equals or exceeds the excess of (a) the present value of the
      anticipated tax liabilities over (b) the present value of the anticipated
      savings associated with holding such Certificate, in each case calculated
      in accordance with U.S. Treasury Regulations Sections 1.860E-1(c)(7) and
      (8), computing present values using a discount rate equal to the
      short-term Federal rate prescribed by Section 1274(d) of the Code and the
      compounding period used by the Purchaser.

                                       OR

[_]   The transfer of the Residual Certificate complies with U.S. Treasury
      Regulations Sections 1.860E-1(c)(5) and (6) and, accordingly:

      (i)   the Purchaser is an "eligible corporation," as defined in U.S.
            Treasury Regulations Section 1.860E-1(c)(6)(i), as to which income
            from Residual Certificate will only be taxed in the United States;

      (ii)  at the time of the transfer, and at the close of the Purchaser's two
            fiscal years preceding the year of the transfer, the Purchaser had
            gross assets for financial reporting purposes (excluding any
            obligation of a person related to the Purchaser within the meaning
            of U.S. Treasury Regulations Section 1.860E-1(c)(6)(ii)) in excess
            of $100 million and net assets in excess of $10 million;

      (iii) the Purchaser will transfer the Residual Certificate only to another
            "eligible corporation," as defined in U.S. Treasury Regulations
            Section 1.860E-1(c)(6)(i), in a transaction that satisfies the
            requirements of Sections 1.860E-1(c)(4)(i), (ii) and (iii) and
            Section 1.860E-1(c)(5) of the U.S. Treasury Regulations;

      (iv)  the Purchaser has determined the consideration paid to it to acquire
            the Residual Certificate based on reasonable market assumptions
            (including, but not limited to, borrowing and investment rates,
            prepayment and loss assumptions, expense and reinvestment
            assumptions, tax rates and other factors specific to the Purchaser)
            that it has determined in good faith; and

      (v)   in the event of any transfer of the Residual Certificate by the
            Purchaser, the Purchaser will require its transferee to complete a
            representation in the form of this Attachment A as a condition of
            the transferee's purchase of the Residual Certificate.

<PAGE>

                                    EXHIBIT I

                 Letter from Transferor of Residual Certificate

                                     [Date]

Wells Fargo Bank, N.A.
9062 Old Annapolis Road
Columbia, Maryland 21045-1951
Attn: Corporate Trust Services- WFMBS 2007-4

Re:   Wells Fargo Asset Securities Corporation,
            Series 2007-4, Class A-R

Ladies and Gentlemen:

            [Transferor] has reviewed the attached affidavit of [Transferee],
and has no actual knowledge that such affidavit is not true and has no reason to
know that the information contained in paragraph 4 thereof is not true.


                                       Very truly yours,


                                       [Transferor]


                                       ----------------------


<PAGE>

                                    EXHIBIT J


                    WELLS FARGO ASSET SECURITIES CORPORATION

                       MORTGAGE PASS-THROUGH CERTIFICATES
                                  SERIES 2007-4
                       CLASS [B-4][B-5][B-6] CERTIFICATES

                               TRANSFEREE'S LETTER

                                                      _________________ __, ____

Wells Fargo Bank, N.A.
9062 Old Annapolis Road
Columbia, Maryland 21045-1951
Attn: Corporate Trust Services- WFMBS 2007-4

Wells Fargo Asset Securities Corporation
7430 New Technology Way
Frederick, Maryland 21703

            The undersigned (the "Purchaser") proposes to purchase Wells Fargo
Asset Securities Corporation Mortgage Pass-Through Certificates, Series 2007-4,
Class [B-4][B-5][B-6] Certificates (the "Class [B-4][B-5][B-6] Certificates") in
the principal amount of $___________. In doing so, the Purchaser hereby
acknowledges and agrees as follows:

            Section 1. Definitions. Each capitalized term used herein and not
otherwise defined herein shall have the meaning ascribed to it in the Pooling
and Servicing Agreement, dated as of March 28, 2007 (the "Pooling and Servicing
Agreement") among Wells Fargo Asset Securities Corporation, as depositor (the
"Depositor"), Wells Fargo Bank, N.A., as master servicer (the "Master Servicer")
and HSBC Bank USA, National Association, as trustee (the "Trustee"), of Wells
Fargo Asset Securities Corporation Mortgage Pass-Through Certificates, Series
2007-4.

            Section 2. Representations and Warranties of the Purchaser. In
connection with the proposed transfer, the Purchaser represents and warrants to
the Depositor, the Master Servicer and the Trustee that:

            (a) The Purchaser is duly organized, validly existing and in good
standing under the laws of the jurisdiction in which the Purchaser is organized,
is authorized to invest in the Class [B-4][B-5][B-6] Certificates, and to enter
into this Agreement, and duly executed and delivered this Agreement.

            (b) The Purchaser is acquiring the Class [B-4][B-5][B-6]
Certificates for its own account as principal and not with a view to the
distribution thereof, in whole or in part.

            (c) The Purchaser is a "Qualified Institutional Buyer" within the
meaning of Rule 144A of the Act.

            (d) The Purchaser confirms that (a) it has received and reviewed a
copy of the Private Placement Memorandum dated __________ __, 20__, relating to
the Class [B-4][B-5][B-6] Certificates and reviewed, to the extent it deemed
appropriate, the documents attached thereto or incorporated by reference
therein, (b) it has had the opportunity to ask questions of, and receive answers
from the Depositor concerning the Class [B-4][B-5][B-6] Certificates and all
matters relating thereto, and obtain any additional information (including
documents) relevant to its decision to purchase the Class [B-4][B-5][B-6]
Certificates that the Depositor possesses or can possess without unreasonable
effort or expense and (c) it has undertaken its own independent analysis of the
investment in the Class [B-4][B-5][B-6] Certificates. The Purchaser will not use
or disclose any information it receives in connection with its purchase of the
Class [B-4][B-5][B-6] Certificates other than in connection with a subsequent
sale of Class [B-4][B-5][B-6] Certificates.

            (e) Either (i) the Purchaser is not an employee benefit plan or
other retirement arrangement subject to Title I of the Employee Retirement
Income Security Act of 1974, as amended, ("ERISA"), or Section 4975 of the
Internal Revenue Code of 1986, as amended (the "Code"), or a governmental plan,
as defined in Section 3(32) of ERISA subject to any federal, state or local law
("Similar Law") which is, to a material extent, similar to the foregoing
provisions of ERISA or the Code (collectively, a "Plan"), an agent acting on
behalf of a Plan, or a person utilizing the assets of a Plan or (ii) if the
Purchaser is an insurance company, (A) the source of funds used to purchase the
Class [B-4][B-5][B-6] Certificate is an "insurance company general account" (as
such term is defined in Section V(e) of Prohibited Transaction Class Exemption
95-60 ("PTE 95-60"), 60 Fed. Reg. 35925 (July 12, 1995), (B) there is no Plan
with respect to which the amount of such general account's reserves and
liabilities for the contract(s) held by or on behalf of such Plan and all other
Plans maintained by the same employer (or affiliate thereof as defined in
Section V(a)(1) of PTE 95-60) or by the same employee organization exceeds 10%
of the total of all reserves and liabilities of such general account (as such
amounts are determined under Section I(a) of PTE 95-60) at the date of
acquisition and (C) the purchase and holding of such Class [B-4][B-5][B-6]
Certificates are covered by Sections I and III of PTE 95-60 or (iii) the
Purchaser has provided (a) a "Benefit Plan Opinion" satisfactory to the
Depositor and the Master Servicer of the Trust Estate and (b) such other
opinions of counsel, officers' certificates and agreements as the Depositor or
the Master Servicer may have required. A Benefit Plan Opinion is an opinion of
counsel to the effect that the proposed transfer will not constitute or result
in a non-exempt prohibited transaction within the meaning of ERISA, Section 4975
of the Code or Similar Law and will not subject the Depositor or the Master
Servicer to any obligation in addition to those undertaken in the Pooling and
Servicing Agreement (including any liability for civil penalties or excise taxes
imposed pursuant to ERISA, Section 4975 of the Code or Similar Law).

            (f) If the Purchaser is a depository institution subject to the
jurisdiction of the Office of the Comptroller of the Currency ("OCC"), the Board
of Governors of the Federal Reserve System ("FRB"), the Federal Deposit
Insurance Corporation ("FDIC"), the Office of Thrift Supervision ("OTS") or the
National Credit Union Administration ("NCUA"), the Purchaser has reviewed the
"Supervisory Policy Statement on Securities Activities" dated January 28, 1992
of the Federal Financial Institutions Examination Council and the April 15, 1994
Interim Revision thereto as adopted by the OCC, FRB, FDIC, OTS and NCUA (with
modifications as applicable), as appropriate, other applicable investment
authority, rules, supervisory policies and guidelines of these agencies and, to
the extent appropriate, state banking authorities and has concluded that its
purchase of the Class [B-4][B-5][B-6] Certificates is in compliance therewith.

            Section 3. Transfer of Class [B-4][B-5][B-6] Certificates.

            (a) The Purchaser understands that the Class [B-4][B-5][B-6]
Certificates have not been registered under the Securities Act of 1933 (the
"Act") or any state securities laws and that no transfer may be made unless the
Class [B-4][B-5][B-6] Certificates are registered under the Act and applicable
state law or unless an exemption from registration is available. The Purchaser
further understands that neither the Depositor nor the Master Servicer is under
any obligation to register the Class [B-4][B-5][B-6] Certificates or make an
exemption available. Any such Certificateholder desiring to effect such transfer
shall, and does hereby agree to, indemnify the Trustee, the Master Servicer, any
Paying Agent and the Depositor against any liability that may result if the
transfer is not so exempt or is not made in accordance with such federal and
state laws.

            (b) No transfer of a Class [B-4][B-5][B-6] Certificate shall be made
unless the transferee provides the Depositor and the Master Servicer with a
Transferee's Letter, substantially in the form of this Agreement.

            (c) The Purchaser acknowledges that its Class [B-4][B-5][B-6]
Certificates bear a legend setting forth the applicable restrictions on
transfer.

<PAGE>

            IN WITNESS WHEREOF, the undersigned has caused this Agreement to be
validly executed by its duly authorized representative as of the day and the
year first above written.


                                       [PURCHASER]


                                       By: ______________________________


                                       Its: ______________________________


<PAGE>

                                    EXHIBIT K

                           LIST OF RECORDATION STATES

                                     Florida

                                    Maryland


<PAGE>

                                    EXHIBIT L

                              SERVICING AGREEMENTS

                      Wells Fargo Bank Servicing Agreement

      [Included as Exhibit 10.1 to the Current Report on Form 8-K pursuant
            to which this Pooling and Servicing Agreement is filed.]


<PAGE>

                                    EXHIBIT M

                      [FORM OF SPECIAL SERVICING AGREEMENT]

                 SPECIAL SERVICING AND COLLATERAL FUND AGREEMENT


      This SPECIAL SERVICING AND COLLATERAL FUND AGREEMENT (the "Agreement") is
made and entered into as of [_____], between Wells Fargo Bank, N.A. (the
"Company" or the "Master Servicer") and [_____] (the "Purchaser").

                              PRELIMINARY STATEMENT

      The Purchaser is the holder of the entire interest in Wells Fargo Asset
Securities Corporation Mortgage Pass-Through Certificates, Series [_____], Class
[_____] (the "Class B Certificates"), which are the Lowest Priority Certificates
(as defined below) outstanding with respect to such Series. The Class B
Certificates were issued pursuant to a Pooling and Servicing Agreement dated as
of [_____] among Wells Fargo Asset Securities Corporation, as depositor (the
"Depositor"), Wells Fargo Bank, N.A., as Master Servicer and HSBC Bank USA,
National Association, as Trustee.

      In connection with the ownership by the Purchaser of the Lowest Priority
Certificates, the Purchaser and the Company have agreed that (i) the Purchaser,
for so long as it owns 100% of the Lowest Priority Certificates, will have the
unilateral right to control foreclosure decisions with respect to delinquent
mortgage loans and (ii) the Company will provide to the Purchaser certain
information with respect to the Mortgage Loans;

      The parties hereto have agreed that the Company will cause, to the extent
that the Company as Master Servicer is granted such authority in the related
Servicing Agreements, the related servicers (each a related "Servicer"), which
service the Mortgage Loans which comprise the Trust Estate related to the above
referenced series under the related servicing agreements (each a related
"Servicing Agreement"), to engage in certain special servicing procedures
relating to foreclosures for the benefit of the Purchaser, and that the
Purchaser will deposit funds in a collateral fund to cover any losses
attributable to such procedures as well as all advances and costs in connection
therewith, as set forth herein.

      In consideration of the mutual agreements herein contained, the receipt
and sufficiency of which are hereby acknowledged, the Company and the Purchaser
agree that the following provisions shall become effective and shall be binding
on and enforceable by the Company and the Purchaser:

<PAGE>

                                    ARTICLE I

                                   DEFINITIONS

Section 1.02. Defined Terms.

      Whenever used in this Agreement, the following words and phrases, unless
the context otherwise requires, shall have the following meanings:

      Business Day: Any day other than (i) a Saturday or a Sunday or (ii) a day
on which banking institutions in the State of New York are required or
authorized by law or executive order to be closed.

      Collateral Fund: The fund established and maintained pursuant to Section
3.01 hereof.

      Collateral Fund Permitted Investments: Either (i) obligations of, or
obligations fully guaranteed as to principal and interest by, the United States,
or any agency or instrumentality thereof, provided such obligations are backed
by the full faith and credit of the United States, (ii) a money market fund
rated in the highest rating category by a nationally recognized rating agency
selected by the Company, (iii) cash, (iv) mortgage pass-through certificates
issued or guaranteed by Government National Mortgage Association, FNMA or FHLMC,
(v) commercial paper (including both non-interest-bearing discount obligations
and interest-bearing obligations payable on demand or on a specified date), the
issuer of which may be an affiliate of the Company, having at the time of such
investment a rating of at least F-1 by Fitch Ratings ("Fitch"), at least P-1 by
Moody's Investors Service, Inc. ("Moody's") or at least A-1 by Standard &
Poor's, a division of The McGraw Hill Companies, Inc. ("S&P") or (vi) demand and
time deposits in, certificates of deposit of, any depository institution or
trust company (which may be an affiliate of the Company) incorporated under the
laws of the United States of America or any state thereof and subject to
supervision and examination by federal and/or state banking authorities, so long
as at the time of such investment either (x) the long-term debt obligations of
such depository institution or trust company have a rating of at least AA by
Fitch, Aa2 by Moody's or AA by S&P, (y) the certificate of deposit or other
unsecured short-term debt obligations of such depository institution or trust
company have a rating of at least F-1 by Fitch, P-1 by Moody's or A-1 by S&P or
(z) the depository institution or trust company is one that is acceptable to
either Fitch, Moody's or S&P and, for each of the preceding clauses (i), (iv),
(v) and (vi), the maturity thereof shall be not later than the earlier to occur
of (A) 30 days from the date of the related investment and (B) the next
succeeding Distribution Date as defined in the related Pooling and Servicing
Agreement.

      Commencement of Foreclosure: The first official action required under
local law in order to commence foreclosure proceedings or to schedule a
trustee's sale under a deed of trust, including (i) in the case of a mortgage,
any filing or service of process necessary to commence an action to foreclose,
or (ii) in the case of a deed of trust, posting, the publishing, filing or
delivery of a notice of sale, but not including in either case (x) any notice of
default, notice of intent to foreclose or sell or any other action prerequisite
to the actions specified in (i) or (ii) above, (y) the acceptance of a
deed-in-lieu of foreclosure (whether in connection with a sale of the related
property or otherwise) or (z) initiation and completion of a short pay-off.

      Current Appraisal: With respect to any Mortgage Loan as to which the
Purchaser has made an Election to Delay Foreclosure, an appraisal of the related
Mortgaged Property obtained by the Purchaser at its own expense from an
independent appraiser (which shall not be an affiliate of the Purchaser)
acceptable to the Company as nearly contemporaneously as practicable to the time
of the Purchaser's election, prepared based on the Company's customary
requirements for such appraisals.

      Election to Delay Foreclosure: Any election by the Purchaser to delay the

      Commencement of Foreclosure, made in accordance with Section 2.02(b).

      Election to Foreclose: Any election by the Purchaser to proceed with the
Commencement of Foreclosure, made in accordance with Section 2.03(a).

      Lowest Priority Certificates: The most subordinate class of certificates
issued under the Pooling and Servicing Agreement that is outstanding from time
to time. If the Lowest Priority Certificates are reduced to zero as a result of
losses or otherwise, and if the Purchaser at that time owns 100% of the most
subordinate class of certificates issued under the Pooling and Servicing
Agreement then remaining outstanding, then such most subordinate class remaining
outstanding shall thereafter be deemed to be the Lowest Priority Certificates
for all purposes of this Agreement.

      Monthly Advances: Principal and interest advances and servicing advances
including costs and expenses of foreclosure.

      Required Collateral Fund Balance: As of any date of determination, an
amount equal to the aggregate of all amounts previously required to be deposited
in the Collateral Fund pursuant to Section 2.02(d) (after adjustment for all
withdrawals and deposits pursuant to Section 2.02(e)) and Section 2.03(b) (after
adjustment for all withdrawals and deposits pursuant to Section 2.03(c)) and
Section 3.02 to be reduced by all withdrawals therefrom pursuant to Section
2.02(g) and Section 2.03(d).

      Section 1.03. Definitions Incorporated by Reference.

      All capitalized terms not otherwise defined in this Agreement shall have
the meanings assigned in the Pooling and Servicing Agreement.

<PAGE>

                                   ARTICLE II

                          SPECIAL SERVICING PROCEDURES

            Section 2.01. Reports and Notices.

            (a) In connection with the performance of its duties under the
Pooling and Servicing Agreement relating to the realization upon defaulted
Mortgage Loans, the Company as Master Servicer shall provide to the Purchaser
the following notices and reports:

      Within five Business Days after each Distribution Date (or included in or
      with the monthly statements to Certificateholders pursuant to the Pooling
      and Servicing Agreement), the Company shall provide to the Purchaser a
      report identifying all loans delinquent 30 days or more (including all
      loans in foreclosure, bankruptcy or "real estate owned" status) (each, a
      "Delinquency Report"). The Delinquency Report shall use the same
      methodology and calculations employed in the Company's standard servicing
      reports, indicating the number of Mortgage Loans that are (i) thirty days
      delinquent, (ii) sixty days delinquent, (iii) ninety days or more
      delinquent, (iv) in foreclosure, (v) in bankruptcy or (vi) real estate
      owned, and indicating for each such Mortgage Loan the loan number, the
      property address and the outstanding principal balance.

            (b) If requested by the Purchaser, the Company shall cause the
Servicer (to the extent that the Company as Master Servicer is granted such
authority in the related Servicing Agreement) to make its servicing personnel
available (during their normal business hours) to respond to reasonable
inquiries, by phone or in writing by facsimile, electronic, or overnight mail
transmission, by the Purchaser in connection with any Mortgage Loan (i)
identified in a report under Section 2.01 (a) (ii), (a) (iii), (a) (iv), (a) (v)
or (a) (vi); provided, that (1) the related Servicer shall only be required to
provide information that is readily accessible to its servicing personnel and
(2) the related Servicer shall respond within five Business Days orally or in
writing by facsimile transmission.

            (c) In addition to the foregoing, the Company shall cause the
Servicer (to the extent that the Company as Master Servicer is granted such
authority in the related Servicing Agreement) to provide to the Company (for
prompt transmission to the Purchaser) such information as the Purchaser may
reasonably request provided, however, that such information is consistent with
normal reporting practices, concerning each Mortgage Loan that is at least
ninety days delinquent and each Mortgage Loan which has become real estate
owned, through the final liquidation thereof; provided, that the related
Servicer shall only be required to provide information that is readily
accessible to its servicing personnel; provided, however, that the Purchaser
will reimburse the Company and the related Servicer for any out of pocket
expenses.

            Section 2.02. Purchaser's Election to Delay Foreclosure Proceedings.

            (a) The Purchaser shall be deemed to direct the Company to direct
(to the extent that the Company as Master Servicer is granted such authority in
the related Servicing Agreement) the related Servicer that in the event that the
Company does not receive written notice of the Purchaser's election pursuant to
subsection (b) below within 48 hours (exclusive of any intervening non-Business
Days) of transmission of the Delinquency Report provided by the Company under
Section 2.01 (a) (subject to extension as set forth in Section 2.02(b), the
related Servicer may proceed with the Commencement of Foreclosure in respect of
each Mortgage Loan reported under Section 2.01 (a)(ii) or 2.01 (a)(iii) in
accordance with its normal foreclosure policies without further notice to the
Purchaser. Any foreclosure that has been initiated may be discontinued (i)
without notice to the Purchaser if the Mortgage Loan has been brought current or
if a refinancing or prepayment occurs with respect to the Mortgage Loan
(including by means of a short payoff approved by the related Servicer) or (ii)
if the related Servicer has reached the terms of a forbearance agreement with
the borrower.

            (b) In connection with any Mortgage Loan reported in a Delinquency
Report under Section 2.01(a)(ii) or 2.01 (a)(iii), the Purchaser may elect to
instruct the Company to cause, to the extent that the Company as Master Servicer
is granted such authority in the related Servicing Agreement, the related
Servicer to delay the Commencement of Foreclosure until such time as the
Purchaser determines that the related Servicer may proceed with the Commencement
of Foreclosure. Such election must be evidenced by written notice received
within 48 hours (exclusive of any intervening non-Business Days) of transmission
of the Delinquency Report provided by the Company under Section 2.01(a). Such 48
hour period shall be extended for no longer than an additional four Business
Days after the receipt of the information if the Purchaser requests additional
information related to such foreclosure; provided, however, that the Purchaser
will have at least one Business Day to respond to any requested additional
information. Any such additional information shall be provided only to the
extent it is obtainable by the related Servicer from existing reports,
certificates or statements or is otherwise readily accessible to its servicing
personnel. The Purchaser agrees that it has no right to deal with the mortgagor
during such period. However, if such servicing activities include acceptance of
a deed-in-lieu of foreclosure or short payoff, the Purchaser will be notified
and given two Business Days to respond.

            (c) With respect to any Mortgage Loan as to which the Purchaser has
made an Election to Delay Foreclosure, the Purchaser shall obtain a Current
Appraisal as soon as practicable, but in no event more than 15 Business Days
thereafter, and shall provide the Company with a copy of such Current Appraisal.

            (d) Within two Business Days of making any Election to Delay
Foreclosure, the Purchaser shall remit by wire transfer to the Company, for
deposit in the Collateral Fund, an amount, as calculated by the Company, equal
to the sum of (i) 125% of the greater of the unpaid principal balance of the
Mortgage Loan and the value shown in the Current Appraisal referred to in
subsection (c) above (or, if such Current Appraisal has not yet been obtained,
the Company's estimate thereof, in which case the required deposit under this
subsection shall be adjusted upon obtaining such Current Appraisal), and (ii)
three months' interest on the Mortgage Loan at the applicable Mortgage Interest
Rate. If any Election to Delay Foreclosure extends for a period in excess of
three months (such excess period being referred to herein as the "Excess
Period"), within two Business Days the Purchaser shall remit by wire transfer in
advance to the Company for deposit in the Collateral Fund the amount of each
additional month's interest, as calculated by the Company, equal to interest on
the Mortgage Loan at the applicable Mortgage Interest Rate for the Excess
Period. The terms of this Agreement will no longer apply to the servicing of any
Mortgage Loan upon the failure of the Purchaser to deposit any of the above
amounts relating to the Mortgage Loan within two Business Days of the Election
to Delay Foreclosure or within two Business Days of the commencement of the
Excess Period subject to Section 3.01.

            (e) With respect to any Mortgage Loan as to which the Purchaser has
made an Election to Delay Foreclosure, the Company may withdraw from the
Collateral Fund from time to time amounts necessary to reimburse the related
Servicer for all related Monthly Advances and Liquidation Expenses thereafter
made by such Servicer in accordance with the Pooling and Servicing Agreement and
the related Servicing Agreement. To the extent that the amount of any such
Liquidation Expenses is determined by the Company based on estimated costs, and
the actual costs are subsequently determined to be higher, the Company may
withdraw the additional amount from the Collateral Fund. In the event that the
Mortgage Loan is brought current by the mortgagor and the foreclosure action is
discontinued, the amounts so withdrawn from the Collateral Fund shall be
redeposited if and to the extent that reimbursement therefor from amounts paid
by the mortgagor is not prohibited pursuant to the Pooling and Servicing
Agreement or the related Servicing Agreement, applicable law or the related
mortgage note. Except as provided in the preceding sentence, amounts withdrawn
from the Collateral Fund to cover Monthly Advances and Liquidation Expenses
shall not be redeposited therein or otherwise reimbursed to the Purchaser. If
and when any such Mortgage Loan is brought current by the mortgagor, all amounts
remaining in the Collateral Fund in respect of such Mortgage Loan (after
adjustment for all permitted withdrawals and deposits pursuant to this
subsection) shall be released to the Purchaser.

            (f) With respect to any Mortgage Loan as to which the Purchaser has
made an Election to Delay Foreclosure, the related Servicer shall continue to
service the Mortgage Loan in accordance with its customary procedures (other
than the delay in Commencement of Foreclosure as provided herein). If and when
the Purchaser shall notify the Company that it believes that it is appropriate
to do so, the related Servicer may proceed with the Commencement of Foreclosure.
In any event, if the Mortgage Loan is not brought current by the mortgagor by
the time the loan becomes 6 months delinquent, the Purchaser's election shall no
longer be effective and at the Purchaser's option, either (i) the Purchaser
shall purchase the Mortgage Loan from the related Trust Estate at a purchase
price equal to the sum of (x) accrued and unpaid interest on the Mortgage Loan
at the applicable Mortgage Interest Rate through the last day of the month of
repurchase, (y) 100% of the unpaid principal balance of the Mortgage Loan as of
such purchase date and (z) any additional amount needed to reimburse any
unreimbursed related Periodic Advance or other servicing advances made in
respect of such Mortgage Loan, to be paid by (A) applying any balance in the
Collateral Fund to such purchase price, and (B) to the extent of any deficiency,
by wire transfer of immediately available funds from the Purchaser to the
Company for deposit in the related Certificate Account; or (ii) the related
Servicer shall proceed with the Commencement of Foreclosure. In the event that
the Purchaser purchases any such Mortgage Loan, the Servicer shall continue to
service the Mortgage Loan for the Purchaser pursuant to the applicable Servicing
Agreement.

            (g) Upon the occurrence of a liquidation with respect to any
Mortgage Loan as to which the Purchaser made an Election to Delay Foreclosure
and as to which the related Servicer proceeded with the Commencement of
Foreclosure in accordance with subsection (f) above, the Company shall calculate
the amount, if any, by which the value shown on the Current Appraisal obtained
under subsection (c) exceeds the actual sales price obtained for the related
Mortgaged Property (net of Liquidation Expenses and accrued interest related to
the extended foreclosure period), and the Company shall withdraw the amount of
such excess from the Collateral Fund, shall remit the same to the Trust Estate
and in its capacity as Master Servicer shall apply such amount as additional
Liquidation Proceeds pursuant to the Pooling and Servicing Agreement. After
making such withdrawal, all amounts remaining in the Collateral Fund in respect
of such Mortgage Loan (after adjustment for all permitted withdrawals and
deposits pursuant to this Agreement) shall be released to the Purchaser.

            Section 2.03. Purchaser's Election to Commence Foreclosure
Proceedings.

            (a) In connection with any Mortgage Loan identified in a Delinquency
Report under Section 2.01(a)(ii), the Purchaser, for so long as the Purchaser
owns 100% of the Lowest Priority Certificates, may elect to instruct the Company
to cause, to the extent that the Company as Master Servicer is granted such
authority in the related Servicing Agreement, the related Servicer to proceed
with the Commencement of Foreclosure as soon as practicable. Such election must
be evidenced by written notice received by the Company by 5:00 p.m., New York
City time, on the third Business Day following the delivery of such Delinquency
Report.

            (b) Within two Business Days of making any Election to Foreclose,
the Purchaser shall remit to the Company, for deposit in the Collateral Fund, an
amount, as calculated by the Company, equal to 125% of the current unpaid
principal balance of the Mortgage Loan and three months interest on the Mortgage
Loan at the applicable Mortgage Interest Rate. If and when any such Mortgage
Loan is brought current by the mortgagor, all amounts in the Collateral Fund in
respect of such Mortgage Loan (after adjustment for all permitted withdrawals
and deposits pursuant to this Agreement) shall be released to the Purchaser if
and to the extent that reimbursement therefor from amounts paid by the mortgagor
is not prohibited pursuant to the Pooling and Servicing Agreement or the related
Servicing Agreement, applicable law or the related mortgage note. The terms of
this Agreement will no longer apply to the servicing of any Mortgage Loan upon
the failure of the Purchaser to deposit the above amounts relating to the
Mortgage Loan within two Business Days of the Election to Foreclose subject to
Section 3.01.

            (c) With respect to any Mortgage Loan as to which the Purchaser has
made an Election to Foreclose, the related Servicer shall continue to service
the Mortgage Loan in accordance with its customary procedures (other than
Commencement of Foreclosure as provided herein). In connection therewith, the
Company shall have the same rights to make withdrawals for Monthly Advances and
Liquidations Expenses from the Collateral Fund as are provided under Section
2.02(e), and the Company shall make reimbursements thereto to the limited extent
provided under such subsection in accordance with its customary procedures. The
Company shall not be required to cause, to the extent that the Company as Master
Servicer is granted such authority in the related Servicing Agreement, the
related Servicer to proceed with the Commencement of Foreclosure if (i) the same
is stayed as a result of the mortgagor's bankruptcy or is otherwise barred by
applicable law, or to the extent that all legal conditions precedent thereto
have not yet been complied with, or (ii) the Company believes there is a breach
of representations or warranties by the Company, a Servicer, or the Depositor,
which may result in a repurchase or substitution of such Mortgage Loan, or (iii)
the Company or related Servicer reasonably believes the Mortgaged Property may
be contaminated with or affected by hazardous wastes or hazardous substances
(and, without limiting the related Servicer's right not to proceed with the
Commencement of Foreclosure, the Company supplies the Purchaser with information
supporting such belief). Any foreclosure that has been initiated may be
discontinued (x) without notice to the Purchaser if the Mortgage Loan has been
brought current or if a refinancing or prepayment occurs with respect to the
Mortgage Loan (including by means of a short payoff) or (y) if the related
Servicer has reached the terms of a forbearance agreement.

            (d) Upon the occurrence of a liquidation with respect to any
Mortgage Loan as to which the Purchaser made an Election to Foreclose and as to
which the related Servicer proceeded with the Commencement of Foreclosure in
accordance with subsection (c) above, the Company shall calculate the amount, if
any, by which the unpaid principal balance of the Mortgage Loan at the time of
liquidation (plus all unreimbursed interest and servicing advances and
Liquidation Expenses in connection therewith other than those paid from the
Collateral Fund) exceeds the actual sales price obtained for the related
Mortgaged Property, and the Company shall withdraw the amount of such excess
from the Collateral Fund, shall remit the same to the Trust Estate and in its
capacity as Master Servicer shall apply such amount as additional Liquidation
Proceeds pursuant to the Pooling and Servicing Agreement. After making such
withdrawal, all amounts remaining in the Collateral Fund (after adjustment for
all withdrawals and deposits pursuant to subsection (c) in respect of such
Mortgage Loan shall be released to the Purchaser.

            Section 2.04. Termination.

            (a) With respect to all Mortgage Loans included in the Trust Estate,
the Purchaser's right to make any Election to Delay Foreclosure or any Election
to Foreclose and the Company's obligations under Section 2.01 shall terminate
(i) at such time as the Principal Balance of the Class B Certificates has been
reduced to zero, (ii) if the greater of (x) 43% (or such lower or higher
percentage that represents the related Servicer's actual historical loss
experience with respect to the Mortgage Loans in the related pool as determined
by the Company) of the aggregate principal balance of all Mortgage Loans that
are in foreclosure or are more than 90 days delinquent on a contractual basis
and REO properties or (y) the aggregate amount that the Company estimates
through the normal servicing practices of the related Servicer will be required
to be withdrawn from the Collateral Fund with respect to Mortgage Loans as to
which the Purchaser has made an Election to Delay Foreclosure or an Election to
Foreclosure, exceeds (z) the then-current principal balance of the Class B
Certificates, (iii) upon any transfer by the Purchaser of any interest (other
than the minority interest therein, but only if the transferee provides written
acknowledgment to the Company of the Purchaser's right hereunder and that such
transferee will have no rights hereunder) in the Class B Certificates (whether
or not such transfer is registered under the Pooling and Servicing Agreement),
including any such transfer in connection with a termination of the Trust Estate
or (iv) upon any breach of the terms of this Agreement by the Purchaser.

            (b) Except as set forth in 2.04(a), this Agreement and the
respective rights, obligations and responsibilities of the Purchaser and the
Company hereunder shall terminate upon the later to occur of (i) the final
liquidation of the last Mortgage Loan as to which the Purchaser made any
Election to Delay Foreclosure or any Election to Foreclose and the withdrawal of
all remaining amounts in the Collateral Fund as provided herein and (ii) ten
Business Days' notice. The Purchaser's right to make an election pursuant to
Section 2.02 or Section 2.03 hereof with respect to a particular Mortgage Loan
shall terminate if the Purchaser fails to make any deposit required pursuant to
Section 2.02(d) or 2.03(b) or if the Purchaser fails to make any other deposit
to the Collateral Fund pursuant to this Agreement.

                                  ARTICLE III

                       COLLATERAL FUND; SECURITY INTEREST

            Section 3.01. Collateral Fund.

      Upon receipt from the Purchaser of the initial amount required to be
deposited in the Collateral Fund pursuant to Article II, the Company shall
establish and maintain with [ ] as a segregated account on its books and records
an account (the "Collateral Fund"), entitled "Wells Fargo Bank, N.A., as Master
Servicer, for the benefit of registered holders of Wells Fargo Asset Securities
Corporation Mortgage Pass-Through Certificates, Series [ ]." Amounts held in the
Collateral Fund shall continue to be the property of the Purchaser, subject to
the first priority security interest granted hereunder for the benefit of the
Certificateholders, until withdrawn from the Collateral Fund pursuant to Section
2.02 or 2.03 hereof. The Collateral Fund shall be an "outside reserve fund"
within the meaning of the REMIC Provisions, beneficially owned by the Purchaser
for federal income tax purposes. All income, gain, deduction or loss with
respect to the Collateral Fund shall be that of the Purchaser. All distributions
from the Trust Fund to the Collateral Fund shall be treated as distributed to
the Purchaser as the beneficial owner thereof.

      Upon the termination of this Agreement and the liquidation of all Mortgage
Loans as to which the Purchaser has made any Election to Delay Foreclosure or
any Election to Foreclose pursuant to Section 2.04 hereof, the Company shall
distribute or cause to be distributed to the Purchaser all amounts remaining in
the Collateral Fund (after adjustment for all deposits and permitted withdrawals
pursuant to this Agreement) together with any investment earnings thereon. In
the event the Purchaser has made any Election to Delay Foreclosure or any
Election to Foreclose, prior to any distribution to the Purchaser of all amounts
remaining in the Collateral Fund, funds in the Collateral Fund shall be applied
consistent with the terms of this Agreement.

            Section 3.02. Collateral Fund Permitted Investments.

      The Company shall, at the written direction of the Purchaser, invest the
funds in the Collateral Fund in Collateral Fund Permitted Investments. Such
direction shall not be changed more frequently than quarterly. In the absence of
any direction, the Company shall select such investments in accordance with the
definition of Collateral Fund Permitted Investments in its discretion. All
income and gain realized from any investment as well as any interest earned on
deposits in the Collateral Fund (net of any losses on such investments) and any
payments of principal made in respect of any Collateral Fund Permitted
Investment shall be deposited in the Collateral Fund upon receipt. All costs and
realized losses associated with the purchase and sale of Collateral Fund
Permitted Investments shall be borne by the Purchaser and the amount of net
realized losses shall be deposited by the Purchaser in the Collateral Fund
promptly upon realization. The Company shall periodically (but not more
frequently than monthly) distribute to the Purchaser upon request an amount of
cash, to the extent cash is available therefore in the Collateral Fund, equal to
the amount by which the balance of the Collateral Fund, after giving effect to
all other distributions to be made from the Collateral Fund on such date,
exceeds the Required Collateral Fund Balance. Any amounts so distributed shall
be released from the lien and security interest of this Agreement.

            Section 3.03. Grant of Security Interest.

      The Purchaser hereby grants to the Company for the benefit of the
Certificateholders under the Pooling and Servicing Agreement a security interest
in and lien on all of the Purchaser's right, title and interest, whether now
owned or hereafter acquired, in and to: (1) the Collateral Fund, (2) all amounts
deposited in the Collateral Fund and Collateral Fund Permitted Investments in
which such amounts are invested (and the distributions and proceeds of such
investments) and (3) all cash and non-cash proceeds of any of the foregoing,
including proceeds of the voluntary conversion thereof (all of the foregoing
collectively, the "Collateral").

      The Purchaser acknowledges the lien on and the security interest in the
Collateral for the benefit of the Certificateholders. The Purchaser shall take
all actions requested by the Company as may be reasonably necessary to perfect
the security interest created under this Agreement in the Collateral and cause
it to be prior to all other security interests and liens, including the
execution and delivery to the Company for filing of appropriate financing
statements in accordance with applicable law. The Company shall file appropriate
continuation statements, or appoint an agent on its behalf to file such
statements, in accordance with applicable law.

            Section 3.04. Collateral Shortfalls.

      In the event that amounts on deposit in the Collateral Fund at any time
are insufficient to cover any withdrawals therefrom that the Company is then
entitled to make hereunder, the Purchaser shall be obligated to pay such amounts
to the Company immediately upon demand. Such obligation shall constitute a
general corporate obligation of the Purchaser. The failure to pay such amounts
within two Business Days of such demand (except for amounts to cover interest on
a Mortgage Loan pursuant to Sections 2.02(d) and 2.03 (b)), shall cause an
immediate termination of the Purchaser's right to make any Election to Delay
Foreclosure or Election to Foreclose and the Company's obligations under this
Agreement with respect to all Mortgage Loans to which such insufficiencies
relate, without the necessity of any further notice or demand on the part of the
Company.

                                   ARTICLE IV

            Section 4.01. Assessment of Servicing Compliance; Registered Public
Accounting Firm Attestation Reports; Exchange Act Reporting.

            (a) The Purchaser shall furnish, or cause to be furnished in the
case of clause (iii), to the Master Servicer, no later than March 5 of each year
or if such day is not a Business Day, the next Business Day (with a 10 calendar
day cure period, but in no event later than March 15), commencing in March 20 ,
the following:

            (i) a report (in form and substance reasonably satisfactory to the
      Master Servicer and the Depositor) regarding the Purchaser's assessment of
      compliance with the Servicing Criteria applicable to it during the
      immediately preceding calendar year, as required under Rules 13a-18 and
      15d-18 of the Exchange Act and Item 1122 of Regulation AB. Such report
      shall be addressed to the Master Servicer and signed by an authorized
      officer of the Purchaser, and shall address, at a minimum, each of the
      Servicing Criteria applicable to the Purchaser;

            (ii) a report of a registered public accounting firm reasonably
      acceptable to the Master Servicer and the Depositor that attests to, and
      reports on, the assessment of compliance made by the Purchaser and
      delivered pursuant to the preceding paragraph. Such attestation shall be
      in accordance with Rules 1-02(a)(3) and 2-02(g) of Regulation S-X under
      the Securities Act and the Exchange Act. If requested by the Master
      Servicer or the Depositor, such report shall contain or be accompanied by
      a consent of such accounting firm to inclusion or incorporation of such
      report in the Depositor's Registration Statement on Form S-3 relating to
      the Certificates and the Trust's Form 10-K; and

            (iii) an assessment of compliance and accountants' attestation as
      described in paragraphs (i) and (ii) of this Section 4.01(a) with respect
      to each Subcontractor determined by the Purchaser pursuant to Section 4.02
      to be "participating in the servicing function" within the meaning of Item
      1122 of Regulation AB.

            An assessment of compliance provided by a Subcontractor pursuant to
Section 4.01(a)(iii) need not address any elements of the Servicing Criteria
applicable to it other than those specified by the Purchaser pursuant to Section
4.02.

            No later than 30 days following the end of each fiscal year for the
Trust for which a Form 10-K is required to be filed, the Purchaser shall forward
to the Master Servicer the name of each Subcontractor engaged by it and what
Servicing Criteria will be addressed in the report on assessment of compliance
prepared by such Subcontractor. When the Purchaser submits its assessment to the
Master Servicer, it will also at such time include the assessment (and
attestation pursuant to Section 4.01(a)(ii) hereof) of each Subcontractor
engaged by it.

            (b) Within five (5) calendar days after a Distribution Date, the
Purchaser shall provide to the Master Servicer, to the extent known, in
EDGAR-compatible format, or in such other form as otherwise agreed upon by the
Master Servicer and the Purchaser, the form and substance of any Additional Form
10-D Disclosure applicable to the Purchaser, as indicated in the table in
Exhibit S to the Pooling and Servicing Agreement. The Purchaser acknowledges
that the performance by the Master Servicer of its duties under Section 3.12(a)
of the Pooling and Servicing Agreement relating to the timely preparation and
filing of Form 10-D is contingent upon the Purchaser strictly observing all
applicable deadlines in the performance of its duties under this Section
4.01(b).

            (c) No later than March 5 (with a 10 calendar day cure period, but
in no event later than March 15) of each year that the Trust is subject to the
Exchange Act reporting requirements, commencing in March 20 , the Purchaser
shall provide to the Master Servicer, to the extent known, in EDGAR-compatible
format, or in such other form as otherwise agreed upon by the Master Servicer
and the Purchaser, the form and substance of any Additional Form 10-K Disclosure
applicable to the Purchaser, as indicated in the table in Exhibit T to the
Pooling and Servicing Agreement. The Purchaser acknowledges that the performance
by the Master Servicer of its duties under Section 3.12(b) of the Pooling and
Servicing Agreement relating to the timely preparation and filing of Form 10-K
is contingent upon the Purchaser strictly observing all applicable deadlines in
the performance of its duties under this Section 4.01(c).

            t 12 0 (d) For so long as the Trust is subject to the Exchange Act
reporting requirements, no later than the end of business on the second Business
Day after the occurrence of a Reportable Event applicable to the Purchaser, the
Purchaser shall provide to the Master Servicer, to the extent known, in
EDGAR-compatible format, or in such other form as otherwise agreed upon by the
Master Servicer and the Purchaser, the form and substance of any Form 8-K
Disclosure Information applicable to the Purchaser, as indicated in the table in
Exhibit U to the Pooling and Servicing Agreement. The Purchaser acknowledges
that the performance by the Master Servicer of its duties under Section 3.12(c)
of the Pooling and Servicing Agreement relating to the timely preparation and
filing of Form 8-K is contingent upon the Purchaser strictly observing all
applicable deadlines in the performance of its duties under this Section
4.01(d).

            (e) The Purchaser shall provide such information regarding itself as
the Master Servicer or the Depositor request for the purpose of complying with
Item 1108 of Regulation AB, including at a minimum, the information set forth in
Exhibit A.

            (f) The Purchaser shall indemnify the Master Servicer, each
affiliate of the Master Servicer, the Trust, each broker dealer acting as
underwriter or initial purchaser of the Certificates, each Person who controls
any of such parties and the Depositor (within the meaning of Section 15 of the
Securities Act and Section 20 of the Exchange Act); and the respective present
and former directors, officers, employees and agents of each of the foregoing
and of the Depositor (each such entity, an "Indemnified Party"), and shall hold
each of them harmless from and against any losses, damages, penalties, fines,
forfeitures, legal fees and expenses and related costs, judgments, and any other
costs, fees and expenses that any of them may sustain arising out of or based
upon:

                  (i) (A) any untrue statement of a material fact contained or
            alleged to be contained in any information, report, certification,
            accountants' letter or other material provided in written or
            electronic form under this Section 4.01 or Section 4.02 hereof by or
            on behalf of the Purchaser, or provided under Sections 4.01 or 4.02
            by or on behalf of any Subcontractor (collectively, the "Purchaser
            Information"), or (B) the omission or alleged omission to state in
            the Purchaser Information a material fact required to be stated in
            the Purchaser Information or necessary in order to make the
            statements therein, in the light of the circumstances under which
            they were made, not misleading; provided, by way of clarification,
            that clause (B) of this paragraph shall be construed solely by
            reference to the Purchaser Information and not to any other
            information communicated in connection with a sale or purchase of
            securities, without regard to whether the Purchaser Information or
            any portion thereof is presented together with or separately from
            such other information; or

                  (ii) any failure by the Purchaser or any Subcontractor engaged
            by the Purchaser to deliver any information, report, certification,
            accountants' letter or other material when and as required under
            Sections 4.01 or 4.02, including any failure by the Purchaser to
            identify pursuant to Section 4.02 any Subcontractor "participating
            in the servicing function" within the meaning of Item 1122 of
            Regulation AB.

      In the case of any failure of performance described in clause (ii) of this
Section, the Purchaser shall promptly reimburse the Master Servicer and the
Depositor, as applicable, for all costs reasonably incurred by each such party
in order to obtain the information, report, certification, accountants' letter
or other material not delivered as required by the Purchaser or any
Subcontractor. If the indemnification provided for herein is unavailable to hold
harmless any Indemnified Party, then the Purchaser agrees that it shall
contribute to the amount paid or payable by such Indemnified Party as a result
of the losses, claims, damages or liabilities of such Indemnified Party in such
proportion as is appropriate to reflect the relative fault of such Indemnified
Party on the one hand and the Purchaser on the other in connection with a breach
of the Purchaser's obligations under this Section 4.1 or the Purchaser's
negligence, bad faith or willful misconduct in connection therewith.

            (g) Notwithstanding anything contained in this Section 4.01 to the
contrary, the provisions of this Section 4.01 shall not apply to the Purchaser
with respect to any calendar year unless the Purchaser exercises its rights set
forth under Sections 2.02 or 2.03 of this Agreement in such calendar year.

            Section 4.02. Engagement of Affiliates or Third-Parties.

            The Purchaser shall not hire any Subservicer without the consent of
the Master Servicer and the Depositor. The Purchaser shall not hire or otherwise
utilize the services of any Subcontractor to fulfill any of the obligations of
the Purchaser as servicer under this Agreement unless the Purchaser complies
with the provisions of this Section.

            It shall not be necessary for the Purchaser to seek the consent of
the Master Servicer or the Depositor to the utilization of any Subcontractor.
The Purchaser shall promptly upon request provide to the Master Servicer (or any
designee of Master Servicer) a written description (in form and substance
satisfactory to the Master Servicer and the Depositor) of the role and function
of each Subcontractor utilized by the Purchaser, specifying (i) the identity of
each such Subcontractor, (ii) which (if any) of such Subcontractors are
"participating in the servicing function" within the meaning of Item 1122 of
Regulation AB, and (iii) which elements of the Servicing Criteria will be
addressed in assessments of compliance provided by each Subcontractor identified
pursuant to clause (ii) of this paragraph.

            As a condition to the utilization of any Subcontractor determined to
be "participating in the servicing function" within the meaning of Item 1122 of
Regulation AB, the Purchaser shall cause any such Subcontractor used by the
Purchaser, for the benefit of the Master Servicer and the Depositor to comply
with the provisions of Section 4.01 of this Agreement to the same extent as if
such Subcontractor were the Purchaser. The Purchaser shall be responsible for
obtaining from each Subcontractor and delivering to the Master Servicer any
assessment of compliance and attestation required to be delivered by such
Subcontractor under Section 4.01, in each case as and when required to be
delivered.

            Section 4.03. Notification of Merger.

            The Purchaser and such successor or surviving Person shall notify
the Depositor, the Master Servicer and the Trustee of any such merger,
conversion or consolidation at least two Business Days prior to the effective
date thereof and shall provide the Depositor and the Master Servicer with all
information required by the Depositor to comply with its reporting obligations
not later than the effective date of such merger, conversion or consolidation
(unless giving prior notice would be prohibited by applicable law or by a
confidentiality agreement, in which case notice shall be given by 12 noon
eastern time one Business Day after such merger or consolidation).

            Section 4.04. Compliance with Article IV.

            If (a) the Purchaser fails to comply with its obligations to deliver
any assessment of servicing compliance or registered public accounting firm
attestation reports required pursuant to this Article IV or (b) any
Subcontractor engaged by the Purchaser fails to comply with its obligations to
deliver any assessment of servicing compliance or registered public accounting
firm attestation reports, the Master Servicer, may, after consultation with the
Depositor, terminate this Agreement pursuant to Section 2.04(a)(iv).

                                   ARTICLE V

                            MISCELLANEOUS PROVISIONS

            Section 5.01. Amendment.

      This Agreement may be amended from time to time by the Company and the
Purchaser by written agreement signed by the Company and the Purchaser, subject
to the acknowledgement of the Rating Agencies as contemplated in Section 3.08 of
the Pooling and Servicing Agreement with respect to such amendment.

            Section 5.02. Counterparts.

      This Agreement may be executed simultaneously in any number of
counterparts, each of which counterparts shall be deemed to be an original, and
such counterparts shall constitute but one and the same instrument.

            Section 5.03. Governing Law.

      This Agreement shall be construed in accordance with the laws of the State
of New York and the obligations, rights and remedies of the parties hereunder
shall be determined in accordance with such laws.

            Section 5.04. Notices.

      All demands, notices and direction hereunder shall be in writing or by
telecopy and shall be deemed effective upon receipt to:

      (a) in the case of the Company,
            Wells Fargo Bank, N.A.
            9062 Old Annapolis Road
            Columbia, MD 21045

            Attention: Vice President, Master Servicing
            Phone: 410-884-2000
            Fax: 410-715-1573

      (b) in the case of the Purchaser,


            Section 5.05. Severability of Provisions.

      If any one or more of the covenants, agreements, provisions or terms of
this Agreement shall be for any reason whatsoever, including regulatory, held
invalid, then such covenants, agreements, provisions or terms of this Agreement
and shall in no way affect the validity or enforceability of the other
provisions of this Agreement.

            Section 5.06. Successors and Assigns.

      The provisions of this Agreement shall be binding upon and inure to the
benefit of the respective successors and assigns of the parties hereto, and all
such provisions shall inure to the benefit of the Certificateholders; provided,
however, that the rights under this Agreement cannot be assigned by the
Purchaser without the consent of the Company.

            Section 5.07. Article and Section Headings.

      The article and section headings herein are for convenience of reference
only and shall not limit or otherwise affect the meaning hereof.

            Section 5.08. Confidentiality.

      The Purchaser agrees that all information supplied by or on behalf of the
Company pursuant to Sections 2.01 or 2.02, including individual account
information, is the property of the Company and the Purchaser agrees to hold
such information confidential and not to disclose such information.

      Each party hereto agrees that neither it, nor any officer, director,
employee, affiliate or independent contractor acting at such party's direction
will disclose the terms of Section 5.09 of this Agreement to any person or
entity other than such party's legal counsel except pursuant to a final,
non-appealable order of court, the pendency of such order the other party will
have received notice of at least five business days prior to the date thereof,
or pursuant to the other party's prior express written consent.

            Section 5.09. Indemnification.

      The Purchaser agrees to indemnify and hold harmless the Company, the
Depositor, and each Servicer and each person who controls the Company, the
Depositor, or a Servicer and each of their respective officers, directors,
affiliates and agents acting at the Company's, the Depositor's, or a Servicer's
direction (the "Indemnified Parties") against any and all losses, claims,
damages or liabilities to which they may be subject, insofar as such losses,
claims, damages or liabilities (or actions in respect thereof) arise out of, or
are based upon, actions taken by, or actions not taken by, the Company, the
Depositor, or a Servicer, or on their behalf, in accordance with the provisions
of this Agreement and (i) which actions conflict with the Company's, the
Depositor's, or a Servicer's obligations under the Pooling and Servicing
Agreement or the related Servicing Agreement, or (ii) give rise to securities
law liability under federal or state securities laws with respect to the
Certificates. The Purchaser hereby agrees to reimburse the Indemnified Parties
for the reasonable legal or other expenses incurred by them in connection with
investigating or defending any such loss, claim, damage, liability or action.
The indemnification obligations of the Purchaser hereunder shall survive the
termination or expiration of this Agreement.

            Section 5.10 Regulation AB Compliance; Intent of Parties;
Reasonableness.

            The parties hereto acknowledge that interpretations of the
requirements of Regulation AB may change over time, whether due to interpretive
guidance provided by the Commission or its staff, consensus among participants
in the asset-backed securities markets, advice of counsel, or otherwise, and
agree to comply with requests made by the Depositor or the Master Servicer in
good faith for delivery of information under these provisions on the basis of
evolving interpretations of Regulation AB. In connection with the Trust, the
parties hereto shall cooperate fully with the Master Servicer and the Depositor
to deliver to the Master Servicer and/or the Depositor (including its assignees
or designees), any and all statements, reports, certifications, records and any
other information available to such party and reasonably necessary in the good
faith determination of the Depositor or the Master Servicer to permit the
Depositor or the Master Servicer to comply with the provisions of Regulation AB,
together with such disclosures reasonably believed by the Depositor or the
Master Servicer to be necessary in order to effect such compliance.

<PAGE>

      IN WITNESS WHEREOF, the Company and the Purchaser have caused their names
to be signed hereto by their respective officers thereunto duly authorized, all
as of the day and year first above written.

                                    WELLS FARGO BANK, N.A.

                                    By:
                                       -----------------------------------------
                                       Name:
                                       Title:

                                    [NAME OF PURCHASER]

                                    By:
                                       -----------------------------------------
                                       Name:
                                       Title:

<PAGE>

                                                                       EXHIBIT A

                              PURCHASER INFORMATION

      (A) the Purchaser's form of organization;

      (B) a description of how long the Purchaser has been servicing residential
mortgage loans; a general discussion of the Purchaser's experience in servicing
assets of any type as well as a more detailed discussion of the Purchaser's
experience in, and procedures for, the servicing function it will perform under
the Agreement; information regarding the size, composition and growth of the
Purchaser's portfolio of residential mortgage loans of a type similar to the
Mortgage Loans and information on factors related to the Purchaser that may be
material, in the good faith judgment of the Master Servicer or the Depositor, to
any analysis of the servicing of the Mortgage Loans or the related asset-backed
securities, as applicable, including, without limitation:

            (1) whether any prior securitizations of mortgage loans of a type
      similar to the Mortgage Loans involving the Purchaser have defaulted or
      experienced an early amortization or other performance triggering event
      because of servicing during the three-year period immediately preceding
      the date of engagement of the Purchaser;

            (2) the extent of outsourcing the Purchaser utilizes;

            (3) whether there has been previous disclosure of material
      noncompliance with the applicable servicing criteria with respect to
      securitizations of residential mortgage loans involving the Purchaser as a
      servicer during the three-year period immediately preceding the date of
      engagement of the Purchaser;

            (4) whether the Purchaser has been terminated as servicer in a
      residential mortgage loan securitization, either due to a servicing
      default or to application of a servicing performance test or trigger; and

            (5) such other information as the Master Servicer or the Depositor
      may reasonably request for the purpose of compliance with Item 1108(b)(2)
      of Regulation AB;

      (C) a description of any material changes during the three-year period
immediately preceding the date of engagement of the Purchaser to the Purchaser's
policies or procedures with respect to the servicing function it will perform
under the Agreement for mortgage loans of a type similar to the Mortgage Loans;

      (D) information regarding the Purchaser's financial condition, to the
extent that there is a material risk that an adverse financial event or
circumstance involving the Purchaser could have a material adverse effect on the
performance by the Purchaser of its servicing obligations under the Agreement;

      (E) information regarding advances made by the Purchaser on the Mortgage
Loans and the Purchaser's overall servicing portfolio of residential mortgage
loans for the three-year period immediately preceding the date of engagement of
the Purchaser, which may be limited to a statement by an authorized officer of
the Purchaser to the effect that the Purchaser has made all advances required to
be made on residential mortgage loans serviced by it during such period, or, if
such statement would not be accurate, information regarding the percentage and
type of advances not made as required, and the reasons for such failure to
advance;

      (F) a description of the Purchaser's processes and procedures designed to
address any special or unique factors involved in servicing loans of a similar
type as the Mortgage Loans;

      (G) a description of the Purchaser's processes for handling delinquencies,
losses, bankruptcies and recoveries, such as through liquidation of mortgaged
properties, sale of defaulted mortgage loans or workouts; and

      (H) information as to how the Purchaser defines or determines
delinquencies and charge-offs, including the effect of any grace period,
re-aging, restructuring, partial payments considered current or other practices
with respect to delinquency and loss experience.

<PAGE>

                                    EXHIBIT N

                 FORM OF INITIAL CERTIFICATION OF THE CUSTODIAN

                                 March 28, 2007

Wells Fargo Asset Securities Corporation
7430 New Technology Way
Frederick, Maryland  21703

Wells Fargo Bank, N.A.
9062 Old Annapolis Road
Columbia, Maryland 21045-1951
Attn: Corporate Trust Services WFMBS 2007-4

HSBC Bank USA, National Association
452 Fifth Avenue
New York, New York 10018
Attention: Fernando Acebedo

      Re:   The Pooling and Servicing Agreement, dated March 28, 2007, among
            Wells Fargo Asset Securities Corporation, as Depositor, Wells Fargo
            Bank, N.A., as Master Servicer, and HSBC Bank USA, National
            Association, as Trustee, relating to the Wells Fargo Asset
            Securities Corporation; Mortgage Pass-Through Certificates, Series
            2007-4.

Ladies and Gentlemen:

      In accordance with the provisions of Section 2.02 of the above-referenced
Pooling and Servicing Agreement (the "Pooling and Servicing Agreement"), the
undersigned, as Custodian on behalf of the Trustee, hereby certifies that,
except as specified in any list of exceptions attached hereto, it has received
the original Mortgage Note relating to each of the Mortgage Loans listed on the
Mortgage Loan Schedule.

      The Custodian has made no independent examination of any documents
contained in each Mortgage File beyond the review specifically required in the
Pooling and Servicing Agreement in connection with this initial certification.
The Custodian makes no representations as to: (i) the validity, legality,
sufficiency, enforceability, recordability or genuineness of any of the
documents contained in each Mortgage File or any of the Mortgage Loans
identified in the Mortgage Loan Schedule or (ii) the collectibility,
insurability, effectiveness or suitability of any such Mortgage Loan.

      Capitalized terms used but not defined herein shall have the meanings
ascribed to such terms in the Pooling and Servicing Agreement.

                                    WELLS FARGO BANK, N.A.,
                                      as Custodian on behalf of the Trustee

                                       By:
                                          --------------------------------------
                                       Name:
                                            ------------------------------------
                                       Title:
                                             -----------------------------------
<PAGE>

                                    EXHIBIT O

                  FORM OF FINAL CERTIFICATION OF THE CUSTODIAN

                             [___________ __, ____]

Wells Fargo Asset Securities Corporation
7430 New Technology Way
Frederick, Maryland  21703

Wells Fargo Bank, N.A.
9062 Old Annapolis Road
Columbia, Maryland 21045-1951
Attn: Corporate Trust Services WFMBS 2007-4

HSBC Bank USA, National Association
452 Fifth Avenue
New York, New York 10018
Attention: Fernando Acebedo

      Re:   The Pooling and Servicing Agreement, dated March 28, 2007, among
            Wells Fargo Asset Securities Corporation, as Depositor, Wells Fargo
            Bank, N.A., as Master Servicer, and HSBC Bank USA, National
            Association, as Trustee, relating to the Wells Fargo Asset
            Securities Corporation; Mortgage Pass-Through Certificates, Series
            2007-4.

Ladies and Gentlemen:

      In accordance with the provisions of Section 2.02 of the above-referenced
Pooling and Servicing Agreement (the "Pooling and Servicing Agreement"), the
undersigned, as Custodian on behalf of the Trustee, hereby certifies that, as to
each Mortgage Loan listed in the Mortgage Loan Schedule, except as may be
specified in any list of exceptions attached hereto, such Mortgage File contains
all of the items required to be delivered pursuant to Section 2.01 of the
Pooling and Servicing Agreement.

      The Custodian has made no independent examination of any documents
contained in each Mortgage File beyond the review specifically required in the
Pooling and Servicing Agreement in connection with this final certification. The
Custodian makes no representations as to: (i) the validity, legality,
sufficiency, enforceability, recordability or genuineness of any of the
documents contained in each Mortgage File or any of the Mortgage Loans
identified in the Mortgage Loan Schedule or (ii) the collectibility,
insurability, effectiveness or suitability of any such Mortgage Loan.

      Capitalized terms used but not defined herein shall have the meanings
ascribed to such terms in the Pooling and Servicing Agreement.

                                    WELLS FARGO BANK, N.A.,
                                      as Custodian on behalf of the Trustee

                                       By:
                                          --------------------------------------
                                       Name:
                                            ------------------------------------
                                       Title:
                                             -----------------------------------

<PAGE>

                                    EXHIBIT P

                      FORM OF SARBANES-OXLEY CERTIFICATION

                    Wells Fargo Asset Securities Corporation
                       Mortgage Pass-Through Certificates,
                                  Series 2007-4

            I, [________], certify that:

      1. I have reviewed this report on Form 10-K and all reports on Form 10-D
required to be filed in respect of the period covered by this report on Form
10-K of the Wells Fargo Asset Securities Corporation, Mortgage Pass-Through
Certificates, Series 2007-4 Trust (the "Exchange Act Periodic Reports");

      2. Based on my knowledge, the Exchange Act Periodic Reports, taken as a
whole, do not contain any untrue statement of a material fact or omit to state a
material fact necessary to make the statements made, in light of the
circumstances under which such statements were made, not misleading with respect
to the period covered by this report;

      3. Based on my knowledge, all of the distribution, servicing and other
information required to be provided under Form 10-D for the period covered by
this report is included in the Exchange Act Periodic Reports;

      4. I am responsible for reviewing the activities performed by the Master
Servicer and based upon my knowledge and the compliance review conducted in
preparing the servicer compliance statement required in this report under Item
1123 of Regulation AB, and except as disclosed in the Exchange Act Periodic
Reports, the Master Servicer has fulfilled its obligations under the pooling and
servicing agreement, dated March 28, 2007, among Wells Fargo Asset Securities
Corporation, as depositor, Wells Fargo Bank, N.A., as master servicer, and HSBC
Bank USA, National Association, as trustee, in all material respects; and

      5. All of the reports on assessment of compliance with the servicing
criteria for asset-backed securities and their related attestation reports on
assessment of compliance with servicing criteria for asset-backed securities
required to be included in this report in accordance with Item 1122 of
Regulation AB and Exchange Act Rules 13a-18 and 15d-18 have been included as an
exhibit to this report, except as otherwise disclosed in this report. Any
material instances of noncompliance described in such reports have been
disclosed in this report on Form 10-K.

      [The following is included only for a transaction where there are
Servicers other than Wells Fargo Bank: In giving the certifications above, I
have reasonably relied on information provided to me by the following
unaffiliated parties: [Name of Servicers other than Wells Fargo Bank], as
Servicer.]


Date: [_____]

                                       By:
                                          --------------------------------------
                                          Name:
                                          Title:

<PAGE>

                                    EXHIBIT Q

                                   [Reserved]

<PAGE>

                                    EXHIBIT R

         Servicing Criteria to be Addressed in Assessment of Compliance

<TABLE>
<CAPTION>
                                            SERVICING CRITERIA                                   APPLICABLE SERVICING CRITERIA
------------------------------------------------------------------------------------------------------------------------------------
                                                                                            Master                            Custo-
     Reference                                     Criteria                                Servicer    Trustee   Servicers     dian
------------------------------------------------------------------------------------------------------------------------------------

                                       General Servicing Considerations

<S>                  <C>                                                                   <C>         <C>         <C>         <C>
1122(d)(1)(i)        Policies and procedures are instituted to monitor any performance         X        X(1)         X
                     or other triggers and events of default in accordance with the
                     transaction agreements.

1122(d)(1)(ii)       If any material servicing activities are outsourced to third              X                     X
                     parties, policies and procedures are instituted to monitor the
                     third party's performance and compliance with such servicing
                     activities.

1122(d)(1)(iii)      Any requirements in the transaction agreements to maintain a
                     back-up servicer for the mortgage loans are maintained.

1122(d)(1)(iv)       A fidelity bond and errors and omissions policy is in effect on the       X          X          X            X
                     party participating in the servicing function throughout the
                     reporting period in the amount of coverage required by and
                     otherwise in accordance with the terms of the transaction
                     agreements.

                                      Cash Collection and Administration

1122(d)(2)(i)        Payments on mortgage loans are deposited into the appropriate             X                     X
                     custodial bank accounts and related bank clearing accounts no more
                     than two business days following receipt, or such other number of
                     days specified in the transaction agreements.

1122(d)(2)(ii)       Disbursements made via wire transfer on behalf of an obligor or to        X                     X
                     an investor are made only by authorized personnel.

1122(d)(2)(iii)      Advances of funds or guarantees regarding collections, cash flows         X        X (2)        X
                     or distributions, and any interest or other fees charged for such
                     advances, are made, reviewed and approved as specified in the
                     transaction agreements.

1122(d)(2)(iv)       The related accounts for the transaction, such as cash reserve            X                     X
                     accounts or accounts established as a form of
                     overcollateralization, are separately maintained (e.g., with
                     respect to commingling of cash) as set forth in the transaction
                     agreements.

1122(d)(2)(v)        Each custodial account is maintained at a federally insured               X                     X
                     depository institution as set forth in the transaction agreements.
                     For purposes of this criterion, "federally insured depository
                     institution" with respect to a foreign financial institution means
                     a foreign financial institution that meets the requirements of Rule
                     13k-1(b)(1) of the Securities Exchange Act.

1122(d)(2)(vi)       Unissued checks are safeguarded so as to prevent unauthorized             X                     X
                     access.

1122(d)(2)(vii)      Reconciliations are prepared on a monthly basis for all                   X                     X
                     asset-backed securities related bank accounts, including custodial
                     accounts and related bank clearing accounts. These reconciliations
                     are (A) mathematically accurate; (B) prepared within 30 calendar
                     days after the bank statement cutoff date, or such other number of
                     days specified in the transaction agreements; (C) reviewed and
                     approved by someone other than the person who prepared the
                     reconciliation; and (D) contain explanations for reconciling items.
                     These reconciling items are resolved within 90 calendar days of
                     their original identification, or such other number of days
                     specified in the transaction agreements.

                                      Investor Remittances and Reporting

1122(d)(3)(i)        Reports to investors, including those to be filed with the                X                     X
                     Commission, are maintained in accordance with the transaction
                     agreements and applicable Commission requirements. Specifically,
                     such reports (A) are prepared in accordance with timeframes and
                     other terms set forth in the transaction agreements; (B) provide
                     information calculated in accordance with the terms specified in
                     the transaction agreements; (C) are filed with the Commission as
                     required by its rules and regulations; and (D) agree with
                     investors' or the trustee's records as to the total unpaid
                     principal balance and number of mortgage loans serviced by the
                     Servicer.

1122(d)(3)(ii)       Amounts due to investors are allocated and remitted in accordance         X                     X
                     with timeframes, distribution priority and other terms set forth in
                     the transaction agreements.

1122(d)(3)(iii)      Disbursements made to an investor are posted within two business          X                     X
                     days to the Servicer's investor records, or such other number of
                     days specified in the transaction agreements.

1122(d)(3)(iv)       Amounts remitted to investors per the investor reports agree with         X                     X
                     cancelled checks, or other form of payment, or custodial bank
                     statements.

                                          Pool Asset Administration

1122(d)(4)(i)        Collateral or security on mortgage loans is maintained as required        X                     X            X
                     by the transaction agreements or related mortgage loan documents.

1122(d)(4)(ii)       Mortgage loan and related documents are safeguarded as required by                              X            X
                     the transaction agreements

1122(d)(4)(iii)      Any additions, removals or substitutions to the asset pool are            X          X          X
                     made, reviewed and approved in accordance with any conditions or
                     requirements in the transaction agreements.

1122(d)(4)(iv)       Payments on mortgage loans, including any payoffs, made in                                      X
                     accordance with the related mortgage loan documents are posted to
                     the Servicer's obligor records maintained no more than two business
                     days after receipt, or such other number of days specified in the
                     transaction agreements, and allocated to principal, interest or
                     other items (e.g., escrow) in accordance with the related mortgage
                     loan documents.

1122(d)(4)(v)        The Servicer's records regarding the mortgage loans agree with the                              X
                     Servicer's records with respect to an obligor's unpaid principal
                     balance.

1122(d)(4)(vi)       Changes with respect to the terms or status of an obligor's               X                     X
                     mortgage loans (e.g., loan modifications or re-agings) are made,
                     reviewed and approved by authorized personnel in accordance with
                     the transaction agreements and related pool asset documents.

1122(d)(4)(vii)      Loss mitigation or recovery actions (e.g., forbearance plans,             X                     X
                     modifications and deeds in lieu of foreclosure, foreclosures and
                     repossessions, as applicable) are initiated, conducted and
                     concluded in accordance with the timeframes or other requirements
                     established by the transaction agreements.

1122(d)(4)(viii)     Records documenting collection efforts are maintained during the                                X
                     period a mortgage loan is delinquent in accordance with the
                     transaction agreements. Such records are maintained on at least a
                     monthly basis, or such other period specified in the transaction
                     agreements, and describe the entity's activities in monitoring
                     delinquent mortgage loans including, for example, phone calls,
                     letters and payment rescheduling plans in cases where delinquency
                     is deemed temporary (e.g., illness or unemployment).

1122(d)(4)(ix)       Adjustments to interest rates or rates of return for mortgage loans                             X
                     with variable rates are computed based on the related mortgage loan
                     documents.

1122(d)(4)(x)        Regarding any funds held in trust for an obligor (such as escrow                                X
                     accounts): (A) such funds are analyzed, in accordance with the
                     obligor's mortgage loan documents, on at least an annual basis, or
                     such other period specified in the transaction agreements; (B)
                     interest on such funds is paid, or credited, to obligors in
                     accordance with applicable mortgage loan documents and state laws;
                     and (C) such funds are returned to the obligor within 30 calendar
                     days of full repayment of the related mortgage loans, or such other
                     number of days specified in the transaction agreements.

1122(d)(4)(xi)       Payments made on behalf of an obligor (such as tax or insurance                                 X
                     payments) are made on or before the related penalty or expiration
                     dates, as indicated on the appropriate bills or notices for such
                     payments, provided that such support has been received by the
                     servicer at least 30 calendar days prior to these dates, or such
                     other number of days specified in the transaction agreements.

1122(d)(4)(xii)      Any late payment penalties in connection with any payment to be                                 X
                     made on behalf of an obligor are paid from the Servicer's funds and
                     not charged to the obligor, unless the late payment was due to the
                     obligor's error or omission.

1122(d)(4)(xiii)     Disbursements made on behalf of an obligor are posted within two                                X
                     business days to the obligor's records maintained by the Servicer,
                     or such other number of days specified in the transaction
                     agreements.

1122(d)(4)(xiv)      Delinquencies, charge-offs and uncollectible accounts are                 X                     X
                     recognized and recorded in accordance with the transaction
                     agreements.

1122(d)(4)(xv)       Any external enhancement or other support, identified in Item           X(3)
                     1114(a)(1) through (3) or Item 1115 of Regulation AB, is maintained
                     as set forth in the transaction agreements.
</TABLE>


[________________________]


Date: __________________________

By:_____________________________
   Name:
   Title:

(1)   This Servicing Criterion applies to the Trustee with respect to Events of
      Default as set forth in the Pooling and Servicing Agreement.

(2)   This Servicing Criterion applies to the Trustee if the Trustee was
      required during the preceding calendar year to make an Advance in
      accordance with Section 8.14 of the Pooling and Servicing Agreement.

(3)   This Servicing Criterion applies to the Master Servicer only for
      transactions that contain any external credit enhancement or other support
      identified in Item 1114(a)(1) through (3) or Item 1115 of Regulation AB.

<PAGE>

                                    EXHIBIT S

                         Additional Form 10-D Disclosure

Item on Form 10-D                           Party Responsible
--------------------------------------------------------------------------------

Item 1: Distribution and Pool               Master Servicer, Depositor
       Performance Information

      Any information required by 1121
      which is NOT included on the
      Distribution Date Statement

Item 2: Legal Proceedings per Item          (i) All parties to the Pooling
      1117 of Reg AB                        and Servicing Agreement, the
                                            Custodian, each Servicer and, if
                                            applicable the Special Servicer (as
                                            to themselves), (ii) the Master
                                            Servicer as to the issuing entity,
                                            (iii) the Depositor as to the
                                            sponsor, any 1110(b) originator, any
                                            1100(d)(1) party

Item 3: Sale of Securities and Use of       Depositor
       Proceeds

Item 4: Defaults Upon Senior Securities     Master Servicer

Item 5: Submission of Matters to a          Master Servicer, Trustee
       Vote of Security Holders

Item 6: Significant Obligors of Pool        Depositor, if applicable
       Assets

Item 7: Significant Enhancement             Depositor, if applicable
       Provider Information

Item 8: Other Information                   Any party responsible for
                                            disclosure items on Form 8-K

Item 9: Exhibits                            Depositor, Master Servicer

<PAGE>

                                    EXHIBIT T

                         Additional Form 10-K Disclosure
--------------------------------------------------------------------------------
Item on Form 10-K                            Party Responsible
--------------------------------------------------------------------------------

Item 1B: Unresolved Staff Comments           Depositor

Item 9B: Other Information                   Any party responsible for
                                             disclosure items on Form 8-K

Item 15: Exhibits, Financial Statement       Master Servicer
       Schedules                             Depositor

Additional Item:                             (i) All parties to the Pooling
                                             and Servicing Agreement, the
Disclosure per Item 1117 of Reg AB           Custodian, each Servicer and, if
                                             applicable the Special Servicer
                                             (as to themselves), (ii) the
                                             Master Servicer as to the
                                             issuing entity, (iii) the
                                             Depositor as to the sponsor, any
                                             1110(b) originator, any
                                             1100(d)(1) party

Additional Item:                             (i) All parties to the Pooling
Disclosure per Item 1119 of Reg AB           and Servicing Agreement, the
                                             Custodian, each Servicer and, if
                                             applicable the Special Servicer (as
                                             to themselves), (ii) the Master
                                             Servicer as to the issuing entity,
                                             (iii) the Depositor as to the
                                             sponsor, any 1110(b) originator,
                                             any 1100(d)(1) party, any
                                             significant obligor, any credit
                                             enhancement provider or derivative
                                             counterparty

Additional Item:                             Depositor, if applicable
Disclosure per Item 1112(b) of Reg AB

Additional Item:                             Depositor, if applicable
Disclosure per Items 1114(b) and
1115(b) of Reg AB

<PAGE>

                                    EXHIBIT U

                         Form 8-K Disclosure Information

Item on Form 8-K                             Party Responsible
--------------------------------------------------------------------------------
Item 1.01- Entry into a Material             All parties to the Pooling and
         Definitive Agreement                Servicing Agreement, each
                                             Servicer, the Custodian and, if
                                             applicable, the Special Servicer,
                                             as to each agreement to which it is
                                             a party

Item 1.02- Termination of a Material         All parties to the Pooling and
         Definitive Agreement                Servicing Agreement, each
                                             Servicer, the Custodian and, if
                                             applicable, the Special Servicer,
                                             as to each agreement to which it is
                                             a party

Item 1.03- Bankruptcy or Receivership        (i) Depositor, as to itself, the
                                             sponsor, any 1100(d)(1) party,
                                             any significant obligor, any
                                             credit enhancement provider or
                                             derivative counterparty and any
                                             other transaction party, to the
                                             extent known to the Depositor,
                                             (ii) Trustee, as to itself,
                                             (iii) each Servicer as to
                                             itself, (iv) Master Servicer, as
                                             to itself and any other
                                             transaction party, to the extent
                                             known to the Master Servicer

Item 2.04- Triggering Events that            Master Servicer
         Accelerate or Increase a
         Direct Financial Obligation
         or an Obligation under an
         Off-Balance Sheet Arrangement

Item 3.03- Material Modification to          Master Servicer
         Rights of Security Holders

Item 5.03- Amendments of Articles of         Master Servicer
         Incorporation or Bylaws;
         Change of Fiscal Year

Item 6.01- ABS Informational and             Depositor
         Computational Material

Item 6.02- Change of Servicer or             Servicer, Master Servicer
         Master Servicer

Item 6.03- Change in Credit                  Depositor/Master Servicer
         Enhancement or External
         Support

Item 6.04- Failure to Make a Required        Master Servicer
         Distribution

Item 6.05- Securities Act Updating           Depositor
         Disclosure

Item 7.01- Reg FD Disclosure                 Depositor

Item 8.01-Other Events                       Depositor, Master Servicer

Item 9.01                                    Depositor, Master Servicer

<PAGE>

                                    EXHIBIT V

                       Additional Disclosure Notification


**SEND VIA FAX TO 410-715-2380 AND VIA EMAIL TO
CTS.SEC.NOTIFICATIONS@WELLSFARGO.COM AND VIA OVERNIGHT MAIL TO THE ADDRESS
IMMEDIATELY BELOW**

Wells Fargo Bank, N.A., as Master Servicer
9062 Old Annapolis Road
Columbia, Maryland 21045
Attn: Corporate Trust Services- WFMBS 2007-4--SEC REPORT PROCESSING


RE:**[Additional Form [10-D][10-K] Disclosure][Form 8-K Disclosure
Information]** Required


Ladies and Gentlemen:

            In accordance with Section [_] of the Pooling and Servicing
Agreement, dated as of March 28, 2007, among Wells Fargo Asset Securities
Corporation, as depositor, Wells Fargo Bank, N.A., as master servicer, and HSBC
Bank USA, National Association, as trustee, the undersigned, as [__________],
hereby notifies you that certain events have come to our attention that [will]
[may] need to be disclosed on Form [10-D][10-K][8-K].

Description of [Additional Form [10-D][10-K] Disclosure][Form 8-K Disclosure
Information]:


List of any Attachments hereto to be included in the Additional Form
[10-D][10-K] Disclosure][Form 8-K Disclosure Information]:


            Any inquiries related to this notification should be directed to
[_______________], phone number: [________]; email address: [___________].

                                                [NAME OF PARTY],
                                                as [role]

                                                By:
                                                   -----------------------------
                                                   Name:
                                                   Title:

<PAGE>

                                    EXHIBIT W

                           Yield Maintenance Agreement

      [Included as Exhibit 10.3 to the Current Report on Form 8-K pursuant
            to which this Pooling and Servicing Agreement is filed.]


<PAGE>

                                    EXHIBIT X

                   FORM OF YIELD MAINTENANCE AGREEMENT LETTER

                                [______________]
                                [______________]
                                [______________]

                                                           [__________ __, ____]

Wells Fargo Asset Securities Corporation
7430 New Technology Way
Frederick, Maryland  21703

      Re:   Wells Fargo Asset Securities Corporation; Mortgage Pass-Through
            Certificates, Series 2007-4

Ladies and Gentlemen:

      [________] hereby acknowledges to you that the fair value of the Yield
Maintenance Agreement (as defined in the Prospectus Supplement dated [________]
for the Certificates) as of the date of pricing of the Class [__] Certificates,
which value will be used for tax reporting purposes, was either:

Check the appropriate box:

[_]   $____________

         OR

[_]   a nominal value.

                                    Very truly yours,

                                    [_________________]

                                    By:
                                       ---------------------------------
                                       Name:
                                       Title: