Document:

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                                                                   Exhibit 10.21

                 FLEET NATIONAL BANK LIQUID COLLATERAL AGREEMENT

                          DATED AS OF NOVEMBER 7, 2001

                                      AMONG

                          HUMAN GENOME SCIENCES, INC.,
                                   AS LESSEE,

                          GENOME STATUTORY TRUST 2001A,
                                   AS LESSOR,

                              FLEET NATIONAL BANK,
                    AS FLEET NATIONAL BANK COLLATERAL AGENT,

                                       AND

                    THE PERSONS LISTED ON SCHEDULE I HERETO,
                                AS BENEFICIARIES

[An identical liquid collateral agreement was also entered into between First
Union National Bank as First Union Collateral Agent, Human Genome Sciences, Inc.
as lessee, the Genome Statutory Trust 2001A as lessor, and the persons listed on
Schedule I of that agreement.]

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                 FLEET NATIONAL BANK LIQUID COLLATERAL AGREEMENT

                THIS FLEET NATIONAL BANK LIQUID COLLATERAL AGREEMENT, dated as
of November 7, 2001 (this "Agreement"), by and among HUMAN GENOME SCIENCES, INC.
("Lessee"), GENOME STATUTORY TRUST 2001A, a Connecticut statutory trust
("Lessor"), FLEET NATIONAL BANK ("Fleet National Bank Collateral Agent"), as
Fleet National Bank Collateral Agent for the benefit of the Beneficiaries, and
the Persons listed on Schedule I hereto (the "Beneficiaries").

                              W I T N E S S E T H:

                WHEREAS, pursuant to the Participation Agreement, Ground Lessor
and Ground Lessee have entered into the Ground Lease pursuant to which Ground
Lessee has leased the Traville Site from Ground Lessor;

                WHEREAS, pursuant to the Lease, Lessor has leased the Properties
to Lessee;

                WHEREAS, in connection with the Participation Agreement, Lessee
has opened the Account (Fleet National Bank) with the Fleet National Bank
Custodian, in the name of Lessee, subject to a first priority lien and security
interest in favor of Lessor, to hold Securities (which initially are the
Securities described in Exhibit A hereto);

                WHEREAS, in connection herewith, Lessee, Lessor, the Fleet
National Bank Collateral Agent, the Beneficiaries and the Fleet National Bank
Custodian are entering into the Fleet National Bank Custody Agreement dated as
of the Documentation Date;

                WHEREAS, as a material inducement for Lessor to enter into the
Participation Agreement and the other Operative Documents to which it is a
party, Lessee has agreed to execute and deliver this Agreement for the purpose
of securing the Secured Lessee Obligations and for the purpose of subjecting the
Fleet National Bank Liquid Collateral to the Lien of this Agreement as security
for the payment and performance of the Secured Lessee Obligations; and

                WHEREAS, as a material inducement for the Beneficiaries to enter
into the Participation Agreement and the other Operative Documents to which they
are party, Lessor has agreed to execute and deliver this Agreement for the
purpose of securing the Secured Lessor Obligations and for the purpose of
subjecting to the extent of the Lessor's interest therein the Fleet National
Bank Liquid Collateral to the Lien of this Agreement as security for the payment
and performance of the Secured Lessor Obligations.

                IT IS HEREBY COVENANTED AND DECLARED by and between the parties
hereto and their respective successors and assigns that the terms upon which the
Fleet National Bank Liquid Collateral shall be held and used are as follows:

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                                FLEET NATIONAL BANK LIQUID COLLATERAL AGREEMENT

                                    ARTICLE 1

                           DEFINITIONS, INTERPRETATION

                1.1     CERTAIN DEFINITIONS

                (a)     Subject to the following sentence, Appendix A to the
Participation Agreement applies (including as to rules of usage) to this
Agreement. Except as contained in Section 1.1(b), capitalized terms used herein
shall have the respective meanings assigned thereto in Appendix A to the
Participation Agreement for all purposes hereof.

                (b)     In this Agreement the following capitalized terms have
the following respective meanings:

                "ACCOUNT (FLEET NATIONAL BANK)" means Securities Account number
        _____ of Lessee maintained with the Fleet National Bank Custodian (or
        any successor custodian) subject to the Liens and security interests
        granted hereunder, together with all subaccounts thereto and any new
        accounts and subaccounts established and maintained in replacement
        thereof with the Fleet National Bank Custodian or any successor
        custodian.

                "ADDITIONAL COLLATERAL DELIVERY DATE" means, with respect to
        each Additional Collateral Demand, the day on or before the fifth
        Business Day following the making of an Additional Collateral Demand or
        if one or more Additional Collateral Demands are outstanding and the
        aggregate amount of the Pledged Security required to be transferred to
        the Account (Fleet National Bank) exceeds $5,000,000, then with respect
        to all outstanding transfers of Pledged Securities, on the Business Day
        next following the Business Day when the aggregate amounts required to
        be transferred to such Account (Fleet National Bank) first exceeds
        $5,000,000.

                "ADDITIONAL COLLATERAL DEMAND" has the meaning set forth in
        Section 2.5(a)(i).

                "ADDITIONAL COLLATERAL DEMAND DATE" has the meaning set forth in
        Section 2.5(a)(iii).

                "ADDITIONAL LIQUID COLLATERAL" has the meaning set forth in
        Section 2.5(a)(i).

                "BENEFICIARIES" has the meaning set forth in the first paragraph
        of this Agreement and shall include the successors and permitted assigns
        of the Beneficiaries.

                "ENFORCEMENT EVENT" means a Lease Event of Default or a
        Construction Agency Event of Default.

                "ENFORCEMENT NOTICE" means a notice from the Fleet National Bank
        Collateral Agent to the Fleet National Bank Custodian in substantially
        the form of Exhibit A hereto.

                "ENTITLEMENT ORDER" has the meaning set forth in Section
        8-102(a)(8) of the Uniform Commercial Code and shall include, without
        limitation, any Enforcement Notice from the Fleet National Bank
        Collateral Agent.

                                       2
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                                 FLEET NATIONAL BANK LIQUID COLLATERAL AGREEMENT

                "FINANCIAL ASSET" has the meaning set forth in Section
        8-102(a)(9) of the Uniform Commercial Code.

                "FLEET NATIONAL BANK COLLATERAL AGENT" means Fleet National Bank
        Collateral Agent and shall include the successors and permitted assigns
        of Fleet National Bank Collateral Agent.

                "FLEET NATIONAL BANK CUSTODIAN" means the Fleet National Bank
        Collateral Agent or any successor custodian appointed pursuant to the
        Fleet National Bank Custody Agreement.

                "FLEET NATIONAL BANK CUSTODY AGREEMENT" means the Fleet National
        Bank Custody Agreement, dated as of November 7, 2001, among Lessee,
        Lessor, the Fleet National Bank Collateral Agent, the Beneficiaries and
        the Fleet National Bank Custodian.

                "FLEET NATIONAL BANK LIQUID COLLATERAL" has the meaning set
        forth in Section 2.1(a)(i).

                "INVESTMENT PROPERTY" has the meaning set forth in Section
        9-102(a)(49) of the Uniform Commercial Code.

                "PARTICIPATION AGREEMENT" means the Participation Agreement,
        dated as of November 7, 2001, among Lessee, as Lessee and Construction
        Agent, Traville LLC, as Ground Lessor, Lessor, as Ground Lessee and
        Lessor, BancBoston Leasing Investments Inc. and First Union National
        Bank, as Investors, EagleFunding Capital Corporation, as Lender, Fleet
        Securities, Inc., as Administrator, Fleet National Bank and First Union
        National Bank, as Liquidity Providers, Fleet National Bank, as Fleet
        National Bank Collateral Agent, First Union National Bank, as First
        Union Collateral Agent and Fleet National Bank, as Administrative Agent
        and Liquidity Agent.

                "PLEDGED SECURITIES" means the Securities credited to the
        Account (Fleet National Bank) from time to time, less any Pledged
        Securities released to Lessee in accordance with the Fleet National Bank
        Liquid Collateral Agreement and the Participation Agreement.

                "PROCEEDS" of the Fleet National Bank Liquid Collateral has the
        meaning given in Section 9-102 of the Uniform Commercial Code and shall
        include cash, securities and other property realized in respect of, and
        distributions in kind of, the Fleet National Bank Liquid Collateral, as
        applicable.

                "SECURED LESSEE OBLIGATIONS" means all obligations of Lessee now
        or hereafter existing under the Participation Agreement, the Lease and
        each other Operative Document, whether for principal, interest, costs,
        fees, expenses or otherwise, and all other obligations of Lessee to
        Lessor and the Beneficiaries, howsoever created, arising or evidenced,
        whether direct or indirect, absolute or contingent or now or hereafter
        existing or due or to become due under the Operative Documents.

                                       3
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                                 FLEET NATIONAL BANK LIQUID COLLATERAL AGREEMENT

                "SECURED LESSOR OBLIGATIONS" means all obligations of Lessor now
        or hereafter existing under the Participation Agreement and each other
        Operative Document, whether for principal, interest, costs, fees,
        expenses or otherwise, and all other obligations of Lessor to the
        Beneficiaries, howsoever created, arising or evidenced, whether direct
        or indirect, absolute or contingent or now or hereafter existing or due
        or to become due.

                "SECURITIES" has the meaning given that term in Section
        8-102(a)(15) of the Uniform Commercial Code.

                "SECURITIES ACCOUNT" has the meaning set forth in Section
        8-501(a) of the Uniform Commercial Code.

                "SECURITIES INTERMEDIARY" has the meaning set forth in Section
        8-102(a)(14) of the Uniform Commercial Code.

                "SECURITY ENTITLEMENT" has the meaning set forth in Section
        357.2 of the Treasury Regulations and Section 8-102(a)(17) of the
        Uniform Commercial Code.

                "SETTLEMENT DATE" has the meaning set forth in Section
        2.5(a)(iv).

                "TREASURY REGULATIONS" means 31 CFR Part 357, as amended by
        regulations published at 61 Fed. Reg. 43626 (August 23, 1996) and as may
        be amended from time to time by any subsequent regulations.

                "UNIFORM COMMERCIAL CODE" and "UCC" means the Uniform Commercial
        Code, as amended, as in effect in the State of New York from time to
        time.

                                    ARTICLE 2

                              GRANTING OF SECURITY

                2.1     GRANTING OF SECURITY INTERESTS

                (a)     Granting of Security Interest from Lessee to Lessor

                (i)     Lessee has established and shall maintain at all times,
        so long as there are Secured Lessee Obligations outstanding, the Account
        (Fleet National Bank) with the Fleet National Bank Custodian, which
        Account (Fleet National Bank) shall be a Securities Account, shall be in
        the name of Lessee but subject to the first priority security interest
        of the Fleet National Bank Collateral Agent for the benefit of the
        Beneficiaries and itself, and shall have the designation as provided in
        the Fleet National Bank Custody Agreement. As security for the due,
        prompt and complete payment and performance of the Secured Lessee
        Obligations, Lessee hereby unconditionally, irrevocably and presently
        conveys, mortgages, assigns, transfers, and pledges to Lessor, and
        hereby grants to Lessor, a first Lien on, and a first priority security
        interest in, all right, title and interest in, to and under the Pledged
        Securities; the Account (Fleet National Bank) and all funds, cash and
        cash equivalents, Financial Assets, Investment Property and any other
        property from time to time credited or required to be credited thereto
        including any Additional

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                                 FLEET NATIONAL BANK LIQUID COLLATERAL AGREEMENT

        Liquid Collateral transferred to the Account (Fleet National Bank)
        pursuant to Section 2.5(a) (and all certificates, cash balances and
        instruments from time to time representing or evidencing the same); all
        notes, certificates of deposit, deposit amounts, checks and other
        investments from time to time hereafter delivered to or otherwise
        possessed by the Fleet National Bank Custodian in substitution for any
        or all of the foregoing; all rights, claims, and causes of action, if
        any, that Lessee may have against the Fleet National Bank Custodian or
        any other person in respect of the foregoing; all interest, dividends,
        cash, instruments and other property from time to time received,
        receivable, or distributed in respect of any or all of the foregoing;
        all Security Entitlements of Lessee in or with respect to any and all of
        the foregoing including all Security Entitlements credited to or held in
        the Account (Fleet National Bank); and all Proceeds of any and all of
        the foregoing, whether now existing or hereafter acquired (collectively,
        the "Fleet National Bank Liquid Collateral").

                (ii)    To perfect the security interest granted by Lessee to
        Lessor in the Fleet National Bank Liquid Collateral hereunder, Lessee
        hereby gives control over the Fleet National Bank Liquid Collateral to
        Lessor and shall file financing statements in respect of the Fleet
        National Bank Liquid Collateral in the manner and at the place or places
        set forth in the Uniform Commercial Code and make such other filing or
        take such other measures as may be prescribed by Applicable Law or
        reasonably requested by Lessor, the Fleet National Bank Collateral Agent
        or the Beneficiaries.

                (iii)   Lessee will cause to be done, executed, acknowledged and
        delivered all such further acts, conveyances and assurances as Lessor,
        the Fleet National Bank Collateral Agent or the Beneficiaries shall
        reasonably require for accomplishing the purposes of this Agreement, and
        which are necessary or desirable to continue the perfection and priority
        of the Liens and security interests granted under this Agreement.

                (iv)    Lessee agrees for the benefit of Lessor and the
        Beneficiaries, at no expense to Lessor, the Fleet National Bank
        Collateral Agent or the Beneficiaries, to defend Lessor's and the Fleet
        National Bank Collateral Agent's security interest in and to the Fleet
        National Bank Liquid Collateral against the claims of any Person and to
        ensure that Lessor and the Fleet National Bank Collateral Agent shall
        have at all times pursuant to this Agreement a first priority perfected
        Lien on and security interest in the Fleet National Bank Liquid
        Collateral, subject to no prior or equal Lien whatsoever.

                (v)     All rights of Lessor hereunder, and all obligations of
        Lessee hereunder, shall be absolute and unconditional irrespective of:

                        (1)     any lack of validity or enforceability of this
        Agreement or any Operative Document;

                        (2)     any change in the time, manner or place of
        payment of, or any other term of, all or any of the Secured Lessee
        Obligations, or any amendment or waiver of or any consent to any
        departure from this Agreement or the Operative Documents;

                                       5
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                                 FLEET NATIONAL BANK LIQUID COLLATERAL AGREEMENT

                        (3)     any taking, exchange, release or non-perfection
        of any other Fleet National Bank Liquid Collateral or taking, release or
        amendment or waiver of or consent to departure from any guaranty or
        indemnity for all or any of the Secured Lessee Obligations; and

                        (4)     any manner of application of Fleet National Bank
        Liquid Collateral, or Proceeds thereof, to all or any of the Secured
        Lessee Obligations, or any manner of sale or disposition of any Fleet
        National Bank Liquid Collateral for all or any of the Secured Lessee
        Obligations or any other assets of Lessee.

                (vi)    Lessee agrees, for the benefit of Lessor, the Fleet
        National Bank Collateral Agent and the Beneficiaries, that it shall not
        be entitled to withdraw, liquidate, sell, convey, endorse, negotiate, or
        in any way dispose of, or create, incur, or permit to exist any pledge,
        mortgage, Lien, charge, encumbrance or security interest whatsoever, or
        cause any of the foregoing to occur in or with respect to, any of the
        Fleet National Bank Liquid Collateral, any interest therein or any cash
        or other property held and maintained in or credited to the Account
        (Fleet National Bank).

                (vii)   Except as expressly set forth herein or in the other
        Operative Documents, Lessee hereby expressly waives diligence,
        presentment, demand for payment, protest, any requirement that any right
        or power be exhausted or any action be taken against any Person, all
        notices (whether non-payment by Lessee or any other Person, dishonor,
        protest or otherwise) with respect to any of the Secured Lessee
        Obligations and notice of acceptance of this Agreement.

                (viii)  Subject to Sections 2.1(b)(ii) and 2.1(b)(viii), all
        cash and cash equivalents deposited in or credited to the Account (Fleet
        National Bank) from time to time shall be under the sole dominion and
        control of Lessor and held by the Fleet National Bank Custodian pursuant
        to the Fleet National Bank Custody Agreement as Lessor's agent and
        bailee, and Lessor shall have the sole right to make or direct
        withdrawals of cash or cash equivalents from the Account (Fleet National
        Bank).

                (b)     Granting of Security Interest from Lessor to the Fleet
National Bank Collateral Agent

                (i) As security for the due, prompt and complete payment and
        performance of the Secured Lessor Obligations, Lessor hereby
        unconditionally, irrevocably and presently conveys, mortgages, assigns,
        transfers, and pledges to the Fleet National Bank Collateral Agent, for
        the benefit of the Beneficiaries, and hereby grants to the Fleet
        National Bank Collateral Agent, for the benefit of the Beneficiaries, a
        first Lien on, and a first priority security interest in, all of
        Lessor's right, title and interest in, to and under the Fleet National
        Bank Liquid Collateral, the Pledged Securities; the Account (Fleet
        National Bank) and all funds, cash and cash equivalents, Financial
        Assets, Investment Property and any other property from time to time
        credited or required to be credited thereto including any Additional
        Liquid Collateral transferred to the Account (Fleet National Bank)
        pursuant to Section 2.5(a) (and all certificates, cash balances and
        instruments from time to time representing or evidencing the same); all
        notes, certificates of deposit,

                                       6
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                                 FLEET NATIONAL BANK LIQUID COLLATERAL AGREEMENT

        deposit amounts, checks and other investments from time to time
        hereafter delivered to or otherwise possessed by the Fleet National Bank
        Custodian in substitution for any or all of the foregoing; all rights,
        claims, and causes of action, if any, that Lessee or Lessor may have
        against the Fleet National Bank Custodian or any other person in respect
        of the foregoing; all interest, dividends, cash, instruments and other
        property from time to time received, receivable, or distributed in
        respect of any or all of the foregoing; all Security Entitlements of
        Lessee or Lessor in or with respect to any and all of the foregoing
        including all Security Entitlements credited to or held in the Account
        (Fleet National Bank); and all Proceeds of any and all of the foregoing,
        whether now existing or hereafter acquired.

                (ii)    To perfect the security interest granted by Lessor to
        the Fleet National Bank Collateral Agent in the Fleet National Bank
        Liquid Collateral hereunder, Lessor hereby gives control over the Fleet
        National Bank Liquid Collateral to the Fleet National Bank Collateral
        Agent and shall file financing statements in respect of the Fleet
        National Bank Liquid Collateral in the manner and at the place or places
        set forth in the Uniform Commercial Code and make such other filing or
        take such other measures as may be prescribed by Applicable Law or
        reasonably requested by the Fleet National Bank Collateral Agent or the
        Beneficiaries.

                (iii)   Lessor will cause to be done, executed, acknowledged and
        delivered all such further acts, conveyances and assurances as the Fleet
        National Bank Collateral Agent or the Beneficiaries shall reasonably
        require for accomplishing the purposes of this Agreement, and which are
        necessary or desirable to continue the perfection and priority of the
        Liens and security interests granted under this Agreement.

                (iv)    Intentionally Omitted.

                (v)     All rights of the Fleet National Bank Collateral Agent
        and the Beneficiaries hereunder, and all obligations of Lessor
        hereunder, shall be absolute and unconditional irrespective of:

                        (1)     any lack of validity or enforceability of this
        Agreement or any Operative Document;

                        (2)     any change in the time, manner or place of
        payment of, or any other term of, all or any of the Secured Lessor
        Obligations, or any amendment or waiver of or any consent to any
        departure from this Agreement or the Operative Documents;

                        (3)     any taking, exchange, release or non-perfection
        of any other Fleet National Bank Liquid Collateral or taking, release or
        amendment or waiver of or consent to departure from any guaranty or
        indemnity for all or any of the Secured Lessor Obligations; and

                        (4)     any manner of application of Fleet National Bank
        Liquid Collateral, or Proceeds thereof, to all or any of the Secured
        Lessor Obligations, or any manner of sale or disposition of any Fleet
        National Bank Liquid Collateral for all or any of the Secured Lessor
        Obligations or any other assets of Lessor.

                                       7
<PAGE>
                                 FLEET NATIONAL BANK LIQUID COLLATERAL AGREEMENT

                (vi)    Lessor agrees, for the benefit of the Beneficiaries,
        that it shall not be entitled to withdraw, liquidate, sell, convey,
        endorse, negotiate, or in any way dispose of, or create, incur, or
        permit to exist any pledge, mortgage, Lien, charge, encumbrance or
        security interest whatsoever, or cause any of the foregoing to occur in
        or with respect to, any of the Fleet National Bank Liquid Collateral,
        any interest therein or any cash or other property held and maintained
        in or credited to the Account (Fleet National Bank).

                (vii)   Except as expressly set forth herein or in the other
        Operative Documents, Lessor hereby expressly waives diligence,
        presentment, demand for payment, protest, any requirement that any right
        or power be exhausted or any action be taken against any Person, all
        notices (whether non-payment by Lessor or any other Person, dishonor,
        protest or otherwise) with respect to any of the Secured Lessor
        Obligations and notice of acceptance of this Agreement.

                (viii)  Anything to the contrary herein notwithstanding, all
        cash and cash equivalents deposited in or credited to the Account (Fleet
        National Bank) from time to time shall be under the sole dominion and
        control of the Fleet National Bank Collateral Agent and held by the
        Fleet National Bank Custodian pursuant to the Fleet National Bank
        Custody Agreement as the Fleet National Bank Collateral Agent's agent
        and bailee, and the Fleet National Bank Collateral Agent shall have the
        sole right to make or direct withdrawals of cash or cash equivalents
        from the Account (Fleet National Bank).

                2.2     REMEDIES

                The Fleet National Bank Collateral Agent may, upon the
occurrence and continuance of an Enforcement Event and the delivery of an
Enforcement Notice to the Fleet National Bank Custodian by the Fleet National
Bank Collateral Agent, and without the consent of Lessee or any other Person,
exercise certain remedies with respect to the Fleet National Bank Liquid
Collateral as provided herein, including, but not limited to, directing the
Fleet National Bank Custodian to sell or cause to be sold an amount of the Fleet
National Bank Liquid Collateral and otherwise acting in all respects as the
owner of the Fleet National Bank Liquid Collateral.

                2.3     PLEDGORS REMAIN LIABLE

                Anything to the contrary herein notwithstanding, (i) Lessee
shall remain liable under Operative Documents to Lessor and Lessor shall remain
liable under the Operative Documents to the Beneficiaries, each to the extent
set forth therein to perform all of their duties and obligations, if any,
thereunder to the same extent as if this Agreement had not been executed and the
pledges hereunder had not been made, (ii) the exercise by Lessor or the Fleet
National Bank Collateral Agent of any of their rights hereunder shall not
release Lessee or Lessor from any of their duties or obligations, if any, under
the Operative Documents, except to the extent that such obligations are
satisfied by the payment of an amount hereunder or pursuant to the Fleet
National Bank Custody Agreement. The execution and delivery of this Agreement
shall not in any way diminish the respective rights and obligations of Lessee,
Lessor or the Fleet National Bank Collateral Agent (or any other party thereto)
under the Operative Documents.

                                       8
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                                 FLEET NATIONAL BANK LIQUID COLLATERAL AGREEMENT

                2.4     INSTRUCTIONS REGARDING THE ACCOUNT (FLEET NATIONAL BANK)

                It is hereby acknowledged and agreed that pursuant to the Fleet
National Bank Custody Agreement, other than as expressly set forth therein and
herein, only the Fleet National Bank Collateral Agent is entitled to give
instructions and Entitlement Orders to the Fleet National Bank Custodian with
respect to the Account (Fleet National Bank) , any and all Securities credited
to the Account (Fleet National Bank) and any other Fleet National Bank Liquid
Collateral.

                2.5     ADDITIONAL FLEET NATIONAL BANK LIQUID COLLATERAL

                (a)    (i)      Pursuant to the Participation Agreement, the
Fleet National Bank Collateral Agent shall have the right at any time, and from
time to time upon delivery to Lessee of a demand given by telephone or fax (and
confirmed in writing) (a "Additional Collateral Demand"), to require Lessee to
transfer additional Permitted Investments (the "Additional Liquid Collateral")
to the Account (Fleet National Bank) by the Additional Collateral Delivery Date
to ensure that the Adjusted Market Value, in the case of Properly Margined
Liquid Collateral, and the Fair Market Value, in the case of Non-Properly
Margined Liquid Collateral of Fleet National Bank Liquid Collateral in which
Lessor and the Fleet National Bank Collateral Agent have a first priority
perfected security interest shall be greater than or equal to the applicable
Required Liquid Collateral Amount for the Fleet National Bank Liquid Collateral;
provided, that after taking into account a transfer of Pledged Securities the
Account (Fleet National Bank) shall satisfy and at all times thereafter satisfy
the Concentration Limits.

                (ii)    Without limiting Section 2.5(a)(i) above Lessee shall
        transfer such Additional Liquid Collateral to the Account (Fleet
        National Bank) by the Additional Collateral Delivery Date to ensure
        that, the Adjusted Market Value, in the case of Properly Margined Liquid
        Collateral, and the Fair Market Value, in the case of Non-Properly
        Margined Liquid Collateral of Fleet National Bank Liquid Collateral in
        which Lessor and the Fleet National Bank Collateral Agent have a first
        priority perfected security interest shall be greater than or equal to
        the applicable Required Liquid Collateral Amount for the Fleet National
        Bank Liquid Collateral.

                (b)     Pursuant to the account agreements entered into with the
Fleet National Bank, Fleet National Bank Custodian shall have the right to
direct the reinvestment of any Pledged Securities credited to the Account (Fleet
National Bank) upon the maturity of such Pledged Securities or prior thereto.

                (c)     The parties hereto acknowledge and agree that (i) any
Permitted Investments transferred to the Account (Fleet National Bank) pursuant
to Sections 2.5(a) or 2.5(b) or otherwise shall be deemed Pledged Securities for
the purposes of this Agreement, (ii) on any transfer date, the Fleet National
Bank Collateral Agent shall instruct Lessee and the Fleet National Bank
Custodian to take or cause to be taken, and Lessee and the Fleet National Bank
Custodian shall take or cause to be taken, at Lessee's sole cost and expense,
such action as is necessary create in Lessor a valid perfected first priority
security interest on such date in such Pledged Securities, and (iii) on any
transfer date, the Fleet National Bank Collateral Agent shall instruct Lessee,
Lessor and the Fleet National Bank Custodian to take or cause to be taken, and

                                       9
<PAGE>
                                 FLEET NATIONAL BANK LIQUID COLLATERAL AGREEMENT

Lessee, Lessor and the Fleet National Bank Custodian shall take or cause to be
taken, at Lessee's sole cost and expense, such action as is necessary create in
the Fleet National Bank Collateral Agent a valid perfected first priority
security interest on such date in Lessor's right, title and interest in, to and
under such Pledged Securities. Without limiting the foregoing, the Fleet
National Bank Collateral Agent is hereby authorized to complete Exhibit A hereto
upon acquisition of such Pledged Securities.

                                   ARTICLE 3

                               COVENANTS OF LESSEE

                3.1     NO SET-OFF

                (a)     Lessee, Lessor, the Fleet National Bank Collateral Agent
and the Beneficiaries acknowledge that the Fleet National Bank Custodian may
from time to time have other relationships with Lessee, Lessor, the Fleet
National Bank Collateral Agent or the Beneficiaries that are not related to the
transactions contemplated by this Agreement or the Participation Agreement and
not secured hereunder.

                (b)     No set-off, counterclaim, reduction or diminution of any
obligation, or any defense of any kind or nature (other than complete
performance by Lessee of its obligations hereunder) which Lessee may have to
assert against Lessor, the Fleet National Bank Collateral Agent or any
Beneficiary shall be available hereunder to, or shall be asserted by, Lessee in
any action arising out of the transactions contemplated hereby.

                (c)     Lessee covenants that it shall not terminate the Fleet
National Bank Custody Agreement without the Beneficiaries' express prior written
consent, other than in accordance with the terms thereof.

                3.2     FURTHER TRANSFERS

                As long as the security interest in and the Lien on the Fleet
National Bank Liquid Collateral created hereunder in favor of Lessor and the
Fleet National Bank Collateral Agent shall not have been discharged or released,
Lessee shall not sell, transfer, convey, assign, grant a Lien on or security
interest in, or otherwise dispose of the Fleet National Bank Liquid Collateral,
or any part thereof, without the prior written consent of the Fleet National
Bank Collateral Agent except as provided herein or in the Fleet National Bank
Custody Agreement.

                                   ARTICLE 4

                         COVENANTS OF LESSOR AND LESSEE

                4.1     NO SET-OFF

                (a)     No set-off, counterclaim, reduction or diminution of any
obligation, or any defense of any kind or nature (other than complete
performance by Lessor of its obligations hereunder) which Lessor may have to
assert against the Fleet National Bank Collateral Agent or

                                       10
<PAGE>
                                 FLEET NATIONAL BANK LIQUID COLLATERAL AGREEMENT

any Beneficiary shall be available hereunder to, or shall be asserted by, Lessor
in any action arising out of the transactions contemplated hereby.

                (b)     Lessor covenants that it shall not terminate the Fleet
National Bank Custody Agreement without the Beneficiaries' express prior written
consent, other than in accordance with the terms thereof.

                4.2     FURTHER TRANSFERS

                As long as the security interest in and the Lien on the Fleet
National Bank Liquid Collateral created hereunder in favor of the Fleet National
Bank Collateral Agent shall not have been discharged or released, Lessor shall
not sell, transfer, convey, assign, grant a Lien on or security interest in, or
otherwise dispose of the Fleet National Bank Liquid Collateral, or any part
thereof, without the prior written consent of the Fleet National Bank Collateral
Agent except as provided herein or in the Fleet National Bank Custody Agreement.

                                   ARTICLE 5

                                    REMEDIES

                5.1     REMEDIES UPON ENFORCEMENT EVENT

                (a)     Lessee and Lessor agree that if any Enforcement Event
shall have occurred and be continuing the Fleet National Bank Collateral Agent
may exercise in respect of the Fleet National Bank Liquid Collateral, in
addition to other rights and remedies provided for herein or otherwise available
to it, all the rights and remedies of a secured party under the UCC (whether or
not the UCC applies to the Fleet National Bank Liquid Collateral at issue), and
the Fleet National Bank Collateral Agent may also, without notice except as
specified below, sell the Fleet National Bank Liquid Collateral or any part
thereof in one or more parcels at public or private sale, or at any of the Fleet
National Bank Collateral Agent's offices or elsewhere, for cash, on credit or
for future delivery, and upon such other terms as Collateral Agent may deem
commercially reasonable. Lessee and Lessor agrees that, to the extent notice of
sale shall be required by law, at least five Business Days' notice to Lessee and
Lessor of the time and place of any public sale or the time after which a
private sale is to be made shall constitute reasonable notification. The Fleet
National Bank Collateral Agent shall not be obligated to make any sale of Fleet
National Bank Liquid Collateral regardless of notice of sale having been given.
The Fleet National Bank Collateral Agent may adjourn any public or private sale
from time to time by announcement at the time and place fixed therefore and such
sale may, without further notice, be made at the time and place to which it was
so adjourned. The Fleet National Bank Collateral Agent shall be entitled to
consult with legal counsel and financial advisors in connection with the sale of
the Fleet National Bank Liquid Collateral and shall be protected in any
reasonable action or forbearance taken in connection with the advice of such
counsel or advisors.

                (b)     Each and every right, power and remedy given to the
Fleet National Bank Collateral Agent specifically or otherwise in this Agreement
shall be cumulative and shall be in addition to every other right, power and
remedy herein specifically given or now or hereafter existing at law, or under
the UCC, or otherwise in equity or by statute, and each and every right,

                                       11
<PAGE>
                                 FLEET NATIONAL BANK LIQUID COLLATERAL AGREEMENT

power and remedy whether specifically herein given or otherwise existing may be
exercised from time to time and as often and in such order as may be deemed
expedient by the Fleet National Bank Collateral Agent, and the exercise or the
beginning of the exercise of any power or remedy shall not be construed to be a
waiver of the right to exercise at the same time or thereafter any other right,
power or remedy. No delay or omission by the Fleet National Bank Collateral
Agent in the exercise of any right, remedy or power or in the pursuance of any
remedy shall impair any such right, power or remedy or be construed to be a
waiver of any default on the part of the Fleet National Bank Collateral Agent or
to be an acquiescence therein.

                (c)     In case the Fleet National Bank Collateral Agent shall
have instituted any proceeding to enforce any right, power or remedy under this
Agreement by foreclosure, entry or otherwise, and such proceedings shall have
been discontinued or abandoned for any reason or shall have been determined
adversely to the Fleet National Bank Collateral Agent, then and in every such
case the Fleet National Bank Collateral Agent, Lessee and Lessor shall, subject
to any determination in such proceedings, be restored to their former positions
and rights hereunder with respect to the Fleet National Bank Liquid Collateral,
and all rights, remedies and powers of the Fleet National Bank Collateral Agent
shall continue as if no such proceedings had been instituted.

                (d)     Lessee and Lessor agree, to the full extent that it may
lawfully so agree, that neither it nor any Person claiming through or under it
will set up, claim or seek to take advantage of any appraisement, valuation,
stay, extension or redemption law now or hereafter in force, in order to
prevent, hinder or delay the enforcement or foreclosure of this Agreement, or
the absolute sale of the Fleet National Bank Liquid Collateral or any part
thereof, or the final and absolute putting into possession thereof, immediately
after such sale, of the purchaser thereof, and each of Lessee and Lessor, for
itself and all who may at any time claim through or under it, hereby waives to
the full extent that it may be lawful so to do, the benefit of all such laws,
and any and all right to have any of the properties or assets comprising the
Fleet National Bank Liquid Collateral marshalled upon any such sale, and agrees
that, subject to the terms of the Fleet National Bank Custody Agreement, the
Fleet National Bank Collateral Agent or any court having jurisdiction to
foreclose the Lien hereof may sell the Fleet National Bank Liquid Collateral as
an entirety or in such portions as the Fleet National Bank Collateral Agent may
determine.

                (e)     The Fleet National Bank Collateral Agent will promptly
upon receipt of any proceeds from any sale of any Fleet National Bank Liquid
Collateral pursuant to this Section 5.1 deliver such proceeds to the
Administrative Agent for distribution in accordance with Article X of the
Participation Agreement.

                5.2     POWERS OF ATTORNEY

                (a)     Lessee hereby irrevocably appoints the Fleet National
Bank Collateral Agent the true and lawful attorney of Lessee (with full power of
substitution) in the name, place and stead of, and at the expense of, Lessee (i)
for any period for the purpose of signing documents and taking other action to
perfect Lessor's and the Fleet National Bank Collateral Agent's security
interest in the Fleet National Bank Liquid Collateral and (ii) solely in
connection with the enforcement of the rights and remedies provided herein and
in the Fleet

                                       12
<PAGE>
                                 FLEET NATIONAL BANK LIQUID COLLATERAL AGREEMENT

National Bank Custody Agreement upon the occurrence and during the continuation
of an Enforcement Event:

                (i)     to give any necessary receipts or acquittances for
        amounts collected or received thereunder;

                (ii)    to make all necessary transfers of any of the Fleet
        National Bank Liquid Collateral in connection with any sale or other
        disposition made pursuant hereto;

                (iii)   to execute and deliver for value all necessary or
        appropriate bills of sale, assignments and other instruments and
        agreements in connection with any such sale or other disposition, Lessee
        hereby ratifying and confirming all that such attorney (or any
        substitute) shall lawfully do hereunder and pursuant hereto; and

                (iv)    to sign any agreements, orders or other documents in
        connection with or pursuant to this Agreement (to the extent the same
        relate to the Fleet National Bank Liquid Collateral).

Nevertheless, if so requested by the Fleet National Bank Collateral Agent or a
purchaser, Lessee shall ratify and confirm to the extent it has the power to do
so, any such sale or other disposition by executing and delivering to the Fleet
National Bank Collateral Agent or such purchaser all proper bills of sale,
assignments, releases and other instruments as may be designated in any such
request.

                (b) Lessor hereby irrevocably appoints the Fleet National Bank
Collateral Agent the true and lawful attorney of Lessor (with full power of
substitution) in the name, place and stead of, and at the expense of, Lessor (i)
for any period for the purpose of signing documents and taking other action to
perfect the Fleet National Bank Collateral Agent's security interest in the
Fleet National Bank Liquid Collateral and (ii) solely in connection with the
enforcement of the rights and remedies provided herein and in the Fleet National
Bank Custody Agreement upon the occurrence and during the continuation of an
Enforcement Event:

                (i)     to give any necessary receipts or acquittances for
        amounts collected or received thereunder;

                (ii)    to make all necessary transfers of any of the Fleet
        National Bank Liquid Collateral in connection with any sale or other
        disposition made pursuant hereto;

                (iii)   to execute and deliver for value all necessary or
        appropriate bills of sale, assignments and other instruments and
        agreements in connection with any such sale or other disposition, Lessor
        hereby ratifying and confirming all that such attorney (or any
        substitute) shall lawfully do hereunder and pursuant hereto; and

                (iv)    to sign any agreements, orders or other documents in
        connection with or pursuant to this Agreement (to the extent the same
        relate to the Fleet National Bank Liquid Collateral).

                                       13
<PAGE>
                                 FLEET NATIONAL BANK LIQUID COLLATERAL AGREEMENT

Nevertheless, if so requested by the Fleet National Bank Collateral Agent or a
purchaser, Lessor shall ratify and confirm to the extent it has the power to do
so, any such sale or other disposition by executing and delivering to the Fleet
National Bank Collateral Agent or such purchaser all proper bills of sale,
assignments, releases and other instruments as may be designated in any such
request.

                                   ARTICLE 6

                          RELEASE OF SECURITY INTEREST

                6.1     This Agreement shall remain in full force and effect
until payment in full by the Lessee of the Lease Balance, Supplemental Rent,
including Break Costs and all other amounts due and owing by it under the
Operative Documents and the termination of the Commitments of the Participants,
provided, however, that this Agreement and the security interests created hereby
shall earlier terminate and this Agreement shall be of no further force or
effect upon any sale or other final disposition by the Fleet National Bank
Collateral Agent of all of the property constituting the Fleet National Bank
Liquid Collateral and the final distribution by Fleet National Bank Collateral
Agent of all monies or other property or proceeds constituting the Fleet
National Bank Liquid Collateral in accordance with the terms of the
Participation Agreement.

                6.2     Upon any termination of this Agreement pursuant to
Section 6.1, Lessor and the Fleet National Bank Collateral Agent shall execute
and deliver to or as directed in writing by Lessee, an appropriate instrument
terminating this Agreement and releasing the Fleet National Bank Liquid
Collateral and the Fleet National Bank Collateral Agent shall provide the Fleet
National Bank Custodian with written notice informing the Fleet National Bank
Custodian that the Secured Lessee Obligations have been fully discharged and
instructing the Fleet National Bank Custodian to release all funds on deposit in
the Account (Fleet National Bank) from the assignment and pledge.

                6.3     Except as otherwise provided in this Article 6, this
Agreement and the security interests created hereby shall continue in full force
and effect in accordance with the terms hereof.

                                   ARTICLE 7

                                  MISCELLANEOUS

                7.1     NOTICES

                Notices and other communications required or permitted to be
given or made under the terms of this Agreement shall be given in the manner set
forth in the Participation Agreement at the initial addresses (and any successor
address for notice may be provided in the manner set forth in the Participation
Agreement) set forth on Schedule II to the Participation Agreement.

                                       14
<PAGE>
                                 FLEET NATIONAL BANK LIQUID COLLATERAL AGREEMENT

                7.2     COUNTERPARTS

                This Agreement may be executed by the parties hereto in
separate counterparts, each of which when so executed and delivered shall be an
original, but all such counterparts shall together constitute but one and the
same instrument.

                7.3     CONTINUING SECURITY

                (a)     Except as provided in Article 6, the security
constituted by this Agreement with respect to the Secured Lessee Obligations
shall not be considered as satisfied by payment or satisfaction of any part of
the Secured Lessee Obligations but shall be a continuing security and extend to
cover any and all sums of money or other obligations which shall for the time
being constitute Secured Lessee Obligations and shall not be discharged or
prejudiced or affected in any way by time being given to Lessee or any other
Person or by any other indulgence or concession to Lessee or any other Person
granted by Lessor, Fleet National Bank Collateral Agent or any Beneficiary, by
the taking, holding, varying, non-enforcement or release by Lessor, the Fleet
National Bank Collateral Agent or any Beneficiary of any other security for all
or any of the Secured Lessee Obligations, by any other thing done or omitted or
neglected to be done by Lessor, Fleet National Bank Collateral Agent or any
Beneficiary or by any other dealing or thing including whatsoever that but for
this provision might operate to discharge any of the Secured Lessee Obligations
or to exonerate or discharge Lessee from its obligations hereunder or otherwise
affect the security hereby constituted.

                (b)     Except as provided in Article 6, the security
constituted by this Agreement with respect to the Secured Lessor Obligations
shall not be considered as satisfied by payment or satisfaction of any part of
the Secured Lessor Obligations but shall be a continuing security and extend to
cover any and all sums of money or other obligations which shall for the time
being constitute Secured Lessor Obligations and shall not be discharged or
prejudiced or affected in any way by time being given to Lessor or any other
Person or by any other indulgence or concession to Lessor or any other Person
granted by the Fleet National Bank Collateral Agent or any Beneficiary, by the
taking, holding, varying, non-enforcement or release by the Fleet National Bank
Collateral Agent or any Beneficiary of any other security for all or any of the
Secured Lessor Obligations, by any other thing done or omitted or neglected to
be done by the Fleet National Bank Collateral Agent or any Beneficiary or by any
other dealing or thing including whatsoever that but for this provision might
operate to discharge any of the Secured Lessor Obligations or to exonerate or
discharge Lessor from its obligations hereunder or otherwise affect the security
hereby constituted.

                7.4     AMENDMENTS

                This Agreement may be amended only by a consent in writing
signed by the parties hereto, and specifically identified as an amendment
hereto.

                7.5     SEVERABILITY

                Any provision of this Agreement which is invalid, illegal or
unenforceable in any jurisdiction shall, as to such jurisdiction, be ineffective
to the extent of such invalidity, illegality or unenforceability without
invalidating, prohibiting the observance of or rendering

                                       15
<PAGE>
                                 FLEET NATIONAL BANK LIQUID COLLATERAL AGREEMENT

unenforceable the remaining provisions hereof, and any such invalidity,
illegality or unenforceability in any jurisdiction shall not invalidate,
prohibit the observance of or render unenforceable such provision in any other
jurisdiction.

                7.6     GOVERNING LAW

                THIS AGREEMENT SHALL IN ALL RESPECTS BE GOVERNED BY AND
CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK (INCLUDING
SECTION 5-1401 AND 5-1402 OF THE NEW YORK GENERAL OBLIGATIONS LAW BUT EXCLUDING
ALL OTHER CHOICE-OF-LAW AND CONFLICTS-OF-LAWS RULES). THE PARTIES HERETO AGREE
THAT THE STATE OF NEW YORK IS THE JURISDICTION OF THE COLLATERAL AGENT FOR
PURPOSES OF PART 3 OF ARTICLE 9 OF THE UCC.

                Any suit, action or proceeding against the parties hereto with
respect to this Agreement, or any other Operative Document or any judgment
entered by any court in respect thereof may be brought in the Supreme Court of
the State of New York, County of New York, or the United States District Court
for the Southern District of New York (provided that such jurisdiction shall be
non-exclusive). The provisions of Sections 12.13 and 12.14 of the Participation
Agreement and related definitions are incorporated herein by reference, mutatis
mutandis.

                7.7     OWNER

                Lessee acknowledges its ownership of, and its responsibility
(as opposed to Lessor, the Fleet National Bank Collateral Agent or the
Beneficiaries) to pay taxes, if any, imposed on it or with respect to, the Fleet
National Bank Liquid Collateral.

                7.8     ENTIRE AGREEMENT

                This Agreement, and all instruments and other documents
required to be executed and delivered in connection herewith, represents the
entire agreement of the parties hereto and supercedes all prior agreements and
understandings of the parties with respect to the subject matter covered hereby.

                                   ARTICLE 8

                                    PARTIES

                No Person dealing with the Fleet National Bank Collateral
Agent or any Beneficiary is bound to inquire whether an Enforcement Event shall
have occurred or whether the power that the Fleet National Bank Collateral Agent
or any Beneficiary is purporting to exercise has become exercisable or whether
any Secured Lessee Obligations or Secured Lessor Obligations remain unpaid or
unperformed or otherwise as to the propriety or regularity of any sale or other
dealing by the Fleet National Bank Collateral Agent or any Beneficiary with any
Fleet National Bank Liquid Collateral and all the protections to purchasers
conferred by Applicable Law shall apply to such Persons dealing with the Fleet
National Bank Collateral Agent or any Beneficiary. The receipt by the Fleet
National Bank Collateral Agent or any

                                       16
<PAGE>
                                 FLEET NATIONAL BANK LIQUID COLLATERAL AGREEMENT

Beneficiary of the purchase moneys shall effectively discharge the purchaser who
shall not be concerned with the manner of application thereof.

                                    ARTICLE 9

                                    ELECTION

                So long as Section 6.1(y)(i) of the Participation Agreement does
not require Lessee to secure its Secured Lessee Obligations on the basis of
Properly Margined Liquid Collateral, Lessee shall have the right, upon at least
five Business Days written notice to the Fleet National Bank Collateral Agent
and each of the Participants, to secure its Secured Lessee Obligations on the
basis of either Properly Margined Liquid Collateral or Non-Properly Margined
Liquid Collateral, such change to become effective on the next succeeding
Scheduled Payment Date following such five day notice period.

                            [Signature Pages Follow]

                                       17
<PAGE>
                                 FLEET NATIONAL BANK LIQUID COLLATERAL AGREEMENT

        IN WITNESS WHEREOF the parties hereto have caused this LIQUID
COLLATERAL AGREEMENT to be fully executed as of the day and year first above
written.

                                 HUMAN GENOME SCIENCES, INC.

                                 By:  /s/ STEVEN C. MAYER
                                      -----------------------------
                                      Name:  Steven C. Mayer
                                      Title: Senior Vice President and CFO

                                      S-1
<PAGE>
                                 FLEET NATIONAL BANK LIQUID COLLATERAL AGREEMENT

                                 GENOME STATUTORY TRUST 2001A

                                   By:  Wells Fargo Bank Northwest, N.A., not in
                                   its individual capacity but solely as Trustee

                                 By:  /s/ C. SCOTT NIELSON
                                      -----------------------------
                                      Name:  C. Scott Nielson
                                      Title: Vice President

                                      S-2
<PAGE>
                                 FLEET NATIONAL BANK LIQUID COLLATERAL AGREEMENT

                                 FLEET NATIONAL BANK, as Fleet National
                                 Bank Collateral Agent

                                 By:  /s/ STEVEN CRISCIONE
                                      -----------------------------
                                      Name:  Steven Criscione
                                      Title: Vice President

                                      S-3
<PAGE>
                                 FLEET NATIONAL BANK LIQUID COLLATERAL AGREEMENT

                                 BENEFICIARIES:

                                 FLEET NATIONAL BANK, as a Liquidity
                                 Provider

                                 By:  /s/ STEVEN CRISCIONE
                                      -----------------------------
                                      Name:  Steven Criscione
                                      Title: Vice President

                                      S-4
<PAGE>
                                 FLEET NATIONAL BANK LIQUID COLLATERAL AGREEMENT

                                 FIRST UNION NATIONAL BANK, as a Liquidity
                                 Provider

                                 By:  /s/ BARBARA K. ANGEL
                                      -----------------------------
                                      Name:  Barbara K. Angel
                                      Title: Vice President

                                      S-5
<PAGE>
                                 FLEET NATIONAL BANK LIQUID COLLATERAL AGREEMENT

                                 BANCBOSTON LEASING INVESTMENTS INC.,
                                 as an Investor

                                 By:  /s/ STEVEN CRISCIONE
                                      -----------------------------
                                      Name:  Steven Criscione
                                      Title: Vice President

                                      S-6
<PAGE>
                                 FLEET NATIONAL BANK LIQUID COLLATERAL AGREEMENT

                                 FIRST UNION NATIONAL BANK, as an Investor

                                 By:  /s/ BARBARA K. ANGEL
                                      -----------------------------
                                      Name:  Barbara Kaufmann Angel
                                      Title: Vice President

                                      S-7
<PAGE>
                                 FLEET NATIONAL BANK LIQUID COLLATERAL AGREEMENT

                                 EAGLEFUNDING CAPITAL CORPORATION, as Conduit

                                 By:  /s/ THOMAS M. CALHOUN
                                      -----------------------------
                                      Name:  Thomas M. Calhoun
                                      Title: Director, its
                                             attorney-in-fact

                                      S-8
<PAGE>
                                 FLEET NATIONAL BANK LIQUID COLLATERAL AGREEMENT

                                 FLEET NATIONAL BANK, as Fleet National
                                 Bank Collateral Agent

                                 By:  /s/ STEVEN CRISCIONE
                                      -----------------------------
                                      Name:  Steven Criscione
                                      Title: Vice President

                                      S-9
<PAGE>
                                 FLEET NATIONAL BANK LIQUID COLLATERAL AGREEMENT

                                 FIRST UNION NATIONAL BANK, as First Union
                                 Collateral Agent

                                 By:  /s/ BARBARA K. ANGEL
                                      -----------------------------
                                      Name:  Barbara Kaufmann Angel
                                      Title: Vice President

                                      S-10
<PAGE>
                                 FLEET NATIONAL BANK LIQUID COLLATERAL AGREEMENT

                                 FLEET NATIONAL BANK, as Administrative Agent

                                 By:  /s/ STEVEN CRISCIONE
                                      -----------------------------
                                      Name:  Steven Criscione
                                      Title: Vice President

                                      S-11
<PAGE>
                                 FLEET NATIONAL BANK LIQUID COLLATERAL AGREEMENT

                                                                      SCHEDULE I

                                  Beneficiaries

         1.       Fleet National Bank, as a Liquidity Provider

         2.       First Union National Bank, as a Liquidity Provider

         3.       BancBoston Leasing Investments, Inc., as an Investor

         4.       First Union National Bank, as an Investor

         5.       EagleFunding Capital Corporation, as Conduit

         6.       Fleet National Bank, as Fleet National Bank Collateral Agent

         7.       First Union National Bank, as First Union Collateral Agent

         8.       Fleet National Bank, as Administrative Agent

<PAGE>
                                 FLEET NATIONAL BANK LIQUID COLLATERAL AGREEMENT

                                    EXHIBIT A
                             TO FLEET NATIONAL BANK
                      LIQUID COLLATERAL SECURITY AGREEMENT
                        Description of Pledged Securities

              Designation by Name, Series, Amount and Maturity Date

<TABLE>
<CAPTION>
                                                                             Amount
Name                                               Series                 (At Maturity)          Maturity Date
----                                               ------                 -------------          -------------
<S>                                                <C>                    <C>                   <C>

</TABLE>

                                      Ex.A
<PAGE>
                                 FLEET NATIONAL BANK LIQUID COLLATERAL AGREEMENT

                                    EXHIBIT B

                           Form of Enforcement Notice

 Name and Address of Administrative Agent and Fleet National Bank Custodian

Re:      ENFORCEMENT NOTICE
         Securities Account No. 0006529470 (the "Account (Fleet National Bank)")
         of HUMAN GENOME SCIENCES, INC., as Pledgor (the "Pledgor"), pledged to
         and subject to a first priority security interest in favor of FLEET
         NATIONAL BANK, as Fleet National Bank Collateral Agent (the "Fleet
         National Bank Collateral Agent"), pursuant to the Fleet National Bank
         Liquid Collateral Agreement, dated as of November 7, 2001, among
         Lessee, Lessor, the Fleet National Bank Collateral Agent and the
         Beneficiaries set forth on Schedule I thereto (the "Agreement")
         (capitalized terms used but not otherwise defined herein have the
         respective meanings specified, whether or not by reference, in the
         Agreement)

Ladies and Gentlemen:

                  We hereby demand pursuant to Section 3 of the Custody
Agreement that you take the following action with respect to the Fleet National
Bank Liquid Collateral:

                  [instructions to be provided by Fleet National
                   Bank Collateral Agent]

                                 Very truly yours,

                                 FLEET NATIONAL BANK, as Fleet National
                                 Bank Collateral Agent

                                 By:
                                      -----------------------------
                                          Title:
                                          Date:

                                      Ex.B

<PAGE>

                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                                              PAGE
<S>               <C>                                                                                          <C>
ARTICLE 1         DEFINITIONS, INTERPRETATION

         1.1      Certain Definitions............................................................................2

ARTICLE 2         GRANTING OF SECURITY

         2.1      Granting of Security Interests.................................................................4
         2.2      Remedies.......................................................................................8
         2.3      Pledgors Remain Liable.........................................................................9
         2.4      Instructions Regarding the Account (Fleet National Bank) ......................................9
         2.5      Additional Fleet National Bank Liquid Collateral...............................................9

ARTICLE 3         COVENANTS OF LESSEE

         3.1      No Set-off....................................................................................10
         3.2      Further Transfers.............................................................................11

ARTICLE 4         COVENANTS OF LESSOR AND LESSEE

         4.1      No Set-off....................................................................................11
         4.2      Further Transfers.............................................................................11

ARTICLE 5         REMEDIES

         5.1      Remedies Upon Enforcement Event ..............................................................12
         5.2      Powers of Attorney............................................................................13

ARTICLE 6         RELEASE OF SECURITY INTEREST

         6.1      ..............................................................................................15
         6.2      ..............................................................................................15
         6.3      ..............................................................................................15

ARTICLE 7         MISCELLANEOUS

         7.1      Notices.......................................................................................15
         7.2      Counterparts..................................................................................15
         7.3      Continuing Security...........................................................................16
         7.4      Amendments....................................................................................16
         7.5      Severability..................................................................................16
         7.6      Governing Law.................................................................................17
         7.7      Owner.........................................................................................17
         7.8      Entire Agreement..............................................................................17

ARTICLE 8         PARTIES

ARTICLE 9         ELECTION

</TABLE>

                                      -i-
<PAGE>
                               TABLE OF CONTENTS

                                  (continued)

                                                                            PAGE

EXHIBIT A - DESCRIPTION OF SECURITIES

EXHIBIT B - FORM OF ENFORCEMENT NOTICE

                                      -ii-<PAGE>
                                                                  EXHIBIT 10.22

                               LEASE AGREEMENT

                                   BETWEEN

              WELLS FARGO BANK NORTHWEST, NATIONAL ASSOCIATION,
         not in its individual capacity, but solely as Owner Trustee
                      under that certain Trust Agreement
                   dated as of October 25, 2001, as Lessor

                                     AND

                    HUMAN GENOME SCIENCES, INC., as Lessee

                         Dated as of October 25, 2001

<PAGE>

                              TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                                         Page
<S>                                                                                                     <C>
1.    Demise of Property...................................................................................1
2.    Certain Definitions..................................................................................1
3.    Title...............................................................................................12
4.    Use of Property.....................................................................................13
5.    Term................................................................................................13
6.    Rent................................................................................................13
7.    Net Lease; Non-Terminability........................................................................15
8.    Payment of Impositions; Compliance with Law, Restrictive Covenants and Operative Documents..........16
9.    Liens...............................................................................................16
10.   [INTENTIONALLY RESERVED]............................................................................17
11.   Lessee's Equipment; Building Equipment..............................................................17
12.   Alterations.........................................................................................18
13.   Construction of Additional Improvements.............................................................19
14.   Insurance...........................................................................................22
15.   Assignment and Subletting...........................................................................22
16.   Permitted Contests..................................................................................24
17.   Default Provisions..................................................................................24
18.   Additional Rights of Lessor.........................................................................31
19.   Sale, Return or Purchase of Property................................................................32
20.   Inspection..........................................................................................37
21.   Notices, Demands and Other Instruments..............................................................37
22.   Estoppel Certificates...............................................................................37
23.   No Merger...........................................................................................38
24.   Representations and Warranties of Lessee............................................................38
25.   Affirmative Covenants of Lessee.....................................................................40
26.   Negative Covenants of Lessee........................................................................42
27.   [INTENTIONALLY RESERVED.]...........................................................................43
28.   Separability........................................................................................43
29.   Subordination.......................................................................................43
30.   Binding Effect......................................................................................44
31.   Headings............................................................................................44
32.   Environmental Matters...............................................................................44
33.   Quiet Enjoyment.....................................................................................48
34.   [INTENTIONALLY RESERVED.]...........................................................................48
35.   Nature of Transaction...............................................................................48
36.   Grant of Lien and Future Assurances.................................................................49
37.   Miscellaneous.......................................................................................53
38.   Partial Release of Land.............................................................................54
</TABLE>

                                      i

<PAGE>

LIST OF EXHIBITS
EXHIBIT A.........         Description of Land
EXHIBIT B.........         Intentionally Omitted
EXHIBIT C.........         Schedule of Basic Rent Payments
EXHIBIT D.........         Notice and Payment Information
EXHIBIT E.........         Security Agreement and Assignment

                                      ii

<PAGE>

                               LEASE AGREEMENT

         THIS LEASE AGREEMENT (this "Lease") is made as of October 25, 2001,
by and between WELLS FARGO BANK NORTHWEST, NATIONAL ASSOCIATION, not in its
individual capacity, but solely as Owner Trustee under that certain Trust
Agreement dated as of October 25, 2001 ("Lessor") and HUMAN GENOME SCIENCES,
INC., a Delaware corporation ("Lessee").

                                   RECITALS

         A.       Lessor, pursuant to the Trust Agreement, has appointed Val
T. Orton, not in his individual capacity, but solely as Maryland trustee, to
serve as Maryland trustee (the "Maryland Trustee") for that portion of the
Owner Trust Estate located from time to time in the State of Maryland.

         B.       Lessor, at the request of Lessee, has caused the Maryland
Trustee to acquire from Issuer (as hereinafter defined) a leasehold interest
in certain real property located in Montgomery County, Maryland, consisting of
a parcel of land containing 18.1376 acres and more particularly described on
Exhibit A attached hereto and made a part hereof (the "Land") and all the
buildings, structures and other improvements located thereon (collectively,
the "Improvements").

         C.       Lessor now desires, acting through the Maryland Trustee, to
sublease the Property to Lessee and Lessee desires to sublease the Property
from Lessor, acting through the Maryland Trustee, subject to the terms and
conditions set forth herein. To evidence the foregoing, the Maryland Trustee
and Lessee shall enter into a Lease Supplement with respect to the Property
simultaneously with the execution hereof by Lessor and Lessee.

                                  AGREEMENTS

         NOW, THEREFORE, in consideration of the mutual promises and covenants
contained herein, and other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, Lessor and Lessee hereby
covenant and agree as follows:

         1. Demise of Property. In consideration of the rents and covenants
herein stipulated to be paid and performed, Lessor, acting through the
Maryland Trustee, hereby demises and sublets to Lessee, and Lessee hereby
demises and sublets from Lessor, acting through the Maryland Trustee, the
Property.

         2. Certain Definitions. The following terms shall have the
definitions provided below. Unless specifically provided otherwise, all
accounting terms have the definitions given them in accordance with GAAP
(hereinafter defined) as applied to the applicable Person on a consistent
basis by its accountants in the preparation of its previous annual financial
statements.

<PAGE>

         Act of Bankruptcy means with respect to any Person, the filing of a
petition in bankruptcy under the Bankruptcy Code, or the commencement of a
proceeding under any other applicable law concerning insolvency,
reorganization or bankruptcy, by or against such Person as debtor.

         Accumulated Funding Deficiency means an "accumulated funding
deficiency" as defined in Section 302 of ERISA or Section 412(a) of the Code.

         Additional Improvements means the approximately 45,000 square foot
building to be constructed on the Land in accordance with Plans to be approved
by Lessor, Agent and Lessee.

         Additional Rent means Additional Rent as defined in Paragraph 6(c).

         Affiliate means: (a) any Person in which Lessee legally or
beneficially owns or holds, directly or indirectly, any capital stock or other
equity interest; (b) any Person that is a partnership in which Lessee is a
partner, or a joint venturer in which Lessee is a joint venturer or a limited
liability company of which Lessee is a managing member; (c) any Person that is
a director, officer, employee, stockholder (legally or beneficially) or other
affiliate of any of the foregoing or of Lessee; and (d) any Person that
directly or indirectly controls, is under the control of, or is under common
control with, Lessee, including, without limitation, any Person that directly
or indirectly has the right or power to direct the management or policies of
Lessee and any Person whose management or policies Lessee directly or
indirectly has the right or power to direct.

         Agent means the Bank, acting not in its individual capacity, but
solely as agent for the Participants.

         Alterations means all changes, additions, improvements or repairs to,
all alterations, reconstructions, renewals or removals of and all
substitutions or replacements for any of the Improvements (including the
Additional Improvements following completion of construction thereof), both
interior and exterior, structural and non-structural, and ordinary and
extraordinary.

         Appurtenances means (i) all agreements, easements, rights of way or
use, rights of ingress or egress, privileges, appurtenances, tenements,
hereditaments and other rights and benefits at any time belonging or
pertaining to the Land or the Property, including, without limitation, the use
of any streets, ways, alleys, vaults, strips of land adjoining, abutting,
adjacent or contiguous to the Land and (ii) all permits, licenses and rights,
whether or not of record, appurtenant to the Land.

         Assessment has the meaning set forth in Paragraph 32(e).

         Bankruptcy Code means Title 11 of the United States Code, as amended,
and all rules and regulations promulgated pursuant thereto.

         Bank means Allfirst Bank, a Maryland banking corporation, its
successors and assigns.

         Basic Rent means Basic Rent as defined in Paragraph 6(a).

                                      2

<PAGE>

         Beneficiary means the Agent, as Beneficiary under the Deed of Trust.

         Bond Documents has the meaning given to such term in the Indenture.

         Bonds means, the $73,000,000.00 Taxable Rate Demand Revenue Bonds
(Human Genome Sciences, Inc. Facility), Series 2001A, being issued by Issuer
to refinance a portion of the costs of the acquisition of the Property and
finance a portion of the costs attributable to the construction of the
Additional Improvements.

         Break Costs means an amount equal to the amount, if any, required to
compensate any Certificate Holder or any Credit Facility Provider for any
additional losses (including, without limitation, any loss, cost or expense
incurred by reason of the liquidation or reemployment of deposits or funds
acquired by any Certificate Holder or any Credit Facility Provider to fund its
obligations under the Operative Documents) it may incur as a result of (a)
Lessee's payment of Basic Rent other than on a Payment Date or (b) as a result
of any conversion of the LIBO Rate other than on the last day of an Interest
Period pursuant to and in accordance with the Operative Documents. A statement
as to the amount thereof, prepared in good faith and in reasonable detail and
submitted by any Certificate Holder or any Credit Facility Provider, as the
case may be, to Lessee, shall be presumed correct absent demonstrable error.

         Building Equipment means all fixtures, furnishings, fittings and all
appurtenances and additions thereto and substitutions or replacements thereof
(together with, in each case, attachments, components, parts and accessories)
affixed or attached to, or to be affixed or attached to, the Property,
together with all fixtures, furnishings, fittings, equipment, machinery and
other personal property listed on Schedule 1 attached hereto or the
acquisition of which is funded with either the proceeds of the Bonds or the
MEDCO Note.

         Business Day means any day other than a day on which either (a) banks
located in any of the cities in which the Principal Office of the Trustee, the
Credit Facility Providers, the Paying Agent and the Remarketing Agent is
located are required or authorized by law or executive order to close for
business, or (b) the New York Stock Exchange is closed; provided, however,
that relative to any determination of the LIBO Rate, a Business Day shall mean
any day which is a Business Day under clause (a) or (b) and is also a day on
which commercial banks are open for domestic and international business,
including dealings in Dollars.

         Certificates means those certain certificates issued by Lessor, as
Owner Trustee under the Trust Agreement, in favor of the Bank or any
subsequent holder thereof in the aggregate principal amount of $3,000,000.00.

         Certificate Holder means, initially, the Bank and any subsequent
holder of the Certificates.

         Change in Control means the occurrence of any of the following: (a)
the sale, lease, transfer, conveyance or other disposition (other than by way
of merger or consolidation) in one or a series of related transactions, of all
or substantially all of the assets of Lessee and its Subsidiaries taken as a
whole to any "person" (as such term is used in Section 13(d)(3) of the
Exchange Act), (b) the adoption of a plan relating to the liquidation or
dissolution of Lessee, or (c) the consummation of any transaction (including,
without limitation, any merger or

                                      3

<PAGE>

consolidation) the result of which is that any "person" (as defined above),
becomes the "beneficial owner" (as such term is defined in Rule 13d-3 and Rule
13d-5 under the Exchange Act), directly or indirectly, of more than 51% of the
voting stock of Lessee.

         Code means the Internal Revenue Code of 1986, or any applicable
predecessor or successor statutory provision. Each reference to a section of
the Code herein shall be deemed to include the final and temporary United
States Treasury Regulations in effect from time to time with respect thereto.

         Collateral has the meaning given to such term in Collateral Pledge
Agreement.

         Collateral Pledge Agreement means the Cash Collateral Pledge
Agreement dated as of October 25, 2001, between and among Lessee, as Pledgor;
the Agent, as Pledgee; and Trustee, as Collateral Agent, together with all
amendments thereto and modifications thereof.

         Commencement Date means October 25, 2001.

         Commonly Controlled Entity means any trade or business (whether or
not incorporated) which is a member of a "controlled group of corporations"
(as such phrase is used and defined in Section 414(b) of the Code) or which is
under "common control" (as such phrase is used and defined in Section 414(c)
of the Code), and of which Lessee is a part.

         Construction Agent means the Construction Agent as defined in
Paragraph 13(a).

         Construction Commencement Date means the Construction Commencement
Date as defined in Paragraph 13(c).

         Construction Consultant means the Construction Consultant as defined
in Paragraph 13(i).

         Construction Consultant Report means the Construction Consultant
Report as defined in Paragraph 13(i).

         Construction Documents means the Construction Documents as defined in
Paragraph 13(d).

         Construction Period means the period commencing on the Commencement
Date and terminating on the Substantial Completion Date.

         Credit Facilities has the meaning given to such term in the
Indenture.  The initial Credit Facility is the Letter of Credit.

         Credit Facility Agreements has the meaning given to such term in the
Indenture. The initial Credit Facility Agreement is the Letter of Credit
Agreement.

         Credit Facility Documents has the meaning given to such term in the
Indenture. The initial Credit Facility Documents are the Letter of Credit
Documents.

                                      4

<PAGE>

         Credit Facility Providers has the meaning given to such term in the
Indenture. The initial Credit Facility Provider is the Bank.

         Deed of Trust means the Deed of Trust, Assignment of Leases, Security
Agreement and Fixture Filing dated as of October 25, 2001, encumbering all
right, title and interest of Issuer, the Lessor, the Maryland Trustee and
Lessee in and to the Property, from Issuer, the Lessor, the Maryland Trustee
and Lessee to certain individual trustees for the benefit of the Beneficiary,
together with all amendments thereto and modifications thereof.

         Deed of Trust Trustee has the meaning set forth in Paragraph 36(e).

         Default means any Event of Default or any condition, occurrence or
event which, after notice or lapse of time or both, would constitute an Event
of Default.

         Default Rate means the Default Rate as defined in Paragraph 6(d).

         Dollar means currency of the United States of America.

         Downgrade has the meaning given to such term in the Letter of Credit
Agreement.

         Encumbrances means any mortgage, pledge, lien, security interest,
charge or other encumbrance.

         Environmental Audit means the Environmental Audit as defined in
Paragraph 32(d).

         ERISA means the Employee Retirement Income Security Act of 1974, as
amended, and all Laws promulgated pursuant thereto or in connection therewith.

         Event of Default means an Event of Default as defined in Paragraph
17.

         Exchange Act means the Securities Exchange Act of 1934, as amended.

         Expiration Date means the date which is one day immediately preceding
the seventh anniversary of the Commencement Date.

         Facility Fund has the meaning given to such term in the Indenture.

         Fair Market Value means with respect to the Property or any portion
thereof, as of the date of the determination, the fair market value (which in
any event shall not be less than zero) as determined by an independent
appraiser chosen by Lessor (with the approval of the Agent) and reasonably
acceptable to Lessee that would be obtained in an arm's-length transaction
between an informed and willing buyer (other than a buyer currently in
possession) and an informed and willing seller, under no compulsion to buy or
sell, and neither of which is related to Lessor, the Credit Facility Providers
or Lessee or any Affiliate, for the purchase of the Property or such portion
thereof, as applicable. Such fair market value shall be calculated assuming
that the Property is in the condition and repair required to be maintained by
the terms of this Lease.

         Final Completion Date has the meaning given to such term in Paragraph
13(f).

                                      5

<PAGE>

         Final Rent Payment Date has the meaning given to such term in
Paragraph 17(b).

         GAAP means generally accepted accounting principles in the United
States of America in effect from time to time, consistently applied. In the
event of a change in GAAP affecting the covenants contained in Paragraphs 25
or 26 of this Lease or definitions contained in Paragraph 2 of this Lease
relating to such covenants, such covenants and definitions shall continue to
be applied as though such change in GAAP had not occurred unless and until
Lessor, Agent and Lessee shall agree in writing to amend or adjust such
covenants or definitions as deemed necessary as a result of such change in
GAAP.

         Governmental Authority means any nation or government, any state or
other political subdivision thereof, any central bank (or similar monetary or
regulatory authority) thereof, any entity exercising executive, legislative,
judicial, regulatory or administrative functions of or pertaining to
government, and any corporation or other entity owned or controlled, through
stock or capital ownership or otherwise, by any of the foregoing.

         Guarantee means that certain Guarantee of even date herewith executed
by the Lessee in favor of the Beneficiary, for the benefit of the
Participants.

         Guarantor means Human Genome Sciences, Inc., a Delaware corporation.

         Head Lease means the Lease Agreement dated as of October 25, 2001, by
and between Issuer, as head lessor, and the Maryland Trustee, as head lessee,
together with all amendments thereto and modifications thereof, pursuant to
which Issuer leased to the Maryland Trustee, and the Maryland Trustee leased
from Issuer, the Property.

         Head Lessor's Fee has the meaning given to such term in the Head
Lease.

         Hedge means any interest rate swap or similar hedge arrangement in
existence at any time or from time to time between Issuer and any Hedge
Counterparty.

         Hedge Agreement means any agreement between Issuer and any Hedge
Counterparty in existence at any time or from time to time, executed in
connection with any Hedge, including (without limitation) the Swap Agreement
(as defined in the Letter of Credit Agreement), together with all amendments
thereto and modifications thereof.

         Hedge Counterparty means any Person, in its capacity as counterparty
to any Hedge Agreement, with which Issuer has entered into any Hedge or may
hereafter at any time or from time to time enter into any Hedge, including
(without limitation) the Bank and any other Credit Facility Provider.

         Hedge Documents means, collectively, any Hedge Agreement and all
other documents in existence at any time or from time to time, executed and
delivered to evidence, secure, or in connection with, any Hedge.

         Holder Yield has the meaning given to such term in the Trust
Agreement.

                                      6

<PAGE>

         Impositions means any and all liabilities, losses, expenses, costs,
charges and liens of any kind whatsoever for fees, taxes, levies, imposts,
duties, charges or assessments or withholdings ("Taxes") including but not
limited to (i) real and personal property taxes, including without limitation
personal property taxes on any property covered by the Operative Documents
that is classified by any Governmental Authority as personal property, and
real estate or ad valorem taxes in the nature of property taxes; (ii) sales
taxes, use taxes and other similar taxes (including rent taxes and intangibles
taxes); (iii) excise taxes; (iv) real estate transfer taxes, conveyance taxes,
stamp taxes and documentary recording taxes and fees; (v) taxes that are or
are in the nature of franchise, gross or net income, gross or net receipts,
value added, privilege and doing business taxes; (vi) assessments on any
Property or part thereof, including without limitation all assessments for
public improvements or benefits, whether or not such improvements are
commenced or completed within the term of the Facility Lease; (viii) water and
sewer rents, rates and charges, license, permit, inspection, registration and
other authorization fees and other charges or costs of any nature whatsoever
and (ix) taxes, liens, assessments or charges asserted, imposed or assessed by
the PBGC or any governmental authority succeeding to or performing functions
similar to, the PBGC, in each case whether general or special, ordinary or
extraordinary, foreseen or unforeseen, of every character (including all
interest, additions to tax and penalties thereon), which at any time during or
in respect of the term hereof may be levied, assessed, confirmed or imposed by
any Governmental Authority upon or with respect to, or be a lien upon (a) any
Participant, the Lessee, the Property or any part thereof or interest therein,
the Collateral or any portion thereof, or the Lessee or any sublessee or user
of the Property or any part thereof or interest therein; (b) the leasing,
financing, refinancing, demolition, construction, installation, substitution,
subleasing, acquisition, acceptance, inspection, assignment, control,
condition, servicing, maintenance, repair, ownership, possession, sale,
purchase, rental, lease, activity conducted on or in, delivery, insuring, use,
operation, improvement, transfer, return or disposition of the Property or any
part thereof or interest therein; (c) the MEDCO Note or other indebtedness
with respect to the Property or the Collateral or any part thereof or interest
therein or transfer thereof; all rent payable under the Head Lease and/or the
Facility Lease or the receipts or earnings arising from or received with
respect to the Property or the Collateral or any part thereof or interest
therein or any applications or dispositions thereof, (d) any other amount paid
or payable pursuant to the MEDCO Note or any of the other Operative Documents,
(e) all or any of the Operative Documents, any other documents contemplated
thereby, any amendments and supplements thereto, and (f) otherwise with
respect to or in connection with the transactions contemplated by the
Operative Documents or the performance or enforcement thereof.

         Improvements means the buildings, structures and other improvements
located from time to time on the Land, including the Additional Improvements
following completion of construction thereof in accordance with the terms of
this Lease.

         Indenture means the Trust Indenture dated as of October 25, 2001,
between Issuer and the Trustee, together with all amendments thereto and
modifications thereof.

         Inspecting Parties has the meaning set forth in Paragraph 20.

         Insurance Requirements means all terms and conditions of any
insurance policy required by the Deed of Trust to be maintained by Lessee and
all requirements of the insurers thereunder applicable to Lessor, the Credit
Facility Providers, Issuer, Lessee or the Property or to the use,

                                      7

<PAGE>

manner of use, occupancy, possession, operation, maintenance, alteration or
repair of the Property.

         Interim Synthetic Lease means that certain letter agreement dated as
of May 1, 2001, by and among the Bank, the Issuer, the Lessor and the Lessee
and all other documents executed in connection therewith, together with all
amendments thereto and modifications thereof.

         Invitrogen means Invitrogen Corporation, its successors and assigns.

         Invitrogen Sublease means the Invitrogen Sublease as defined in
Paragraph 15(a).

         Issuer means the Maryland Economic Development Corporation, a body
politic and corporate and a public instrumentality of the State of Maryland.

         Land means that parcel of land described in Exhibit A attached
hereto.

         Law means all applicable laws (including Environmental Laws), rules,
regulations (including temporary and final income tax regulations), statutes,
treaties, codes, ordinances, permits, certificates, orders and licenses of and
interpretations by, any Governmental Authority, and applicable judgments,
decrees, injunctions, writs, orders or like action of any court, arbitrator or
other administrative, judicial or quasi-judicial tribunal or agency of
competent jurisdiction (including those pertaining to health, safety or the
environment (including, without limitation, wetlands) and those pertaining to
the construction, use or occupancy of the Property and the foreclosure of the
Deed of Trust with respect thereto).

         Lease Balance means, with respect to the Property, as of any date of
determination, an amount equal to the aggregate sum of (i) the outstanding
principal amount of the Bonds, including all accrued and unpaid interest
thereon, (ii) the outstanding principal amount of the Certificates, including
all accrued and unpaid Yield thereon, (iii) amounts due to the Hedge
Counterparty under the Hedge Documents and the Collateral Pledge Agreement,
and (iv) any other amounts due and owing under the Operative Documents,
including without limitation, all amounts owed to the Credit Facility
Providers under the Credit Facility Documents (provided, however, that if the
Lessee exercises its option to purchase the Property on the Expiration Date,
all amounts owed under the Credit Facility Documents through and including the
expiration of the Credit Facility Documents shall also be included within this
calculation).

         Lease Supplement means that certain Montgomery County, Maryland Lease
Supplement, Short Form/ Memorandum of Lease and Remedies dated as of October
25, 2001, between and among the Maryland Trustee, Lessee and Agent, together
with all amendments thereto and modifications thereof.

         Legal Requirements means all laws, statutes, codes, acts, ordinances,
orders, judgments, decrees, injunctions, rules, regulations, permits,
licenses, authorizations, directions, requirements and agreements with all
governments, departments, commissions, boards, courts, authorities, agencies,
officials and officers, foreseen or unforeseen, ordinary or extraordinary,
which now or at any time hereafter may be applicable to the use, occupancy,
possession, maintenance, alteration, repair or reconstruction of any of the
Property.

                                      8

<PAGE>

         Lessee Collateral means all of Lessee's right, title and interest in
and to (i) the Property, (ii) contracts, contract rights and general
intangibles relating to the Property and (iii) proceeds of any of the
foregoing.

         Lessee's Equipment means Lessee's machinery, apparatus, furnishings
and other equipment that is (i) not paid for, directly or indirectly, with
proceeds from the Bonds or the Certificate, (ii) not included in any
requisition or in any disbursement from the Facility Fund or any advance under
the Certificate, (iii) not a fixture or otherwise affixed to any part of the
Property, and (iv) not in replacement for any of the property described in
clauses (I) through (iii) above or for any of the other Building Equipment.

         Lessor means Wells Fargo Bank Northwest, National Association, not in
its individual capacity, but solely as Owner Trustee under that certain Trust
Agreement dated as of October 25, 2001.

         Lessor Liens means any mortgage, pledge, lien, security interest,
charge or other encumbrance (a) which results from any act or omission of, or
any claim against, Lessor unrelated to the transactions contemplated by the
Operative Documents or from Lessor's failure to perform as required under the
Operative Documents or (b) which result from any Impositions owed by Lessor,
except any Imposition for which Lessee is obligated to indemnify (including,
without limitation, in the foregoing exception, any Impositions on the
Property or assessed in connection with any construction or development by
Lessee or Construction Agent).

         Letter of Credit means that certain Letter of Credit to be issued by
the Bank in the initial stated amount of $74,080,000.00 for the account of
Issuer as security for the Bonds, as the same may from time to time be
modified, amended, supplemented, renewed or replaced.

         Letter of Credit Agreement means that certain Letter of Credit
Agreement between the Bank and Issuer dated as of October 25, 2001, as the
same may from time to time be modified, amended, supplemented, renewed or
replaced.

         Letter of Credit Documents has the meaning given to such term in the
Letter of Credit Agreement.

         LIBO Rate means with respect to any thirty (30) day period, the
applicable London interbank offered rate for deposits in U.S. dollars
appearing on Telerate Page 3750 as of 11:00 a.m. (London time) two (2)
Business Days prior to the first day of such thirty (30) day period, and
having a maturity approximately equal to thirty (30) days, or if no London
interbank offered rate of such maturity then appears on Telerate Page 3750,
then the rate equal to the London interbank offered rate for deposits in U.S.
dollars maturing immediately before or immediately after such maturity,
whichever is higher, as determined by Allfirst Bank from Telerate Page 3750,
or if Telerate Page 3750 is not available, the applicable LIBO Rate for the
relevant thirty (30) day period shall be the rate determined by Allfirst Bank
from the Reuters Screen LIBO Page or, if such rate is also unavailable on such
service, then on any other interest rate reporting service of recognized
standing designated in writing by the Allfirst Bank to Lessee and the
Certificate Holder, in any such case rounded, if necessary, to the next higher
1/100 of 1.0%, if the rate is not such a multiple.

                                      9

<PAGE>

         Liquidity Covenant means the covenant described in Paragraph 25(g).

         Maryland Trustee means Val T. Orton, not in his individual capacity,
but solely as Maryland Trustee for that portion of the Owner Trust Estate
located in the State of Maryland.

         MEDCO Note means that certain promissory note dated as of October 25,
2001 in the original principal amount of $3,000,000.00 made by Issuer in favor
of Lessor, together with all amendments thereto and modifications thereof.

         Mortgaged Property has the meaning set forth in Paragraph 36(e).

         Multiemployer Plan means a multiemployer plan (as defined in Section
4001(a)(3) of ERISA) to which Lessee, or any Commonly Controlled Entity, as
appropriate, has or had an obligation to contribute.

         Operative Documents means this Lease, the Lease Supplement, the Head
Lease, the Bond Documents, the Credit Facility Agreements, the Credit Facility
Documents, the Collateral Pledge Agreement, the Letter of Credit, the Letter
of Credit Agreement, the Letter of Credit Documents, the MEDCO Note, the
Certificates, the Hedge Documents, if applicable, the Guarantee and the Deed
of Trust.

         Owner Trust Estate has the meaning given to such term in the Trust
Agreement.

         Owner Trustee means Wells Fargo Bank Northwest, National Association,
not in its individual capacity, but solely as Owner Trustee under the Trust
Agreement.

         Participants means the Credit Facility Providers, the Certificate
Holders and the Hedge Counterparty.

         Paying Agent has the meaning given to such term in the Indenture.

         Payment Date means the first (1st) Business Day of each calendar
month during the Term.

         Permitted Equipment Lien means any encumbrance or other lien upon, or
security interest in, or any equipment lease of, any Lessee's Equipment, or
interest therein, provided that the beneficiary of any such encumbrance, lien
or security interest or the lessor under any equipment lease (i) acknowledges
and agrees that its right to remove any of Lessee's Equipment must be
exercised immediately upon or prior to the expiration or earlier termination
of this Lease (the beneficiary or the lessor, as the case may be,
acknowledging and agreeing that any Lessee's Equipment not so removed
immediately upon or prior to the expiration or earlier termination of this
Lease shall be considered abandoned by Lessee, and may be appropriated, sold,
destroyed or otherwise disposed of by Lessor without first giving notice
thereof and without obligation to account therefor to either Lessee,
beneficiary or lessor as the case may be), (ii) covenants and agrees to repair
(and, if necessary, replace), at its sole cost and expense, any damage to the
Property caused by the removal of Lessee's Equipment, and (iii) acknowledges
and agrees that its encumbrance, lien or security interest or equipment lease
shall not create any lien upon, security interest in or encumbrance upon the
Property.

                                      10

<PAGE>

         Permitted Investments has the meaning given to such term in the
Collateral Pledge Agreement.

         Permitted Use means the Permitted Use as defined in Paragraph 4.

         Person means any natural person, firm, association, corporation,
company, trust, partnership, public body or other entity.

         Personalty has the meaning set forth in Paragraph 36(g).

         Plan means any pension, profit sharing, savings or stock bonus plan
established or maintained by the Lessee or any Commonly Controlled Entity that
is intended to satisfy the qualification requirements under Code Section 401
and is subject to the requirements of ERISA, together with any related trusts.

         Plans means the Plans and Specifications for the Additional
Improvements which shall be approved, in writing by Lessor, Agent and Lessee,
as the same may be modified or amended in accordance with Paragraph 13(g).

         Prohibited Transaction means a "prohibited transaction" as defined in
Section 406 of ERISA or Section 4975 of the Code.

         Property means, collectively, the Land, the Improvements, the
Appurtenances and the Building Equipment, together with Alterations thereto.

         Purchase Option has the meaning given to such term in Paragraph
19(a).

         Release Fee has the meaning given to such term in Paragraph 38.

         Release Parcel has the meaning given to such term in Paragraph 38.

         Remarketing Agent has the meaning given to such term in the
Indenture.

         Remarketing Option has the meaning given to such term in Paragraph
19(f).

         Rent means Basic Rent and Additional Rent.

         Reportable Event means a "reportable event" as defined in Section
4043 of ERISA or the regulations issued thereunder.

         Residual Guaranty Amount means, as of any date of determination, the
product obtained by multiplying (i) the Lease Balance times (ii) 85%.

         Restrictive Covenants means the covenants and restrictions set forth
in the Amended and Restated Declaration of Covenants and Easements made the
9th day of March, 1990, by and between Montgomery County, Maryland and Redgate
III Limited Partnership, and recorded among the Land Records of Montgomery
County, Maryland, in Liber 9332 at folio 591.

         Subject Contracts has the meaning set forth in Paragraph 36(e).

                                      11

<PAGE>

         Subject Leases has the meaning set forth in Paragraph 36(e).

         Subsidiary or Subsidiaries means, with respect to any Person
(including Lessee), any present or future Person at least a majority of whose
outstanding Voting Stock shall at the time be owned by such Person (including
Lessee) or by one or more Subsidiaries of such Person, or by such Person
(including Lessee) and one or more Subsidiaries of such Person (including
Lessee).

         Substantial Completion means the date on which the Additional
Improvements are in such condition that Lessee may commence its final fit out
of the Additional Improvements and move in and a Certificate of Occupancy of a
tenantable shell either has been issued or would be issued except for work to
be performed by Lessee.

         Substantial Completion Date has the meaning given to such term in
Paragraph 13(c).

         Term means the Term as defined in Paragraph 5.

         Trust Agreement means that certain Trust Agreement dated as of
October 25, 2001, by and between the Owner Trustee and the Bank, together with
all amendments thereto and modifications thereof.

         Trustee means Allfirst Trust Company National Association, not in its
individual capacity, but solely as Bond Trustee, its successors and assigns.

         Voting Stock means the shares of any class of capital stock of a
Person having ordinary voting power to elect the directors, managers or
trustees thereof (irrespective of whether or not at the time stock of any
class or classes of such Person shall have or might have voting power by
reason of the happening of any contingencies).

         3. Title.

                  (a) The Property is demised and let subject to (i) the Head
Lease, (ii) the Deed of Trust and any Encumbrances executed in connection
therewith and all of the terms and provisions thereof, including but not
limited to the provisions governing disbursement of insurance proceeds and
condemnation awards, (iii) the existing state of the title of the Land as of
the date hereof and any other exceptions or encumbrances of record as of the
date hereof and any other restrictions, exceptions and Encumbrances entered
into subsequent to the date hereof with Lessee's knowledge and written
consent, which consent shall not be unreasonably withheld or delayed provided
Lessee's rights hereunder are not adversely affected in a material manner,
(iv) any state of facts which an accurate survey or physical inspection of the
Property might show, and (v) the condition of the Property, as of the
Commencement Date. So long as no Default or Event of Default exists hereunder,
Lessor covenants and agrees not to amend or modify any of the terms and
conditions of the Head Lease without the prior written consent of Lessee,
which consent shall not be unreasonably withheld, conditioned or delayed.

                  (b) Lessee has made its own investigation as to the existing
state of the title of the Land and has obtained its own survey. Lessee has
also made its own investigation as to the

                                      12

<PAGE>

physical condition of the Property. Based upon the foregoing, Lessee hereby
acknowledges its acceptance of the Property and the suitability of the
Property for the Permitted Use.

                  (c) LESSEE ACKNOWLEDGES THAT, ALTHOUGH LESSOR WILL OWN AND
HOLD TITLE TO OR A LEASEHOLD INTEREST IN THE PROPERTY, LESSOR IS NOT
RESPONSIBLE FOR THE CONDITION OF THE PROPERTY OR ANY ALTERATIONS. NEITHER
LESSOR, AGENT NOR ANY CREDIT FACILITY PROVIDER HAS MADE OR SHALL BE DEEMED TO
HAVE MADE ANY REPRESENTATION OR WARRANTY, EXPRESS OR IMPLIED, OR SHALL BE
DEEMED TO HAVE ANY LIABILITY WHATSOEVER AS TO THE VALUE, MERCHANTABILITY,
TITLE, HABITABILITY, CONDITION, DESIGN, OPERATION, OR FITNESS FOR USE OF THE
PROPERTY (OR ANY PART THEREOF), OR ANY OTHER REPRESENTATION OR WARRANTY
WHATSOEVER, EXPRESS OR IMPLIED, WITH RESPECT TO THE PROPERTY (OR ANY PART
THEREOF), ALL SUCH WARRANTIES BEING HEREBY DISCLAIMED, AND NEITHER LESSOR,
AGENT NOR ANY CREDIT FACILITY PROVIDER SHALL BE LIABLE FOR ANY LATENT, HIDDEN,
OR PATENT DEFECT THEREIN OR THE FAILURE OF THE PROPERTY, OR ANY PART THEREOF,
TO COMPLY WITH LAW.

         4. Use of Property. Lessee shall occupy and use the Property for any
lawful use (the "Permitted Use"), subject to the terms and provisions of any
covenants, easements, conditions or restrictions of record as of the
Commencement Date or hereafter recorded with the written consent of Lessee and
Agent, including but not limited to the Deed of Trust and the Restrictive
Covenants, and for no other purpose. Lessee shall not abandon the Property.
Lessee shall not permit any unlawful occupation, business or trade to be
conducted on the Property or any portion thereof or any use to be made thereof
contrary to applicable Legal Requirements or Insurance Requirements. Lessee
shall not use or occupy or permit the Property or any portion thereof to be
used or occupied, nor do or permit anything to be done in or on the Property
or any portion thereof, in a manner which would or might (i) constitute a
default under the Head Lease or any of the other Operative Documents, (ii)
make void or voidable any insurance then in force with respect to any of the
Property, (iii) make it impossible to obtain fire or other insurance which
Lessee is required to furnish hereunder, (iv) cause structural injury to any
of the Improvements, (v) constitute a public or private nuisance or waste or
(vi) impair the Fair Market Value, utility or remaining useful life of the
Property.

         5. Term. Unless earlier terminated pursuant to the terms hereof, the
term of this Lease (the "Term") shall commence on the Commencement Date and
end on the Expiration Date.

         6. Rent.

                  (a) Beginning with and including the first Payment Date
occurring after the Commencement Date, Lessee shall pay to the Agent, on
behalf of Lessor, by wire transfer of immediately available federal funds
using the wiring instructions set forth in Exhibit D attached hereto or by
such other method of payment as may be mutually agreed upon by Lessor, Lessee
and Agent, basic rent in the amounts set forth in Exhibit C attached hereto,
subject to adjustment as set forth in subparagraph (b) below (such basic rent,
as so adjusted from time to time, is hereinafter referred to as "Basic Rent").
Basic Rent shall be absolutely net to Lessor, so that this

                                      13

<PAGE>

Lease shall yield to Lessor the Basic Rent throughout the Term and shall be
paid without demand or offset, as more particularly provided hereinafter. Each
installment of Basic Rent received by the Agent shall be disbursed by the
Agent in accordance with Article IX of the Deed of Trust.

                  (b) Lessor and Lessee acknowledge and agree that Basic Rent
has been determined based upon a number of factors, which include the amount
of interest payable on the aggregate sum of the outstanding principal amount
of the Bonds from time to time, the yield payable on the aggregate sum of the
outstanding principal amount of Certificates from time to time and any other
amounts and costs payable pursuant to the Operative Documents. Accordingly,
Basic Rent shall be adjusted from time to time by Lessor and Lessee to reflect
(i) any increase in the aggregate sum of the outstanding principal amount of
the Bonds and/or the Certificates, (ii) any redemption of the Bonds prior to
maturity, (iii) any increase or decrease in Basic Rent as a result of the
existence of the Hedge Documents, (iv) the expiration of any Hedge or any
default by any Hedge Counterparty in the performance of its obligations under
any Hedge Documents, and (v) any additional amounts and costs that become due
and owing pursuant to the other Operative Documents.

                  (c) Lessee covenants and agrees to pay and discharge, as
additional rent (the "Additional Rent"), all amounts, liabilities and
obligations (other than Basic Rent) which Lessee assumes or agrees or is
otherwise obligated to pay under this Lease or any other Operative Document
(whether or not designated as Additional Rent) to Agent or any other Person,
including without limitation, the Head Lessor's Fee, any costs otherwise
payable by Issuer under the Hedge Documents, Break Costs, the Residual
Guaranty Amount and any Lease Balance. Each payment of Additional Rent
received by the Agent shall be disbursed by the Agent in accordance with
Article IX of the Deed of Trust.

         Lessor, as promptly as practicable after obtaining knowledge that any
Additional Rent will be payable under this Lease, will advise Lessee, by
written notice, of the amount of any Additional Rent payable hereunder and the
date on which any Additional Rent is due and payable by Lessee in order for
Lessor to meet its obligations with respect to payments by Lessor to other
Persons, but failure to give such notice shall not relieve Lessee of the
obligation to make such payments. Additional Rent shall be paid to Agent or
the Person entitled thereto, on the date specified in Lessor's written notice
to Lessee, by wire transfer of immediately available federal funds using the
wiring instructions set forth in Exhibit D attached hereto. In the event of
any failure by Lessee to pay or discharge any Additional Rent, Lessor shall
have all rights, powers and remedies provided herein or by Law in the case of
non-payment of Basic Rent.

                  (d) In the event that any payment of Basic Rent or
Additional Rent is not made within fifteen (15) days after the date on which
the same is due and payable, Lessee shall pay to whomever shall be entitled
thereto, in each case as Additional Rent, a late charge equal to two percent
(2%) of the overdue amount, together with interest, from the date on which the
payment was due (without regard to any applicable grace period) until the date
such payment is made in full, at the fluctuating rate which is at all times
equal to the LIBO Rate plus 2% per annum (the "Default Rate"). In addition,
Lessee shall pay all costs of collection, including attorneys' fees, if
collection of amounts due to Lessor or any other Person is referred to an
attorney after default by Lessee.

                                      14

<PAGE>

         7. Net Lease; Non-Terminability.

                  (a) This Lease is a net lease, and Basic Rent, Additional
Rent and all other sums payable by Lessee shall be paid without notice or
demand. Lessee's obligations to pay Basic Rent, Additional Rent and all other
such sums payable by Lessee hereunder shall be absolute and unconditional
under any and all circumstances (except as specifically provided herein).

                  (b) Any present or future law to the contrary
notwithstanding, Lessee shall not be entitled to any set-off, counterclaim,
recoupment, abatement, suspension, deferment, diminution, deduction, reduction
or defense of or to Basic Rent or Additional Rent or any other sums payable
hereunder and the obligations of Lessee under this Lease shall not be
affected, for any reason, including the following: (i) any defect in the
condition, merchantability, design, construction or quality of all or any part
of the Property, (ii) any damage to or the destruction of all or any part of
the Property from whatever cause, (iii) any taking of the Property or any
portion thereof or interest therein by condemnation, requisition or otherwise
for any reason, (iv) any prohibition, limitation or restriction of Lessee's
use of all or any part of the Property, or any interference with such use, (v)
any title defect or encumbrance, or any eviction from the Property by
paramount title or otherwise, (vi) Lessee's acquisition or ownership of any
interest in all or any part of the Property otherwise than pursuant to an
express provision of this Lease, (vii) any failure on the part of Lessor to
observe any provision of this Lease, or any default by Lessor under any other
agreement to which Lessor and Lessee may be parties, (viii) any claim which
Lessee has or might have against Lessor, (ix) the impossibility or illegality
of performance by Lessee or Lessor or both, (x) any action by any court,
administrative agency or other Governmental Authority (provided, however, if
any court, administrative agency or other Governmental Authority were to take
any action which would prohibit the payment by Lessee to Lessor of Basic Rent,
Additional Rent or any other sums payable hereunder, Lessor shall, thereafter,
continue to make such payments into an escrow account to be established by the
Agent for the benefit of Lessor and the Credit Facility Providers until such
time as such prohibition on payment by Lessee to Lessor is removed), (xi) the
failure of Lessee, Guarantor or any of their Affiliates to achieve any
accounting or tax benefits or the characterization of the transaction intended
by the parties as set forth in Paragraph 35 hereof, or (xii) any other cause
or circumstance whether similar or dissimilar to the foregoing and whether or
not Lessee shall have notice or knowledge of any of the foregoing. It is the
intention of the parties hereto that the obligations of Lessee hereunder shall
be separate and independent covenants and agreements, that Basic Rent,
Additional Rent and all other sums payable by Lessee hereunder shall continue
to and be payable in all events, and that the obligations of Lessee hereunder
shall continue unaffected, unless the requirement to pay or perform the same
shall have been terminated pursuant to an express provision of this Lease.

                  (c) Lessee agrees that it will remain obligated under this
Lease in accordance with its terms, and that it will not take any action to
terminate, rescind or avoid this Lease or abate the Rent payable hereunder,
notwithstanding (i) the bankruptcy, insolvency, reorganization, composition,
readjustment, liquidation, dissolution, winding-up or other proceeding
affecting Lessor or any assignee of Lessor in any such proceeding or/and (ii)
any other action (including rejection) with respect to this Lease which may be
taken by any trustee or receiver of Lessor or of any assignee of Lessor in any
such proceeding or by any court in any such proceeding, and, in any such
event, so long as Lessee pays and performs its obligations under this Lease
and does

                                      15

<PAGE>

not take any action to terminate, rescind or avoid this Lease or abate the
rent required hereby, Lessee shall be entitled to the benefits of Lessee set
forth in this Lease.

                  (d) Except as otherwise provided in this Lease, Lessee
waives all rights which may now or hereafter be conferred by law (i) to quit,
terminate or surrender this Lease or (ii) to any abatement, suspension,
deferment or reduction of Basic Rent, Additional Rent or any other sums
payable under this Lease.

         8. Payment of Impositions; Compliance with Law, Restrictive Covenants
and Operative Documents.

                  (a) Lessee covenants and agrees to pay, as Additional Rent,
all taxes, charges, levies and assessments which Lessee agrees or is otherwise
obligated to pay under this Lease or any of the other Operative Documents,
including without limitation all amounts described in Section 4.4 of the Deed
of Trust and all Impositions payable by Lessee pursuant to Section 5.4
thereof. If Lessee is not otherwise obligated to furnish proof of payment of
any such amount to Lessor pursuant to other provisions of the Operative
Documents, then Lessee agrees to furnish to Lessor, within thirty (30) days
after written demand therefor, proof of the payment of such amounts.

                  (b) Lessee shall, at its sole cost and expense, promptly
comply with and conform to all Legal Requirements and Insurance Requirements
relating to the Property, including the use and operation thereof, whether or
not compliance therewith shall require structural or extraordinary changes in
the Property or interfere with the use and enjoyment of the Property. Lessee
shall also, at its sole cost and expense, procure, maintain and comply with
all licenses, permits, orders, approvals, consents and other authorizations
required for the use, operation, maintenance, repair and restoration of the
Property.

                  (c) Lessee shall, at its sole cost and expense, promptly
comply with and conform to all of the Restrictive Covenants. (d) Lessee shall,
at its sole cost and expense, perform all obligations of Lessee and of Lessor,
Maryland Trustee and Issuer and pay all amounts due and owing from time to
time under any of the other Operative Documents as and when such obligations
are required to be performed and such amounts are required to be paid,
including, without limitation, the Head Lease, the Deed of Trust and the
Letter of Credit Agreement, provided Lessee is provided with the same notice
and cure period, if any, afforded to the responsible party under the other
Operative Documents.

         9. Liens.

                  (a) Lessee will not, directly or indirectly, create or
permit to remain, and will promptly discharge, at its expense, any mortgage,
lien, encumbrance or charge on, pledge of, or conditional sale or other title
retention agreement with respect to, the Property or any part thereof or
Lessee's interest therein or Basic Rent, Additional Rent or other sums payable
by Lessee under this Lease, other than Permitted Equipment Liens. Lessee, at
its own expense, will promptly pay, satisfy and otherwise take such actions as
may be necessary to keep the Property free and clear of, and duly to
discharge, eliminate or bond in a manner reasonably satisfactory to

                                      16

<PAGE>

Lessor and Agent any of the foregoing liens, other than Permitted Equipment
Liens, if the same shall arise at any time. NOTHING CONTAINED IN THIS LEASE
SHALL BE CONSTRUED AS CONSTITUTING THE CONSENT OR REQUEST OF LESSOR, AGENT OR
ANY CREDIT FACILITY PROVIDER, EXPRESSED OR IMPLIED, OF ANY CONTRACTOR,
SUBCONTRACTOR, LABORER, MATERIALMAN OR VENDOR TO OR FOR THE PERFORMANCE OF ANY
LABOR OR SERVICES OR OTHER FURNISHING OF ANY MATERIALS FOR ANY CONSTRUCTION,
ALTERATION, ADDITION, REPAIR OR DEMOLITION OF OR TO THE PROPERTY OR ANY PART
THEREOF, AND NEITHER LESSOR, AGENT NOR ANY CREDIT FACILITY PROVIDER SHALL BE
LIABLE TO LESSEE OR TO ANY CONTRACTORS, SUBCONTRACTORS, LABORERS, MATERIALMEN,
SUPPLIERS OR VENDORS FOR SERVICES PERFORMED OR MATERIAL PROVIDED ON OR IN
CONNECTION WITH THE PROPERTY OR ANY PART THEREOF.

                  (b) Pursuant to the Operative Documents, including, without
limitation, the Deed of Trust, Lessor, acting through the Maryland Trustee,
and Lessee shall be required to grant various liens on each of their
respective right, title and interest in and to the Property in order to secure
each of their respective obligations under the Operative Documents. Lessor and
Lessee each hereby consent to the granting of any and all such liens required
pursuant to the Operative Documents, including, without limitation, the liens
evidenced by the Deed of Trust.

         10. [INTENTIONALLY RESERVED].

         11. Lessee's Equipment; Building Equipment.

                  (a) All Lessee's Equipment shall remain the property of the
lessor thereof or the property of Lessee, as applicable, notwithstanding its
attachment to the Property. At the expiration or earlier termination of the
Term, all of Lessee's Equipment shall remain the property of the lessor
thereof or the property of the Lessee (as applicable) and shall be removed by
Lessee or such lessor in accordance with subparagraph (c) below.

                  (b) [Intentionally Reserved].

                  (c) Upon the expiration or earlier termination of this
Lease, Lessee shall surrender the Property in good condition, reasonable wear
and tear excepted, with all Building Equipment in good working condition, and
otherwise in the condition required pursuant to the Deed of Trust. Lessee
shall have the right to remove any of Lessee's Equipment prior to the
expiration or earlier termination of this Lease provided (i) no Default or
Event of Default then exists, (ii) Lessee shall repair (and, if necessary,
replace), at its sole cost and expense, any damage to the Property caused by
the removal of Lessee's Equipment (whether affected by Lessee or Lessee's
lessor or any of their agents or employees) and (iii) following the removal of
any of Lessee's Equipment and the repair (and, if necessary, the replacement)
of any damage to the Property caused by such removal, the Property shall have
the same Fair Market Value, remaining useful life, utility and residual value
as existed immediately prior to the removal of such Lessee's Equipment. Any
Lessee's Equipment not removed by Lessee upon the expiration or earlier
termination of this Lease in accordance with the terms of this subparagraph
(c) shall be considered abandoned by Lessee, and may be appropriated, sold,
destroyed or otherwise

                                      17

<PAGE>

disposed of by Lessor without first giving notice thereof and without
obligation to account therefor to either Lessee or any lessor of such Lessee's
Equipment. Lessor shall not be responsible for any loss or damage to Lessee's
Equipment under any circumstances. The provisions of this subparagraph (c) are
not applicable in the event that Lessee exercises the Purchase Option and
irrevocably pays the purchase price provided for in Paragraph 19 hereof to the
Agent.

                  (d) Lessor shall, from time to time upon Lessee's written
request, execute appropriate documents for the benefit of Lessee's lenders or
equipment lessors confirming the provisions of this Paragraph 11 and
containing such further undertakings of Lessor (provided the same are at no
cost and expense to Lessor) concerning the right of any such lender or lessor
to enter the Property prior to the expiration or earlier termination of this
Lease for the purpose of exercising its rights with respect to the collateral
of such lender or lessor, including removing the same, provided such documents
and further undertakings are on commercially reasonable terms and conditions
and require such lender or lessor to fully comply with the terms and
conditions of subparagraph (c) above relating to the removal of Lessee's
Equipment.

         12. Alterations.

                  (a) So long as no Default or Event of Default shall have
occurred and be continuing, Lessee may, at its expense, make Alterations,
subject to the prior written consent of Lessor, Agent and Issuer and further
subject to the terms and conditions of the Head Lease and the Deed of Trust,
provided that Lessee must notify Lessor, Agent and Issuer but not obtain the
prior consent of Lessor, Agent and Issuer for any non-structural Alterations
which do not involve the exterior of any of the Improvements or changes in
utilities, electrical, mechanical or other existing systems and which in each
separate Alteration do not exceed $1,500,000 in cost. Lessor agrees not to
withhold, delay or condition its consent, to the extent required herein,
provided that (i) all such Alterations, construction and installations shall
be performed in a good and workmanlike manner; (ii) all such Alterations,
construction and installations shall be expeditiously completed in compliance
with all Legal Requirements; (iii) all work done in connection with any such
Alterations, construction or installation shall comply with all Insurance
Requirements; (iv) Lessee shall promptly pay all costs and expenses of any
such Alteration, construction or installation and shall discharge all liens
filed against any of the Property arising out of the same; (v) Lessee shall
procure and pay for all permits and licenses required in connection with any
such Alteration, construction or installation; (vi) all such Alterations,
construction and installations shall be the property of Lessor and shall be
subject to this Lease; (vii) the design of any Alterations visible from the
exterior of the Property shall comply with the terms of the Restrictive
Covenants (including obtaining any consents required thereunder), if
applicable; (viii) the contractor performing such alterations shall be
reputable, licensed and insured and shall, if required by Lessor or Agent, be
required to obtain performance and payment bonds; (ix) such Alterations, when
completed, shall not impair the Fair Market Value, utility, remaining useful
life or residual value of the Property from the Fair Market Value, utility,
remaining useful life or residual value thereof immediately prior to the
making thereof; and (x) Lessor shall incur no expense or cost whatsoever in
connection with such Alterations, including without limitation, costs for
reviewing and approving plans, additional common area maintenance fees, tap
fees or other utility fees, and costs incurred by Lessor in obtaining the
approval of the Agent and Issuer, if required pursuant to the Head Lease.
Lessor may require, as

                                      18

<PAGE>

a condition to its consent to any Alterations, reasonable appropriate
payments, assurances and undertakings from Lessee to ensure that all such
conditions are satisfied. Notwithstanding the foregoing, it shall not be
unreasonable for Lessor to withhold its consent, or to condition its consent,
if either the Agent or Issuer withholds its consent to any of the foregoing,
or requires that certain conditions or requirements be satisfied or observed.

                  (b) In the event that any Alterations shall encroach upon
any property, street or right-of-way adjoining or adjacent to the Property, or
shall violate the agreements or conditions contained in any restrictive
covenant affecting the Property or any part thereof, including without
limitation the Restrictive Covenants or shall hinder or obstruct any easement
or right-of-way to which the Property are subject or shall impair the rights
of others under any such easement or right-of-way, then promptly after written
request of Lessor or of any Person affected by any such encroachment,
violation, hindrance, obstruction or impairment, Lessee shall, at its expense,
either (i) obtain valid and effective waivers or settlements of all claims,
liabilities and damages resulting from each such encroachment, violation,
hindrance, obstruction or impairment, whether the same shall affect Lessor,
Lessee or both, or (ii) take such other action as shall be necessary to remove
such encroachments, hindrances or obstructions and to end such violations or
impairments.

         13. Construction of Additional Improvements.

                  (a) Appointment of Lessee as Construction Agent. Pursuant to
and subject to the terms and conditions set forth herein and in the other
Operative Documents, Lessor hereby designates and appoints Lessee, during the
Construction Period, to serve as construction agent for the construction of
the Additional Improvements and acquisition and installation of the related
Building Equipment in accordance with the Plans on the Land. Lessee, acting in
such capacity, shall be referred to in this Paragraph 13 as "Construction
Agent".

                  (b) Acceptance; Construction. Lessee hereby unconditionally
accepts the designation and appointment as Construction Agent. Construction
Agent shall cause the Additional Improvements to be constructed on the Land
and the related Building Equipment to be acquired and installed in accordance
with (i) the Plans, (ii) the terms and conditions set forth in this Lease,
(iii) the terms and conditions of the other Operative Documents and (iv) all
applicable Legal Requirements and Insurance Requirements.

                  (c) Commencement of Construction; Completion Date.
Construction Agent hereby agrees, unconditionally and for the benefit of
Lessor, to cause construction of the Additional Improvements to commence on
the Land as soon as is reasonably practicable, in its reasonable judgment,
after the Commencement Date and to cause construction to be substantially
completed not later than the date which is eighteen (18) months after the
Commencement Date (the "Substantial Completion Date") and to cause all
construction to be completed (including all punchlist items) not later than
the Final Completion Date. For purposes hereof, construction of the Additional
Improvements shall be deemed to commence on the date (the "Construction
Commencement Date") on which excavation for the foundation for such Additional
Improvements commences. Without limiting the foregoing, no phase of such
construction shall be undertaken until all permits for such phase have been
issued therefor.

                                      19

<PAGE>

                  (d) Construction Documents. Construction Agent may execute
any of its duties and obligations under this Paragraph 13 by or through
agents, contractors, employees or attorneys-in-fact, and Construction Agent,
as agent for Lessor, shall enter into such agreements with architects,
contractors and vendors as Construction Agent deems necessary or desirable for
the construction of the Additional Improvements and the acquisition and
installation of the related Building Equipment pursuant hereto (collectively,
the "Construction Documents"); provided, however, that no such delegation
shall limit or reduce in any way Construction Agent's duties and obligations
under this Paragraph 13; provided, further, contemporaneously with the
execution and delivery of any Construction Document, Construction Agent will
execute and deliver to Lessor a Security Agreement and Assignment in the form
attached hereto as Exhibit E and incorporated herein by this reference,
pursuant to which Construction Agent shall assign to Lessor, among other
things, all of Construction Agent's rights under and interests in such
Construction Documents. Each construction contract with a general contractor
or vendor shall be subject to the approval of Lessor and Agent, shall be with
a reputable general contractor or vendor with experience in constructing or
equipping projects that are similar in scope and type to the Additional
Improvements, shall provide for a fixed price or guaranteed maximum price
(unless otherwise specifically agreed to by Agent) and shall provide that the
general contractor shall insure the Additional Improvements under a "builders'
risks" property insurance policy (unless provided by Construction Agent).
Construction Agent shall provide (or cause to be provided) such payment and
performance bonds as may be required by Agent.

                  (e) Scope of Authority.

                           (i)      Subject to the terms, conditions,
         restrictions and limitations set forth herein and in the other
         Operative Documents, Lessor hereby expressly authorizes Construction
         Agent, or any agent or contractor of Construction Agent, and
         Construction Agent unconditionally agrees, for the benefit of Lessor,
         to take all action necessary or desirable for the performance and
         satisfaction of all of Construction Agent's obligations under this
         Paragraph 13 with respect to the construction of the Additional
         Improvements and the acquisition and installation of the related
         Building Equipment, including, without limitation:

                                    (A) overseeing, directing, supervising and
                  monitoring all design and supervisory functions relating to
                  the construction of the Additional Improvements and
                  acquisition and installation of the related Building
                  Equipment and all engineering work related to the
                  construction of the Additional Improvements and acquisition
                  and installation of the related Building Equipment;

                                    (B) negotiating and entering into all
                  contracts or arrangements to procure the equipment and
                  services necessary to construct the Additional Improvements
                  and acquisition and installation of the related Building
                  Equipment on such terms and conditions as are customary and
                  reasonable in light of local standards and practices;

                                    (C) obtaining all necessary permits,
                  licenses, consents, approvals and other authorizations,
                  including those required under Law (including Environmental
                  Laws), from all Governmental Authorities in connection with
                  the

                                      20

<PAGE>

                  construction of the Additional Improvements on the Land and
                  the acquisition and installation of the related Building
                  Equipment in accordance with the Plans;

                                    (D) maintaining all books and records with
                  respect to the construction of the Additional Improvements;
                  and

                                    (E) performing any other acts necessary or
                  appropriate in connection with the construction of the
                  Additional Improvements and acquisition and installation of
                  the related Building Equipment in accordance with the Plans.

                           (ii)     Neither the Construction Agent nor any of
         its Affiliates or agents shall enter into any contract which would,
         directly or indirectly, impose any liability or obligation on Lessor
         unless such contract expressly contains an acknowledgment by the
         other party or parties thereto that the obligations of Lessor are
         non-recourse, and that Lessor shall have no personal liability with
         respect to such obligations. Subject to the foregoing, Lessor shall
         execute such documents and take such other actions as Construction
         Agent shall reasonably request, at Construction Agent's expense, to
         permit Construction Agent to perform its duties hereunder.

                           (iii)    Subject to the terms and conditions of
         this Lease and the other Operative Documents, Construction Agent
         shall have sole management and control over the construction means,
         methods, sequences and procedures with respect to the construction of
         the Additional Improvements and acquisition and installation of the
         related Building Equipment.

                  (f) Covenants of Construction Agent.  Construction Agent
hereby covenants and agrees that it will:

                           (i)      following the Construction Commencement
         Date, cause construction of the Additional Improvements on the Land
         and acquisition and installation of the related Building Equipment to
         be prosecuted diligently and without undue interruption substantially
         in accordance with the Plans and in compliance in all material
         respects with all Legal Requirements and Insurance Requirements and
         cause Substantial Completion to occur by the Substantial Completion
         Date and final completion to occur by the Final Completion Date;

                           (ii)     cause all liens (including, without
         limitation, liens or claims for materials supplied or labor or
         services performed in connection with the construction of the
         Additional Improvements and acquisition and installation of the
         related Building Equipment), other than the Encumbrances and Lessor
         Liens, to be discharged or bonded off if disputed in good faith by
         appropriate proceedings by Construction Agent;

                           (iii)    cause all outstanding punch list items
         with respect to the Additional Improvements and the related Building
         Equipment to be completed within ninety (90) days after the
         Substantial Completion Date (the "Final Completion Date"); provided,
         however, the Lessee acknowledges and agrees that the Lessee shall not
         be permitted to capitalize interest and yield, fees and insurance
         premiums due under the Operative Documents beyond the Substantial
         Completion Date; and

                                      21

<PAGE>

                           (iv)     at all times during construction of the
         Additional Improvements and acquisition and installation of the
         related Building Equipment, cause all title to all personalty
         financed by Lessor on or within the Property to be and remain vested
         in Lessor and cause to be on file with the applicable filing office
         or offices all necessary documents under Article 9 of the Uniform
         Commercial Code to perfect such title free of all liens other than
         Encumbrances, it being understood and acknowledged that Lessor's
         rights, title and interest in and to said personalty have been
         assigned to Agent pursuant to the Operative Documents.

                  (g) Amendments to Plans and Construction Documents.
Construction Agent may not amend or modify the Plans or any of the
Construction Documents without the prior written consent of Lessor and Agent,
unless such amendment or modification (i) involves a non-structural change to
the Additional Improvements, (ii) would not cause Substantial Completion to be
delayed beyond the Substantial Completion Date and (iii) would not cause the
undisbursed portion of the budget for the construction of the Additional
Improvements prepared by Lessee pursuant to the Deed of Trust and delivered to
Agent to be insufficient to pay all remaining costs associated with the
construction of the Additional Improvements.

                  (h) No Agency Fee. All obligations, duties and requirements
imposed upon or allocated to Construction Agent under this Paragraph 13 shall
be performed by Construction Agent at Construction Agent's sole cost and
expense, and Construction Agent will not be entitled to, and Lessor shall not
have any obligation to pay, any agency fee or other fee or compensation, and
Construction Agent shall not be entitled to, and Lessor shall not have any
obligation to make or pay, any reimbursement therefor, it being understood
that the terms and provisions of this Paragraph 13 are being incorporated into
this Lease as consideration for and as an inducement to Lessor entering into
this Lease and the other Operative Documents.

                  (i) Construction Monitoring. During the Construction Period,
the Agent shall have the right, from time to time, at the sole cost and
expense of Lessee, to have a third party construction consultant (the
"Construction Consultant") inspect the construction of the Additional
Improvements on the Property and provide a report to the Agent regarding the
status of such construction and Lessee's compliance with the terms and
conditions of this Paragraph 13 and the other Operative Documents regarding
such construction (the "Construction Consultant Report"). If the Construction
Consultant Report reveals any deficiencies in the construction of the
Additional Improvements by the Lessee, Lessee shall promptly remedy any such
deficiencies and provide evidence thereof reasonably acceptable to the Agent
and the Construction Consultant.

         14. Insurance.  During the Term, Lessee covenants and agrees, at
Lessee's cost and expense, to maintain the insurance required to be maintained
by Lessee pursuant to the Deed of Trust.

         15. Assignment and Subletting.

                  (a) Provided no Default or Event of Default shall have
occurred and be continuing, with prior written notice to Lessor and the Agent,
Lessee may, provided such use of the Property or the applicable portion
thereof is limited to the Permitted Use, sublet all or any

                                      22

<PAGE>

portion of the Property to (i) an Affiliate or (ii) Invitrogen (the
"Invitrogen Sublease"), provided that the term of the Invitrogen Sublease
shall not extend beyond April 30, 2002, or assign this Lease to an Affiliate.
Provided no Default or Event of Default or event which, with the giving of
notice or the lapse of time or both, would constitute an Event of Default,
shall have occurred and be continuing, with the prior written consent of
Lessor and the Agent (which consent shall not be unreasonably withheld),
Lessee may sublet all or any part of the Property to any Person which is not
an Affiliate, or assign this Lease to any Person which is not an Affiliate,
provided in each instance such Person shall use the Property solely for the
Permitted Use. Notwithstanding the foregoing, it shall not be unreasonable for
Lessor to withhold its consent, or to condition its consent, if the Agent or
Issuer withholds its consent to any assignment or subletting, or requires that
certain conditions or requirements be satisfied or observed. Lessee shall give
Lessor at least thirty (30) days' advance written notice of its intention to
enter into any transaction governed by this Paragraph 15, together with such
information as Lessor and/or the Agent may reasonably request concerning the
business and financial background of the proposed sublessee or assignee.
Within ten (10) days after the execution and delivery of any assignment or
sublease permitted pursuant to this Paragraph 15, Lessee shall deliver a
conformed copy thereof to Lessor and the Agent, and within ten (10) days after
the execution and delivery of any permitted sublease, Lessee shall give notice
to Lessor and the Agent of the existence and term thereof, and of the name and
address of the sublessee thereunder.

                  (b) No assignment or sublease permitted hereunder will (i)
release Lessee of any obligations hereunder or under any of the other
Operative Documents or affect or reduce any of the obligations of Lessee
hereunder, and all such obligations shall continue in full effect as
obligations of a principal and not as obligations of a guarantor or surety, to
the same extent as though no assignment or subletting had been made, (ii)
impose any obligations on Lessor beyond those of Lessor under this Lease or
otherwise affect any of the rights of Lessor under this Lease or (iii) extend
beyond the last day of the Term. Each assignment or sublease permitted hereby
shall be made and shall expressly provide that it is subject and subordinate
to this Lease and the rights of Lessor hereunder, and shall expressly provide
for the surrender of the Property or the applicable portion thereof that is
subleased by the applicable sublessee at the election of Lessor after the
occurrence and continuance of an Event of Default. Notwithstanding the
foregoing, however, Lessor covenants and agrees that, following the occurrence
and continuance of a Default or an Event of Default, Invitrogen shall be
entitled to remain in possession of that portion of the Property then being
subleased by Invitrogen pursuant to the Invitrogen Sublease, provided
Invitrogen is not then in default under such sublease and Invitrogen agrees to
attorn to Lessor or any subsequent owner of the Property for the remainder of
the term of such sublease. The effectiveness of an assignment hereunder shall
be conditioned upon the receipt by Lessor and the Agent of a writing executed
by the assignee pursuant to which the assignee shall expressly assume all of
the obligations of Lessee hereunder. Any assignment or subletting, Lessor's
consent thereto, or Lessor's collection or acceptance of rent from any
assignee or sublessee shall not be construed either as waiving or releasing
Lessee from any of its liabilities or obligations under this Lease, or as
relieving Lessee or any assignee or sublessee from the obligation of obtaining
Lessor's and the Agent's prior written consent to any subsequent assignment or
subletting.

                  (c) Upon the occurrence of an Event of Default under this
Lease, Lessor shall have the right to collect and enjoy all rents and other
sums of money payable under any sublease

                                      23

<PAGE>

of any of the Property, and Lessee hereby irrevocably and unconditionally
assigns such rents and money to Lessor, which assignment may be exercised upon
and after (but not before) the occurrence of an Event of Default. From and
after the date, if any, that such Event of Default is cured, such rents shall
again become payable to Lessee and the excess, if any, of the sublease rents
collected by Lessor over the amount thereof applied toward Lessee's
obligations under this Lease shall be paid to Lessee.

                  (d) All restrictions and obligations imposed pursuant to
this Lease on Lessee shall be deemed to extend to any sublessee or assignee,
and Lessee shall cause such Person to comply with such restrictions and
obligations.

                  (e) Any assignment or sublease not made in accordance with
the terms of this Paragraph 15 shall be void.

         16. Permitted Contests. Notwithstanding any other provision of this
Lease to the contrary, Lessee shall not be required to (i) pay any Imposition,
(ii) discharge or remove any lien, encumbrance or charge referred to in
Paragraph 9 or 11 or (iii) comply with any Insurance Requirement so long as
Lessee shall contest, in good faith and at its expense, the existence, the
amount or the validity thereof, the amount of the damages caused thereby, or
the extent of its liability therefor, by appropriate proceedings, provided
that (a) such contest shall operate at all times during the pendency thereof
to prevent (i) the collection of, or other realization upon, the sums payable
to satisfy any Imposition or lien, encumbrance or other charge so contested,
and (ii) the sale, forfeiture or loss of the Property, or any part thereof, or
any interest therein or Basic Rent or any Additional Rent, or any portion
thereof, (b) such contest shall not result in any interference or potential
interference with the use or occupancy of the Property or any part thereof,
(c) there shall be no interference with the payment of Basic Rent or any
Additional Rent, or any portion thereof as a result of such contest, (d) there
shall be no cancellation or interruption of any fire or other insurance policy
as a result of such contest, unless such policy is replaced prior to its
cancellation by another policy complying with the provisions of this Lease,
and (e) such content shall not result in the Imposition or potential
Imposition of any civil or criminal liability upon Lessor. While any such
proceedings are pending, Lessor shall not have the right to pay, remove or
cause to be discharged the tax, assessment, levy, fee, rent or charge or lien,
encumbrance or charge thereby being contested or to take steps necessary to
comply with any Insurance Requirements thereby being contested, provided that
Lessor shall have the right to require Lessee to establish reasonable reserves
for such liabilities being contested if the Lessor reasonably determines such
reserves to be necessary. Lessee further agrees to give Lessor prompt notice
of Lessee's intention to contest any Imposition or Insurance Requirements and
that each such contest shall be promptly prosecuted to a final conclusion.
Lessee will pay, and save Lessor and the Agent harmless against, any and all
losses, judgments, decrees and costs (including all reasonable attorneys' fees
and expenses) in connection with any such contest and will, promptly after the
final settlement, compromise or determination of such contest, fully pay and
discharge the amounts which shall be levied, assessed, charged or imposed or
be determined to be payable therein or in connection therewith, together with
all penalties, fines, interests, costs and expenses thereof or in connection
therewith, and perform all acts the performance of which shall be ordered or
decreed as a result thereof.

         17. Default Provisions.

                                      24

<PAGE>

                  (a) Events of Default.  Any of the following occurrences or
acts shall constitute an Event of Default under this Lease:

                           (i)      Lessee shall fail to pay any installment
         of Rent within five (5) Business Days after notice from Lessor and/or
         Agent that the same is due or any other amounts required to be paid
         by Lessee hereunder or under the other Operative Documents, as and
         when the same become due, unless any notice and cure period is
         expressly provided for herein or in the other Operative Documents, in
         which case Lessee shall be afforded such notice and cure period.

                           (ii)     Lessee shall fail to pay any amounts
         payable pursuant to Paragraph 18(a), 18(b), 19(d), 19(f) and 19(g)
         hereof as and when due.

                           (iii)    Lessee shall fail to maintain the
         insurance required pursuant to Paragraph 14 hereof.

                           (iv)     Lessee shall fail to purchase the Property
         in accordance with Paragraph 19(c) below, or Lessee shall fail to
         sell all of the Property by the Expiration Date in accordance with
         the terms of Paragraph 19(f) below following the exercise by Lessee
         of the Remarketing Option.

                           (v)      Lessee shall fail to cure any deficiency
         in the Collateral (as defined in the Collateral Pledge Agreement)
         within two (2) Business Days after notice from the Agent and/or the
         Trustee.

                           (vi)     The occurrence of an event of default
         under the Credit Facility Agreements or the failure to reimburse any
         drawing under the Letter of Credit in accordance with the Credit
         Facility Agreements (including, without limitation, any drawing as a
         result of a default or failure to replace any Letter of Credit),
         provided Lessee is provided with the same notice and cure period, if
         any, afforded to the responsible party under the Credit Facility
         Agreements.

                           (vii)    Lessee shall fail to observe or perform
         any other covenant, condition or agreement contained in this Lease or
         any other Operative Document (except as expressly provided herein)
         and such failure shall continue unremedied for a period of thirty
         (30) days (or such shorter period of time as Lessor and/or the Agent
         may reasonably determine if such default endangers life or property)
         after Lessor and/or the Agent shall have delivered to Lessee written
         notice (except in the case of an emergency) of such failure (provided
         that, in the case of any default referred to in this clause (vii)
         which does not endanger life or property and which cannot with
         diligence be cured within such thirty (30) day period, if Lessee
         shall proceed promptly to cure the same and thereafter shall
         prosecute the curing of such default with diligence, then upon
         receipt by Lessor and the Agent of a certificate from an authorized
         officer of Lessee stating the reason that such default cannot be
         cured within thirty (30) days and stating that Lessee is proceeding
         with diligence to cure such default, the time within which such
         failure may be cured shall be extended for such additional period as
         may be necessary to complete the curing of the same with diligence.

                                      25

<PAGE>

                           (viii)   An Act of Bankruptcy occurs with respect
         to Lessee, or Lessee becomes generally unable to pay its debts as
         they become due; provided, however, if a proceeding with respect to
         an Act of Bankruptcy is filed or commenced against Lessee, the same
         shall not constitute an Event of Default if such proceeding is
         dismissed within ninety (90) days from the date of such Act of
         Bankruptcy.

                           (ix)     Default is made (A) with respect to any
         evidence of indebtedness or liability for borrowed money of Lessee to
         any of the Credit Facility Providers, or (B) with respect to any
         evidence of indebtedness or liability of Lessee to any other Person
         for borrowed money or pursuant to a lease obligation, if the effect
         of such default described in clause (A) or (B) above is to accelerate
         the maturity of such evidence of indebtedness or liability prior to
         its stated maturity (whether automatically, following an election by
         the holder or obligee thereof to accelerate, or otherwise) or any
         such indebtedness is not paid as and when due and payable; provided,
         however, that it shall not constitute an Event of Default if the
         outstanding principal balance of such indebtedness or liability of
         Lessee to any Person other than any of the Credit Facility Providers
         is not in excess of $10,000,000 or Lessee certifies to the Credit
         Facility Providers that it is contesting such default in good faith
         and by appropriate and diligent proceedings.

                           (x)      Lessee abandons the Property.

                           (xi)     [Intentionally Omitted.]

                           (xii)    The interest of Lessee in the Property or
         any part thereof shall be assigned or subleased in violation of
         Paragraph 15, or shall be levied upon or attached in any proceeding
         involving a claim in excess of $2,500,000 and such proceeding is not
         vacated, discharged or bonded against to the reasonable satisfaction
         of Lessor and the Agent within thirty (30) days thereafter.

                           (xiii)   Any representation or warranty made by
         Lessee or its representatives in this Lease or any of the other
         Operative Documents executed and delivered by Lessee or any statement
         or representation made by Lessee or its representatives in any
         certificate, report or opinion (including legal opinions) financial
         statement or other instrument furnished in connection with this Lease
         or any of the Operative Documents executed and delivered by Lessee
         proves to have been incorrect, false or misleading in any material
         respect when made.

                           (xiv)    Any judgment against Lessee or any
         attachment or other levy against the property of Lessee with respect
         to a claim for an amount in excess of $10,000,000 remains unpaid,
         unstayed on appeal, undischarged, unbonded or undismissed for a
         period of sixty (60) days.

                           (xv)     Lessee fails to comply with any material
         requirement of any Governmental Authority having jurisdiction over
         the Property within the time required by such Governmental Authority;
         or any proceeding is commenced or action taken to enforce any remedy
         for a violation of any material requirement of a Governmental
         Authority or any restrictive covenant affecting the Property or any
         part thereof; provided,

                                      26

<PAGE>

         however, it shall not constitute an Event of Default during the
         pendency of any contest if Lessee is contesting the validity or
         applicability of any such requirement or covenant, at its sole cost
         and expense, in good faith and by appropriate and diligent
         proceedings in accordance with the terms of Paragraph 16 hereof.

                           (xvi)    If any material provision of this Lease or
         any of the other Operative Documents at any time for any reason
         ceases to be valid and binding on Lessee, or is declared to be null
         and void, or the validity or enforceability thereof is contested by
         Lessee or any governmental agency or authority, or Lessee denies that
         it has any further liability or obligation under this Lease or any of
         the other Operative Documents executed and delivered by Lessee.

                           (xvii)   Lessee fails to achieve Substantial
         Completion of the Additional Improvements for any reason prior to the
         Substantial Completion Date.

                           (xviii)  Lessee fails to achieve final completion
         of the Additional Improvements for any reason prior to the Final
         Completion Date.

                           (xix)    If, at any time, the undisbursed portion
         of the budget for the construction of the Additional Improvements
         prepared by Lessee pursuant to the Deed of Trust and delivered to
         Agent becomes insufficient to pay all costs associated with the
         construction of the Additional Improvements.

                  (b) Remedies. During the existence of an Event of Default,
at Lessor's option and without limiting Lessor in the exercise of any other
right or remedy Lessor may have on account of such Event of Default
(including, without limitation, the obligation of Lessee to purchase the
Property as set forth below), and without any further demand or notice, Lessor
may cause the following to occur:

                           (i)      By notice to Lessee, Lessor may terminate
         Lessee's right to possession of the Property. A notice given in
         connection with unlawful detainer proceedings specifying a time
         within which to cure a default shall terminate Lessee's right to
         possession if Lessee fails to cure the default within the time
         specified in the notice.

                           (ii)     Upon termination of Lessee's right to
         possession and without further demand or notice, Lessee shall
         surrender possession and vacate the Property and deliver possession
         thereof in the condition required by Paragraph 11(c) of this Lease,
         and Lessor may re-enter the Property and remove any Persons in
         possession thereof.

                           (iii)    Lessor may terminate this Lease with
         respect to the Property and/or declare the aggregate outstanding
         Lease Balance to be immediately due and payable, and Lessor shall be
         entitled to (x) recover from Lessee the following amounts and (y)
         take the following actions:

                                    (A) Lessee shall pay all accrued and
                  unpaid Rent hereunder (including, without limitation, Basic
                  Rent and Additional Rent) for the period

                                      27

<PAGE>

                  commencing on the Commencement Date through the Final Rent
                  Payment Date (as hereinafter defined) with respect to the
                  Property;

                                    (B) Lessor may elect either of the
                  following with respect to the Property:

                                             (1) Lessor may demand, by written
                           notice to Lessee specifying a payment date (the
                           "Final Rent Payment Date") not earlier than ten
                           (10) days after the date of such notice, that
                           Lessee purchase the Property, and Lessee shall pay
                           to Lessor, on the Final Rent Payment Date (in lieu
                           of Basic Rent due after the Final Rent Payment
                           Date), an amount equal to the sum of (A) the Lease
                           Balance computed for the period commencing on the
                           Commencement Date to and including the Final Rent
                           Payment Date, plus (B) all accrued and unpaid Rent
                           due and unpaid for the period commencing on the
                           Commencement Date to and including the Final Rent
                           Payment Date, and upon payment of such amount, and
                           the amount of all other sums due and payable under
                           this Lease and the other Operative Documents (and
                           interest at the Default Rate on the amounts payable
                           under this clause (B)(1) from the Final Rent
                           Payment Date to the date of actual payment), Lessor
                           shall transfer to Lessee all of Lessor's right,
                           title and interest in and to the Property pursuant
                           to Paragraph 19(e) below; or

                                             (2) Lessor may sell its interest
                           in the Property and the other applicable Lessee
                           Collateral, in which event, Lessee shall pay to
                           Lessor an amount equal to the excess, if any, of
                           (x) all amounts due Lessor under clause (B)(1)
                           above over (y) the net sale proceeds received by
                           Lessor from the foregoing sale (provided, that in
                           calculating such net sale proceeds, all expenses
                           and Impositions incurred by Agent, Lessor and any
                           of the Credit Facility Providers in connection with
                           such sale, including, without limitation, legal
                           fees, shall be deducted from such sale proceeds);

                                    (C) Any other amount necessary to
                  compensate Lessor for all the damages proximately caused by
                  Lessee's failure to perform Lessee's obligation under this
                  Lease or which in the ordinary course of things would be
                  likely to result therefrom, including, but not limited to,
                  the costs and expenses (including without limitation,
                  reasonable attorneys' fees, advertising costs and brokers'
                  commissions) of recovering possession of the Property,
                  removing Persons or property therefrom, placing the Property
                  in good order, condition, and repair, preparing and altering
                  the Property for reletting, and all other costs and expenses
                  of reletting; and

                                    (D) Such other amounts in addition to or
                  in lieu of the foregoing as may be permitted from time to
                  time by Law.

                           (iv)     Lessor may enforce the Lien given
         hereunder pursuant to Paragraph 36 hereof, the UCC or any other Law
         to recover all amounts due and owning

                                      28

<PAGE>

         under the Operative Documents, including, without limitation, the
         Lease Balance, any indemnity obligations of the Lessee under the
         Operative Documents then due and owing, any amounts due under the
         Hedge Documents and any amounts due under the Credit Facility
         Documents.

                           (v)      If Lessee has breached this Lease, this
         Lease shall continue in effect for so long as Lessor does not
         terminate this Lease, and Lessor may enforce all of Lessor's rights
         and remedies under this Lease, including the right to recover the
         Rent hereunder (including, without limitation, Basic Rent (when
         applicable) and Additional Rent) as it becomes due under this Lease.
         Lessee's right to possession shall not be deemed to have been
         terminated by Lessor except pursuant to clause (iii) above. The
         following do not constitute a termination of this Lease:

                                    (A) Acts of maintenance or preservation or
                  efforts to relet the Property;

                                    (B) The appointment of a receiver upon the
                  initiative of Lessor to protect Lessor's interest under this
                  Lease; or

                                    (C) Withholding of consent to an
                  assignment or subletting, or terminating a subletting or
                  assignment by Lessee.

                           (vi)     In the event that Lessor elects to
         continue this Lease in full force and effect following the
         termination of Lessee's right of possession, Lessor, to the maximum
         extent permitted by Law, may enforce all its rights and remedies
         under this Lease, including, but not limited to, the right to recover
         Rent hereunder as it becomes due.  During the continuance of an Event
         of Default or following the termination of Lessee's right to
         possession, Lessor may enter the Property in accordance with Law
         without terminating this Lease and sublet all or any part of the
         Property for Lessee's account to any Person, for such term (which may
         be a period beyond the remaining Term), at such rents and on such
         other terms and conditions as are commercially reasonable.  In the
         event of any such subletting, rents received by Lessor from such
         subletting shall be applied (a) first, to the payment of the
         reasonable costs incurred by Lessor in maintaining, preserving,
         altering and preparing the Property for subletting and other
         reasonable costs of subletting, including, but not limited to,
         brokers' commissions and attorneys' fees; (b) second, to the payment
         of Rent hereunder then due and payable; (c) third, to the payment of
         future Rent hereunder as the same may become due and payable
         hereunder; (d) fourth, to the payment of all other obligations of
         Lessee hereunder and under the other Operative Documents (including,
         without limitation, the Lease Balance), and (e) fifth, the balance,
         if any, shall be paid to Lessee upon (but not before) expiration of
         the Term.  If the rents received by Lessor from such subletting,
         after application as provided above, are insufficient in any period
         to pay the Rent due and payable hereunder for such period, Lessee
         shall pay such deficiency to Lessor upon demand.  Notwithstanding any
         such subletting for Lessee's account without termination, Lessor may
         at any time thereafter, by written notice to Lessee, elect to
         terminate this Lease.

                                      29

<PAGE>

                           (vii)    Lessor may exercise any other right or
         remedy that may be available to it under Law, this Lease and the
         other Operative Documents or in equity, or proceed by appropriate
         court action (legal or equitable) to enforce the terms or to recover
         damages for the breach hereof, including those arising from a breach
         by Lessee of its obligation to purchase the Property pursuant to
         Paragraph 19(c). Separate suits may be brought to collect any such
         damages for any Rent installment period(s), and such suits shall not
         in any manner prejudice Lessor's right to collect any such damages
         for any subsequent Rent installment period(s), or Lessor may defer
         any such suit until after the expiration of the Term, in which event
         such suit shall be deemed not to have accrued until the expiration of
         the Term.

                           (viii)   Lessor may retain and apply against
         Lessor's damages all sums which Lessor would, absent such Event of
         Default, be required to pay to, or turn over to, Lessee pursuant to
         the terms of this Lease.

                           (ix)     As a matter of right and without notice to
         Lessee or anyone claiming under Lessee, and without regard to the
         then value of the Lessee Collateral or the interest of Lessee
         therein, Lessor shall have the right to apply to any court having
         jurisdiction to appoint a receiver or receivers of the Lessee
         Collateral at Lessee's sole cost and expense, and Lessee hereby
         irrevocably consents to such appointment and waives notice of any
         application therefor.  Any such receiver or receivers shall have all
         the usual powers and duties of receivers in like or similar cases and
         all the powers and duties of Lessor in case of entry as provided in
         this Lease and shall continue as such and exercise all such powers
         until the latest to occur of (i) the date of confirmation of sale of
         the Lessee Collateral; (ii) the disbursement of all proceeds of the
         Lessee Collateral collected by such receiver and the payment of all
         expenses incurred in connection therewith; or (iii) the termination
         of such receivership with the consent of Lessor or pursuant to an
         order by a court of competent jurisdiction.

         Lessee acknowledges and agrees that upon the declaration of an Event
of Default the amount due and owing by Lessee to Lessor hereunder shall be the
Lease Balance and that to the maximum extent permitted by Law, Lessee waives
any right to contest the Lease Balance as the liquidated sum due upon
acceleration of this Lease. The foregoing waiver shall only be a waiver by
Lessee of any right to contest the validity of the Lease Balance as a
liquidated sum due upon acceleration of this Lease and shall not be deemed a
waiver of Lessee's rights hereunder to contest the amount of the Lease
Balance.

                  (c) Proceeds of Sale; Deficiency. All payments received and
amounts held or realized by Lessor at any time when an Event of Default shall
be continuing and after the Lease Balance shall have been accelerated pursuant
to this Paragraph 17 as well as all payments or amounts then held or
thereafter received by Lessor (except for rents received by Lessor from
subletting pursuant to Paragraph 17(b)(vi), which shall be distributed as set
forth therein) and the proceeds of sale pursuant to Paragraph 17(b)(iii)(B)(2)
shall be distributed to the Agent upon receipt by Lessor for distribution in
accordance with the terms of the Deed of Trust.

                  (d) Waiver of Certain Rights. (a) To the maximum extent
permitted by law, Lessee hereby waives the benefit of any appraisement,
valuation, stay, extension, reinstatement

                                      30

<PAGE>

and redemption laws now or hereafter in force and all rights of marshalling in
the event of any sale of the Property or any interest therein, (b) if this
Lease shall be terminated pursuant to this Paragraph 17, Lessee waives, to the
fullest extent permitted by law, (i) any notice of re-entry or the institution
of legal proceedings to obtain re-entry or possession; (ii) any right of
redemption, re-entry or repossession; (iii) the benefit of any laws now or
hereafter in force exempting property from liability for rent or for debt or
limiting Lessor with respect to the election of remedies; and (iv) any other
rights which might otherwise limit or modify any of Lessor's rights or
remedies under this Paragraph 17.

                  (e) Remedies Cumulative; No Waiver; Consents. To the extent
permitted by, and subject to the mandatory requirements of, Law, each and
every right, power and remedy herein specifically given to Lessor or otherwise
in this Lease shall be cumulative and shall be in addition to every other
right, power and remedy herein specifically given or now or hereafter existing
at law, in equity or by statute, and each and every right, power and remedy
whether specifically herein given or otherwise existing may be exercised from
time to time and as often and in such order as may be deemed expedient by
Lessor, and the exercise or the beginning of the exercise of any power or
remedy shall not be construed to be a waiver of the right to exercise at the
same time or thereafter any other right, power or remedy. No delay or omission
by Lessor in the exercise of any right, power or remedy or in the pursuit of
any remedy shall impair any such right, power or remedy or be construed to be
a waiver of any default on the part of Lessee or be an acquiescence therein.
Lessor's consent to any request made by Lessee shall not be deemed to
constitute or preclude the necessity for obtaining Lessor's consent, in the
future, to all similar requests. No express or implied waiver by Lessor of any
Event of Default shall in any way be, or be construed to be, a waiver of any
future or subsequent Event of Default. To the extent permitted by Law and
subject to the provisions of this Paragraph 17, Lessee hereby waives any
rights now or hereafter conferred by statute or otherwise that may require
Lessor to sell, lease or otherwise use the Property, the other Lessee
Collateral or any part thereof in mitigation of Lessor's damages upon the
occurrence of an Event of Default or that may otherwise limit or modify any of
Lessor's rights or remedies under this Paragraph 17.

         18. Additional Rights of Lessor.

                  (a) In the event Lessee shall be in default in the
performance of any of its obligations under this Lease, and an action shall be
brought for the enforcement thereof in which it shall be determined that
Lessee was in default, Lessee shall pay to Lessor all the expenses incurred in
connection therewith including reasonable attorney's fees. In the event Lessor
shall, without fault on its part, be made a party to any litigation commenced
against Lessee, and if Lessee, at its expense, shall fail to provide Lessor
with counsel reasonably approved by Lessor, Lessee shall pay all costs and
reasonable attorney's fees incurred or paid by Lessor in connection with such
litigation.

                  (b) If an Event of Default has occurred and is continuing,
Lessor may, but shall not be obligated to, make any payment or perform any act
required hereunder to be made or performed by Lessee which has not been
performed within the time period specified herein for such performance, with
the same effect as if made or performed by Lessee, provided that no entry by
Lessor upon the Property for such purpose shall create any liability to Lessee
on the part of Lessor or shall constitute or shall be deemed to be an eviction
of Lessee, and no such entry

                                      31

<PAGE>

shall waive or release Lessee from any obligation or default hereunder. All
sums so paid by Lessor and all costs and expenses (including reasonable
attorney's fees and expenses) incurred by Lessor in connection with the
performance of any such act, together with interest at the Default Rate, shall
constitute Additional Rent payable by Lessee hereunder.

         19. Sale, Return or Purchase of Property.

                  (a)      (i) Lessee's Option to Purchase. Subject to the
terms, conditions and provisions set forth in this Paragraph 19, the Lessee
shall have the option (the "Purchase Option"), on any Payment Date occurring
two (2) years after the Commencement Date, to be exercised as set forth below,
to purchase from the Lessor, the Lessor's right, title and interest in all
(but not less than all) of the Property. Such option must be exercised by
written notice to the Lessor not later than sixty (60) days prior to the
applicable Payment Date, which notice shall be irrevocable. If the Purchase
Option is exercised pursuant to the foregoing, then, upon payment of the
purchase price set forth in subparagraph (d) below and subject to the
provisions set forth in this Paragraph 19, on the applicable Payment Date, the
Lessor shall convey to the Lessee, without recourse or warranty, other than a
warranty against the existence of any Lessor Liens, and the Lessee shall
purchase from the Lessor, the Lessor's right, title and interest in the
Property. Notwithstanding anything contained herein or in the Operative
Documents to the contrary, upon receipt by the Trustee of the certificate
attached as Exhibit I to the Letter of Credit, the Lessee shall be deemed to
have exercised either (i) its option to purchase the Property for the Lease
Balance, in which case the Lessee shall pay the Lease Balance to the Agent on
or before the expiration or termination of the Letter of Credit and, upon
receipt by the Agent of the Lease Balance, the Lessor shall convey to the
Lessee the Lessor's right, title and interest in the Property in accordance
with this Paragraph 19, or (ii) the option to purchase the beneficial interest
in the Owner Trust.

                           (ii) Lessee's Option to Purchase Owner Trust Estate
and Replace Credit Facility Provider. In addition to the Purchase Option
provided in subparagraph (a)(i) above, the Lessee shall also have the option,
(a) on any Payment Date occurring two (2) years after the Commencement Date or
(b) at any time following a Downgrade, to purchase the beneficial interest in
the Owner Trust Estate and to replace the Credit Facility Providers by paying
to the Agent an amount equal to the sum of (A) the aggregate sum of the
outstanding principal amount of the Certificates as of such Payment Date, plus
all accrued and unpaid Holder Yield thereon as of such Payment Date and (B)
all amounts due and owing under the Operative Documents as of such Payment
Date, including, without limitation, all sums due and owing under the Hedge
Documents and the Credit Facility Documents. The option provided for in clause
(a) above must be exercised by written notice to the Lessor not later than
sixty (60) days prior to the applicable Payment Date, which notice shall be
irrevocable.

                  (b) Conveyance to Lessee. Unless (i) the Lessee shall have
properly exercised the Purchase Option and purchased the Lessor's right, title
and interest in the Property pursuant to subparagraph (a) above, or (ii) the
Lessee shall have properly exercised the Remarketing Option and shall have
fulfilled all of the conditions of subparagraph (f) hereof, then, subject to
the terms, conditions and provisions set forth in this Paragraph 19, the
Lessee shall purchase from the Lessor, and the Lessor shall convey to the
Lessee, on the Expiration Date all of the Lessor's right, title or interest in
the Property, free and clear of any Lessor Liens for the purchase price set

                                      32

<PAGE>

forth in subparagraph (d) below. The Lessee may designate, in a notice given
to the Lessor not less than ten (10) Business Days prior to the closing of
such purchase, or any purchase pursuant to subparagraph (a) above, (time being
of the essence), the transferee to whom the conveyance shall be made (if other
than to the Lessee), in which case such conveyance shall (subject to the terms
and conditions set forth herein) be made to such designee; provided, however,
that such designation of a transferee shall not cause the Lessee to be
released, fully or partially, from any of its obligations under this Lease.

                  (c) Acceleration of Purchase Obligation. Notwithstanding any
thing contained hereinabove to the contrary, Lessor shall have right, in
Lessor's sole and absolute discretion, to require Lessee to purchase the
Lessor's right, title and interest in the Property immediately, automatically
and without notice upon the occurrence of any Event of Default for the
purchase price set forth in subparagraph (d) below.

                  (d) Determination of Purchase Price. Upon the purchase by
the Lessee of the Lessor's right, title and interest in the Property upon the
exercise of the Purchase Option or pursuant to subparagraphs (b) or (c) above,
the aggregate purchase price for the Property shall be an amount equal to the
Lease Balance as of the closing date for such purchase.

                  (e) Purchase Procedure.

                           (i)      If the Lessee shall purchase the Lessor's
         right, title and interest in the Property pursuant to any provision
         of this Lease, (A) the Lessee shall accept from the Lessor, and the
         Lessor shall convey or cause Issuer to convey, the Property by a duly
         executed and acknowledged special warranty deed in recordable form,
         (B) upon the date fixed for any purchase of the Lessor's right, title
         and interest in the Property hereunder, the Lessee shall pay to the
         order of the Agent the Lease Balance, by wire transfer of immediately
         available federal funds, and (C) the Lessor will execute and deliver
         or cause Issuer to execute and deliver to the Lessee such other
         documents, including releases, affidavits, termination agreements and
         termination statements, as may be legally required or as may be
         reasonably requested by the Lessee in order to effect such
         conveyance, free and clear of the lien of the Deed of Trust and any
         Encumbrances created by Lessor.

                           (ii)     The Lessee shall, at the Lessee's sole
         cost and expense, obtain all required governmental and regulatory
         approvals and consents and, in connection therewith, shall make such
         filings as required by Law. In the event that the Lessor is required
         by Law to take any action in connection with such purchase and sale,
         the Lessee shall pay prior to transfer all costs incurred by the
         Lessor in connection therewith.  Without limiting the foregoing, all
         costs incident to such conveyance, including, without limitation, the
         Lessee's attorneys' fees, the Lessor's attorneys' fees, Issuer's
         attorneys' fees, the fees of the Credit Facility Providers, the fees
         of the Trustee, the costs incurred in connection with the purchase
         and sale pursuant to the Operative Documents, commissions, the
         Lessee's, the Lessor's and Issuer's escrow fees, recording fees,
         title insurance premiums and all applicable documentary transfer or
         other transfer taxes and other taxes required to be paid in order to
         record the transfer documents that might be imposed by reason of such
         conveyance and the delivery of such deed shall be borne entirely by
         and paid by the Lessee.

                                      33

<PAGE>

                           (iii)    Upon expiration or termination of this
         Lease resulting in conveyance of the Lessor's right, title and
         interest in the Property to the Lessee, there shall be no
         apportionment of rents (including, without limitation, water rents
         and sewer rents), taxes, insurance, utility charges or other charges
         payable with respect to the Property, all of such rents, taxes,
         insurance, utility charges or other charges due and payable with
         respect to the Property prior to termination being payable by the
         Lessee hereunder and all due after such time being payable by the
         Lessee as the then owner of the Property.

                  (f) Option to Remarket. Subject to the fulfillment of each
of the conditions set forth in this subparagraph (f), the Lessee shall have
the option to market all (but not less than all) of the Property for the
Lessor (the "Remarketing Option"). The Lessee's effective exercise and
consummation of the Remarketing Option shall be subject to the due and timely
fulfillment of each of the following provisions, the failure of any of which,
unless waived in writing by the Lessor and the Agent, shall render the
Remarketing Option and the Lessee's exercise thereof null and void, in which
event, the Lessee shall be obligated to perform its obligations under
subparagraph (b) above:

                           (i)      Not later than twelve (12) months prior to
         the Expiration Date, the Lessee shall give to the Lessor and the
         Agent written notice of the Lessee's exercise of the Remarketing
         Option.

                           (ii)     Not later than ten (10) Business Days
         prior to the Expiration Date, the Lessee shall deliver to the Lessor
         and the Agent an environmental assessment of the Property dated not
         earlier than forty-five (45) days prior to the Expiration Date. Such
         environmental assessment shall be prepared by an environmental
         consultant selected by the Agent, shall be in form, detail and
         substance reasonably satisfactory to the Agent and shall otherwise
         indicate the environmental condition of the Property to be the same
         as described in the Environmental Audit.

                           (iii)    On the date of the Lessee's notice to the
         Lessor and the Agent of the Lessee's exercise of the Remarketing
         Option, no Event of Default shall exist, and thereafter, no Event of
         Default shall exist under this Lease.

                           (iv)     At the time of exercise and as of the date
         of closing, the Lessee shall have completed all Alterations,
         restoration and rebuilding of the Property leased by it pursuant to
         Paragraphs 12 and 13 (as the case may be) and shall have fulfilled
         all of the conditions and requirements in connection therewith
         pursuant to such Paragraphs or otherwise as required hereunder or
         under the Deed of Trust or any of the other Operative Documents, in
         each case, by the date on which the Lessor and the Agent receive the
         Lessee's notice of the Lessee's exercise of the Remarketing Option
         (time being of the essence), regardless of whether the same shall be
         within the Lessee's control.  If any use of the Property has
         substantially changed the character of the Property (without implying
         any consent to such use by the Lessor or the Agent), the Lessee
         shall, if requested by the Lessor or the Agent, restore the Property
         to its general character as of the Commencement Date, except for
         Alterations permitted hereunder and normal wear and tear.

                                      34

<PAGE>

                           (v)      The Lessee shall promptly provide any
         maintenance records relating to the Property to the Lessor, the Agent
         and any potential purchaser upon request and shall otherwise do all
         things necessary to deliver possession of the Property to the
         potential purchaser. The Lessee shall allow the Lessor, the Agent and
         any potential purchaser access to the Property for the purpose of
         inspecting the same.

                           (vi)     On the Expiration Date, the Lessee shall
         surrender the Property leased by it in accordance with subparagraph
         (h) below.

                           (vii)    In connection with any such sale of the
         Property, the Lessee will provide to the purchaser all customary
         "seller's" indemnities requested by the potential purchaser,
         representations and warranties regarding title, absence of liens and
         the condition of the Property, including, without limitation, a
         customary environmental indemnity. The Lessee shall fulfill all of
         the requirements set forth in clause (ii) of subparagraph (e), and
         such requirements are incorporated herein by reference. As to the
         Lessor and Issuer, any such sale shall be made on an "as is, where
         is, with all faults" basis without representation or warranty by the
         Lessor or Issuer.

                           (viii)   In connection with any such sale of the
         Property, the Lessee shall pay directly, and not from the sale
         proceeds, all prorations, credits, costs and expenses of the sale of
         the Property leased by it, whether incurred by the Lessor, Issuer,
         any Credit Facility Provider, the Agent or the Lessee, including
         without limitation, the cost of all title insurance, surveys,
         environmental reports, appraisals, transfer taxes, the Lessor's,
         Issuer's, any Credit Facility Provider's and the Agent's attorneys'
         fees, the Lessee's attorneys' fees, commissions, escrow fees,
         recording fees and all applicable documentary and other transfer
         taxes.

                           (ix)     The Lessee shall pay to the Agent on the
         Expiration Date (or to such other Person as the Agent shall notify
         the Lessee in writing, or in the case of Additional Rent, to the
         Person entitled thereto) an amount equal to the Residual Guaranty
         Amount, plus all accrued and unpaid Basic Rent and Additional Rent,
         and all other amounts hereunder which have accrued prior to or as of
         such date, by wire transfer of immediately available funds.

         If the Lessee has exercised the Remarketing Option, the following
additional provisions shall apply: During the period commencing on the date
twelve (12) months prior to the scheduled expiration of the Term, the Lessee
shall, as nonexclusive agent for the Lessor, use commercially reasonable
efforts to sell the Lessor's right, title and interest in the Property and
will attempt to obtain the highest purchase price therefor. All such marketing
of the Property shall be at the Lessee's sole expense. Lessee promptly shall
submit all bids to the Lessor and the Agent, and the Lessor and the Agent will
have the right to review the same and the right to submit any one or more
bids. All bids shall be on an all-cash basis. In no event shall such bidder be
the Lessee or any Subsidiary of the Lessee or any affiliate controlled by or
under common control with the Lessee or any subsidiary of the Lessee. The
written offer must specify the Expiration Date as the closing date. If, and
only if, the aggregate selling price (net of closing costs and prorations, as
reasonably estimated by the Agent) plus the Residual Guaranty Amount are less
than the Lease Balance at such time, then the Lessor or the Agent may, in its
sole and

                                      35

<PAGE>

absolute discretion, by notice to the Lessee, reject such offer to purchase,
in which event the parties will proceed according to the provisions of
subparagraph (g) below. If neither the Lessor nor the Agent rejects such
purchase offer as provided above, the closing of such purchase of the Property
by such purchaser shall occur on the Expiration Date, contemporaneously with
the Lessee's surrender of the Property in accordance with subparagraph (h)
below, and the gross proceeds of the sale (i.e., without deduction for any
marketing, closing or other costs, prorations or commissions) shall be paid
directly to the Agent; provided, however, that if the sum of the gross
proceeds from such sale plus the Residual Guaranty Amount paid by the Lessee
on the Expiration Date pursuant to clause (ix) of subparagraph (f), minus any
and all costs and expenses (including broker fees, appraisal costs, legal fees
and transfer taxes) incurred by the Agent or the Lessor in connection with the
marketing of the Property or the sale thereof exceeds the Lease Balance as of
such date, then the excess shall be paid to the Lessee following the
Expiration Date. The Lessee shall not have the right, power or authority to
bind the Lessor or the Agent in connection with any proposed sale of the
Property.

                  (g) Rejection of Sale. Notwithstanding anything contained
herein to the contrary, if the Lessor or the Agent rejects the purchase offer
for the Property as provided in subparagraph (f) above, then (A) the Lessee
shall pay to the Agent the Residual Guaranty Amount pursuant to clause (ix) of
subparagraph (f), (B) the Lessor shall retain title to the Property, and (C)
in addition to the Lessee's other obligations hereunder, the Lessee will
reimburse the Lessor and the Agent, within ten (10) Business Days after
written request, for all reasonable costs and expenses incurred by the Lessor
or the Agent during the period ending on the first anniversary of the
Expiration Date in connection with the marketing, sale, closing or transfer of
the Property, which obligation shall survive the Expiration Date and the
termination or expiration of this Lease.

                  (h) Return of Property. If the Lessor retains title to the
Property pursuant to subparagraph (g) above, then the Lessee shall, on the
Expiration Date, and at its own expense, return possession of the Property to
the Lessor for retention by the Lessor or, if the Lessee properly exercises
the Remarketing Option and fulfills all of the conditions of subparagraph (f)
above and neither the Lessor nor the Agent rejects such purchase offer
pursuant to subparagraph (f) above, then the Lessee shall, on such Expiration
Date, and at its own cost, transfer possession of the Property to the
independent purchaser thereof, in each case by surrendering the same into the
possession of the Lessor or such purchaser, as the case may be, free and clear
of all liens other than the Deed of Trust and other Encumbrances, in as good
condition as it was on the Commencement Date (as modified by Alterations
permitted by this Lease), ordinary wear and tear excepted, and in compliance
with all Laws and all other requirements of this Lease and the Deed of Trust.
The Lessee shall, on and within a reasonable time before and after the
Expiration Date, cooperate with the Lessor and the independent purchaser of
the Property in order to facilitate the ownership and operation by such
purchaser of the Property after the Expiration Date, which cooperation shall
include the following, all of which the Lessee shall do on or before the
Expiration Date: providing all books and records regarding the maintenance and
ownership of the Property and all know-how, data and technical information
relating thereto, granting or assigning all licenses necessary for the
operation and maintenance of the Property and cooperating in seeking and
obtaining all necessary governmental approvals. The Lessee shall have also
paid the cost of all Alterations commenced prior to the Expiration Date. The

                                      36

<PAGE>

obligations of the Lessee under this Paragraph 19 shall survive the expiration
or termination of this Lease.

                  (i) Environmental Report. Upon termination of this Lease,
unless the Lessee shall have exercised the Purchase Option or shall have
exercised the Remarketing Option and complied with subparagraph (f) above, the
Lessee shall deliver, at the Lessee's expense, to the Lessor and the Agent an
environmental assessment of the Property. Such environmental assessment shall
be prepared by an environmental consultant, and shall be in a form, reasonably
satisfactory to the Lessor and the Agent.

         20. Inspection. Lessee shall permit Lessor, Issuer and the Agent, and
each of their respective representatives and agents (collectively, the
"Inspecting Parties") to enter the Property, with two (2) Business Days prior
notice to Lessee and with an escort provided by Lessee, unless (i) a Default
or an Event of Default shall have occurred and be continuing, or (ii) an
emergency exists, in either of which cases, no advance notice shall be
required, without charge therefor and without diminution of the Rent payable
by Lessee, in order to examine and inspect the Property. All examinations and
inspections of the Property shall be made at the expense of the Inspecting
Parties, except that if a Default or an Event of Default has occurred, Lessee
shall reimburse the Inspecting Parties for the reasonable costs of such
examinations and inspections. Except in the case of an emergency or the
occurrence of a Default or an Event of Default, in connection with any such
entry, Lessor, Issuer and the Agent shall endeavor to minimize the disruption
to Lessee's normal business operations in the Property. None of the Inspecting
Parties shall have any duty to make any such examinations or inspections of
the Property. None of the Inspecting Parties shall incur any liability or
obligation by reason of making any such examination or inspection unless and
to the extent such Inspecting Party causes damage to any Person or to the
Property or any property of Lessee or any other Person during the course of
such examination or inspection.

         21. Notices, Demands and Other Instruments. All notices, demands,
requests, consents, approvals, certificates or other communications required
under this Lease shall be in writing, and shall be sufficiently given and
shall be deemed to have been properly given (i) if delivered by hand, when
written confirmation of delivery is received by the sender, (ii) three days
after the same is mailed by certified mail, postage prepaid, return receipt
requested, or (iii) if sent by overnight courier, 24 hours (plus 24 hours for
any intervening day that is not a Business Day) after delivery to such
overnight courier addressed to the Person to whom any such notice, demand,
request, consent, approval, certificate or other communication is to be given,
at the appropriate address designated on Exhibit D attached hereto. Any party
listed on Exhibit D shall each have the right from time to time to specify as
its address for purposes of this Lease any other address in the United States
of America upon giving ten (10) days' prior written notice hereunder.

         22. Estoppel Certificates. Lessee shall, at any time and from time to
time, upon not less than thirty (30) days' prior written notice from Lessor or
Agent, execute, acknowledge and deliver to the requesting party a statement in
writing, executed by the President or a Vice President of Lessee certifying
(i) that this Lease is unmodified and in full effect (or, if there have been
modifications, that this Lease is in full effect as modified, and setting
forth such modifications), (ii) the dates to which Basic Rent, Additional Rent
and all other sums payable

                                      37

<PAGE>

hereunder have been paid, (iii) that to the knowledge of the signer of such
certificate no default by Lessor exists hereunder or specifying each such
default of which the signer may have knowledge; and (iv) to the knowledge of
the signer of such certificate, there are no proceedings pending or threatened
against Lessee before or by any court or administrative agency which, if
adversely decided, would materially and adversely affect the financial
condition and operations of Lessee or Lessee's ability to perform or fulfill
its obligations under this Lease, or if any such proceedings are pending or
threatened to said signer's knowledge, specifying and describing the same. It
is intended that any such statements may be relied upon by the Credit Facility
Providers, Agent, Lessor, Issuer or their assignees or by any prospective
purchaser of the Property.

         23. No Merger. There shall be no merger of this Lease or of the
leasehold estate hereby created by reason of the fact that the same Person may
acquire, own or hold, directly or indirectly, in whole or in part, (a) any
interest in this Lease or the leasehold estate hereby created, (b) title to or
any other interest in the Property or any part thereof or (c) a beneficial
interest in Lessor.

         24. Representations and Warranties of Lessee.  Lessee makes the
following representations and warranties to Lessor:

                  (a) Good Standing. Lessee (i) is a corporation duly
organized and existing, in good standing, under the laws of the State of
Delaware, (ii) has the corporate power and all material governmental licenses,
authorizations, consents and approvals required to own its property and to
carry on its business as now being conducted, and (iii) is duly qualified to
do business and is in good standing in each jurisdiction in which the
character of the properties owned by it therein or in which the transaction of
its business makes such qualification necessary, including, but not limited
to, the State of Maryland.

                  (b) Authority. Lessee has full corporate power and authority
to enter into and execute and deliver this Lease and each of the other
Operative Documents to which Lessee is a party, and to incur and perform the
obligations provided for therein and herein, all of which have been duly
authorized by all proper and necessary corporate action by Lessee. No consent
or approval of stockholders or of any other Person or public authority or
regulatory body is required as a condition to the validity or enforceability
of this Lease or any of the other Operative Documents, or if required the same
has been duly obtained.

                  (c) Binding Agreements. This Lease and each of the other
Operative Documents to which Lessee is a party have been duly and properly
executed by Lessee, constitute the valid and legally binding obligations of
the Lessee, and are fully enforceable against Lessee in accordance with their
respective terms, except to the extent that enforceability may be affected by
any bankruptcy or insolvency proceeding filed by or against the Lessee and
subject to the exercise of judicial discretion in accordance with general
principles of equity.

                  (d) Litigation. There is no litigation or proceeding pending
or, to the best of Lessee's knowledge, threatened, before any court or
administrative agency which, in the opinion of Lessee, will materially
adversely affect the financial condition or operations of Lessee, Lessee's
ability to perform and fulfill its obligations under this Lease or any of the
other

                                      38

<PAGE>

Operative Documents, or the authority of Lessee to enter into, or the validity
or enforceability of, this Lease or any of the other Operative Documents.

                  (e) No Conflicting Agreements, Laws, etc. There is (i) no
charter, by-law or preference stock provision of Lessee and no provision of
any existing mortgage, indenture, contract or agreement binding on Lessee or
affecting Lessee's property, and (ii) to the knowledge of Lessee, no provision
of Law or order of court binding on Lessee or affecting any of Lessee's
property, which would conflict with or in any way prevent the execution,
delivery, or performance of the terms of this Lease or any of the other
Operative Documents, or which would be in default or violated as a result of
such execution, delivery or performance, or for which adequate consents or
waivers have not been obtained.

                  (f) Tax Returns. Lessee has either (i) filed all required
federal, state and local tax returns and has paid all taxes as shown on such
returns as they have become due or (ii) filed for an extension of the filing
date for such returns and the date by which any such taxes must be paid. No
claims have been assessed and are unpaid with respect to such taxes, and
Lessee has established reserves which it believes to be adequate for the
payment of any taxes for which an extension has been properly filed and for
the payment of additional taxes for years which have not been audited by the
respective tax authorities.

                  (g) Place of Business of Lessee.  Lessee's principal place
of business is located at 9410 Key West Avenue, Rockville, Maryland 20850.

                  (h) Brokers. To the best of Lessee's knowledge, no Person
has, or as a result of any action of or by Lessee in connection with the
transactions contemplated hereby and by the Lease will have, any right,
interest or valid claim against or on Lessor for any commission, fee or other
compensation as a broker or finder, or in any similar capacity. Lessee shall
indemnify Lessor against any claimed fee, commission or other compensation
arising from or in connection with the transactions contemplated hereby or by
the other Operative Documents.

                  (i) ERISA. (i) Each Plan satisfies the qualification
requirements under Section 401 of the Code, both in form and in operation, and
there is no current matter which would materially adversely affect the tax
qualified status of any Plan; (ii) neither the Lessee nor any Commonly
Controlled Entity has engaged in or is engaging in any Prohibited Transaction,
unless such transaction is exempt from the restrictions imposed by Section 406
of ERISA and Section 4975 of the Code; (iii) there is no Accumulated Funding
Deficiency, whether or not waived, with respect to any Plan; (iv) no
Reportable Events have occurred with respect to any Plan subject to Title IV
of ERISA (other than those Reportable Events for which notice has been waived
pursuant to regulations issued under Section 4043 of ERISA); (v) neither the
Lessee nor any Commonly Controlled Entity has filed an application for a
waiver of the minimum funding standard with respect to any Plan; (vi) neither
the Lessee nor any Commonly Controlled Entity has incurred any liability under
Title IV of ERISA with respect to the termination of any Plan, (vii) neither
the Lessee nor any Commonly Controlled Entity has "withdrawn" or "partially
withdrawn" from any Multiemployer Plan; and (viii) no Multiemployer Plan is in
"reorganization" nor has notice been received from the administrator of any
Multiemployer Plan that any such plan will be placed in "reorganization".

                                      39

<PAGE>

         25. Affirmative Covenants of Lessee.

                  (a) Reporting Requirements. Lessee shall furnish or cause to
be furnished to Lessor and the Agent:

                           (i)      as soon as available but in no event more
         than forty-five (45) days after the close of each fiscal quarter of
         Lessee, a copy of the 10Q Report of Lessee filed with the Securities
         and Exchange Commission (the "SEC") accompanied by a certificate of
         the chief financial officer of Lessee stating whether any event has
         occurred which constitutes a Default or an Event of Default, and, if
         so, stating the facts with respect thereto; and

                           (ii)     as soon as available but in no event more
         than ninety (90) days after the close of each fiscal year of Lessee,
         a copy of the 10K Report of Lessee filed with the SEC and a copy of
         the annual audited financial statements relating to Lessee prepared
         in accordance with GAAP, which financial statements shall include a
         balance sheet of Lessee as of the end of such fiscal year and a
         statement of earnings and changes in stockholder's equity of Lessee
         for such fiscal year; and

                           (iii)    as soon as available but in no event more
         than ninety (90) days after the close of each fiscal year of Lessee,
         a certificate of the chief financial officer of Lessee stating
         whether any event which constitutes a Default or an Event of Default
         under this Lease has occurred, and, if so, stating the facts with
         respect thereto; and

                           (iv)     promptly upon transmission thereof, copies
         of any financial statements, proxy statements, reports and the like
         which Lessee sends to its shareholders and copies of all registration
         statements (with exhibits); and

                           (v)      promptly upon the occurrence thereof,
         written notice of any Change in Control; and

                           (vi)     with reasonable promptness, such budgets,
         cash flow projections and other additional information, reports or
         statements as Lessor or the Agent may from time to time reasonably
         request.

                  (b) Taxes and Claims. Pay and discharge or cause to be paid
and discharged all Taxes imposed upon it or its income or properties prior to
the due date thereof, and all lawful claims which, if unpaid, might become a
lien or charge upon any of its properties. Lessee shall have the right to
contest the validity of any such tax, assessment, charge, levy or claim, by
timely and appropriate proceedings, provided that Lessee shall (1) give Lessor
and the Agent written notice of its intention to contest, (2) diligently
prosecute such contest, (3) to the extent such taxes or claims relate to the
Property, fully comply with the provisions of Paragraph 16 hereof, and (4)
establish adequate reserves for such liabilities in accordance with GAAP.

                  (c) Insurance. In addition to the insurance required by
Paragraph 14 of this Lease, maintain insurance with responsible insurance
companies on such of its properties, in such amounts and against such risks as
is customarily maintained by similar businesses operating in the same
vicinity. Lessee shall file with Lessor and the Agent, upon its request, a
detailed list

                                      40

<PAGE>

of the insurance then in effect covering Lessee and Lessee's properties,
stating the names of the insurance companies, the amounts and rates of the
insurance, dates of the expiration thereof and the properties and risks
covered thereby; and, within thirty (30) days after notice in writing from
Lessor and/or the Agent, obtain such additional insurance as Lessor and/or the
Agent may reasonably request.

                  (d) Corporate Existence.  Maintain its existence in good
standing as a Delaware corporation, qualified to transact business in the
State of Maryland.

                  (e) Compliance with Laws. Comply with all Legal
Requirements, subject to Lessee's right to contest the validity or
applicability of any of the foregoing, at its sole cost and expense, in good
faith and by appropriate and diligent proceedings, in accordance with
Paragraph 16 hereof.

                  (f) Books and Records. Maintain appropriate books and
records with respect to the Property and permit access by Lessor and the Agent
and each of their respective authorized representatives and employees to the
books and records of Lessee at the offices of Lessee during normal business
hours.

                  (g) Financial Covenants. Subject to the further terms and
conditions set forth in this Paragraph 25(g), maintain, at all times,
unrestricted cash and securities constituting Permitted Investments (exclusive
of any unrestricted cash or securities maintained by a consolidated subsidiary
of Lessee, but inclusive of securities in the approximate principal amount of
$11,000,000 previously pledged by Lessee to the Bank) with a market value of
at least $75,000,000.

                           (i)      The cash and/or marketable securities
         pledged by Lessee pursuant to the Collateral Pledge Agreement shall
         not be credited against the foregoing $75,000,000 requirement.

                           (ii)     In the event that the market value of such
         unrestricted cash and securities falls below $75,000,000, Lessee
         shall, within two (2) Business Days, pledge to the Agent, as security
         for Lessee's obligations under this Lease and the other Operative
         Documents, in addition to the pledge described in the Collateral
         Pledge Agreement, cash and/or marketable securities constituting
         Permitted Investments with a market value at all times equal to at
         least $5,000,000.

                           (iii)    Any cash and/or marketable securities
         pledged hereunder shall be held by the Agent in accordance with the
         same terms and conditions as set forth in the Collateral Pledge
         Agreement.

                           (iv)     Lessee shall, within two (2) Business
         Days, deposit with the Agent, additional cash and/or marketable
         securities constituting Permitted Investments whenever the market
         value of each additional pledge hereunder falls below $5,000,000 to
         make up the deficiency.

                           (v)      Whenever the market value of any cash
         and/or marketable securities pledged to the Agent pursuant to clause
         (ii) or clause (iv) above exceeds

                                      41

<PAGE>

         $5,000,000, the Credit Facility Providers shall, in accordance with
         the terms of the Collateral Pledge Agreement, release from the pledge
         cash and/or marketable securities equal to such excess.

                           (vi)     Any investment earnings on the cash and/or
         marketable securities pledged by Lessee pursuant to clause (ii) or
         clause (iv) above shall be distributed quarterly by the Agent to
         Lessee.

                           (vii)    If Lessee pledges cash and/or marketable
         securities to the Agent to satisfy the requirements of clause (ii)
         above and thereafter for a period of two consecutive fiscal quarters
         Lessee returns to compliance with the requirements which necessitated
         such pledge, the Agent shall release such cash and/or marketable
         securities from such pledge. By way of illustration, if the market
         value of Lessee's unrestricted cash and securities (as calculated
         pursuant to clause (ii) or clause (iv) above) falls below $75,000,000
         and Lessee has pledged $5,000,000 of cash and/or marketable
         securities to the Agent and thereafter the market value of Lessee's
         unrestricted cash and securities is greater than $75,000,000 for two
         consecutive fiscal quarters, the Agent shall release from such pledge
         $5,000,000 of cash and/or marketable securities.

                  (h) Appraisal. The Agent, on behalf of the Credit Facility
Providers, shall have the right, in the Agent's reasonable discretion, to
obtain a re-appraisal of the Property upon the occurrence of an Event of
Default or if such re-appraisal is mandated by FIRREA or any other banking or
similar regulation applicable to the Credit Facility Providers. If any such
re-appraisal indicates that the Fair Market Value of the Property has declined
below $30,000,000, the Agent shall have the right to require that the Lessee
provide additional collateral to the Agent to satisfy the Credit Facility
Providers' margin requirements and to otherwise secure the Lessee's
obligations under this Lease and the other Operative Documents, such
additional collateral to be acceptable to the Agent in its sole and absolute
discretion.

         26. Negative Covenants of Lessee. Until all of Lessee's obligations
under this Lease have been paid and performed in full (other than any
indemnities which survive the termination of this Lease), without the prior
written consent of Lessor and the Agent, Lessee shall not, directly or
indirectly:

                  (a) Declare any dividends (other than dividends payable in
capital stock of Lessee) on any shares of any class of its capital stock
(other than preferred stock outstanding on the Commencement Date) or apply any
of its property or assets to the purchase, redemption or other retirement of,
or set apart any sum for the payment of any dividends on, or for the purchase,
redemption or other retirement of, or make any other distribution by reduction
of capital or otherwise in respect of, any shares of any class of capital
stock of Lessee unless (i) there is no Event of Default which has occurred and
is continuing, and (ii) the amount of the dividend does not exceed Lessee's
accumulated earnings at that time.

                  (b) Fail to notify Lessor and the Agent of any change in the
officers (within the meaning of Section 240.16a-1 of the Regulations under the
Securities Exchange Act of 1934, as amended) of Lessee.

                                      42

<PAGE>

                  (c) (i) Restate or amend any Plan in a manner designed to
jeopardize the tax qualified status of such Plan; (ii) permit any officers of
Lessee or any Commonly Controlled Entity to materially adversely affect the
tax qualified status of any Plan; (iii) engage in or permit any Commonly
Controlled Entity to engage in any Prohibited Transaction, unless such
transaction is exempt from the restrictions imposed by Section 406 of ERISA
and Section 4975 of the Code; (iv) permit an Accumulated Funding Deficiency,
whether or not waived, with respect to any Plan; (v) take or permit any
Commonly Controlled Entity to take any action or fail to take any action which
causes a termination of any Plan in a manner which could result in the Lessee
or any Commonly Controlled Entity incurring liability under Title IV of ERISA;
(vi) incur or permit any Commonly Controlled Entity to incur a "complete
withdrawal" or "partial withdrawal" (as defined in Title IV of ERISA) from any
Multiemployer Plan; or (vii) fail to notify the Agent that notice has been
received from the administrator of any Multiemployer Plan to which Lessee or
any Commonly Controlled Entity has an obligation to contribute that any such
Plan will be placed in "reorganization".

                  (d) Amend or otherwise modify the terms and conditions of
the Invitrogen Sublease.

         27. [INTENTIONALLY RESERVED.]

         28. Separability. Each and every covenant and agreement contained in
this Lease is, and shall be construed to be, a separate and independent
covenant and agreement, and the breach of any such covenant or agreement by
Lessor shall not discharge or relieve Lessee from any of its obligations under
this Lease. If any term or provision of this Lease or the application thereof
to any Person or circumstances shall to any extent be invalid and
unenforceable, the remainder of this Lease, or the application of such term or
provision to persons or circumstances other than those as to which it is
invalid or unenforceable, shall not be affected thereby, and each term and
provision of this Lease shall be valid and shall be enforced to the extent
permitted by Law.

         29. Subordination

                  (a) This Lease is subject and subordinate to the Head Lease
and to the lien, provisions, operation and effect of the Deed of Trust and
other Encumbrances now or hereafter encumbering the Property or any interest
therein, to all funds and indebtedness intended to be secured thereby, and to
all renewals, extensions, modifications, recastings or refinancings thereof.
The holder of any Encumbrance to which this Lease is subordinate shall have
the right (subject to any required approval of the holders of any superior
Encumbrance) at any time to declare this Lease to be superior to the lien,
provisions, operation and effect of such Encumbrance, and Lessee shall
execute, acknowledge and deliver all documents required by such holder in
confirmation thereof.

                  (b) Lessee shall, at Lessor's request, promptly execute any
requisite or appropriate document confirming such subordination. Lessee waives
the provisions of any Law now or hereinafter in effect which may give or
purport to give Lessee any right to terminate or otherwise adversely affect
this Lease and Lessee's obligations hereunder in the event any foreclosure
proceeding is prosecuted or completed or in the event the Property or Lessor's
interest therein is transferred by foreclosure, by deed in lieu of foreclosure
or otherwise. At the

                                      43

<PAGE>

request of such transferee, Lessee shall attorn to such transferee and shall
recognize such transferee as the Lessor under this Lease. Lessee agrees that
upon any such attornment, such transferee shall not be (i) bound by any
payment of Basic Rent or Additional Rent made more than one month in advance,
except prepayments in the nature of security for the performance by Lessee of
its obligations under this Lease, but only to the extent such prepayments have
been delivered to such transferee, (ii) bound by any amendment of this Lease
made without the consent of the holder of each Encumbrance existing as of the
date of such amendment, (iii) liable for damages for any breach, act or
omission of any prior Lessor, or (iv) subject to any offsets or defenses which
Lessee might have against any prior Lessor; provided, however, that after
succeeding to Lessor's interest under this Lease, such transferee shall agree
to perform in accordance with the terms of this Lease all obligations of
Lessor arising after the date of transfer. Within five (5) days after the
request of such transferee, Lessee shall execute, acknowledge and deliver any
requisite or appropriate document submitted to Lessee confirming such
attornment.

                  (c) If any prospective or current holder of an Encumbrance
requires that modifications to this Lease be obtained, and provided that such
modifications (i) are reasonable, (ii) do not adversely affect in a material
manner Lessee's use of the Property for the Permitted Use, (iii) do not
increase the rent and other sums to be paid by Lessee, (iv) do not change
Lessee's affirmative or negative covenants set forth herein, or (v) affect
Lessee's Purchase Option, then Lessor may submit to Lessee an amendment to
this Lease incorporating such required modifications, and Lessee shall
execute, acknowledge and deliver such amendment to Lessor within five (5) days
after Lessee's receipt thereof.

         30. Binding Effect. All of the covenants, conditions and obligations
contained in this Lease shall be binding upon and inure to the benefit of the
respective successors and assigns of Lessor and Lessee to the same extent as
if each successor and assign were in each case named as a party to this Lease.
This Lease may not be changed, modified or discharged except by a writing
signed by Lessor and Lessee and consented to by the Agent.

         31. Headings.  The headings to the various paragraphs of this Lease
have been inserted for convenient reference only and shall not to any extent
have the effect of modifying, amending or changing the expressed terms and
provisions of this Lease.

         32. Environmental Matters.

                  (a) As used in this Paragraph 32, the following items shall
have meanings set forth below:

                           (i)      "CAA" shall mean the Clean Air Act,
         codified at 42 U.S.C. Sections 7401, et seq., as amended.

                           (ii)     "CERCLA" shall mean the Comprehensive
         Environmental Response, Compensation and Liability Act of 1980,
         codified at 42 U.S.C. Sections 9601, et seq., as amended.

                           (iii)    "CWA" shall mean the Clean Water Act,
         codified at 33 U.S.C. 1251; et seq., as amended.

                                      44

<PAGE>

                           (iv)     "Environmental Laws" shall mean CERCLA,
         HMTA, RCRA, CAA, CWA, TSCA, RHA and the Right-to-Know Act and all
         other federal, state, local and municipal laws, statutes, ordinances
         and codes, guidelines and standards relating to health, safety,
         sanitation, and the protection of the environment or governing the
         use, storage, treatment, generation, transportation, processing,
         handling, production or disposal of Hazardous Materials, including,
         without limitation, laws and regulations regarding the discharge of
         water or other materials or fluids into waterways, and the rules,
         regulations, guidelines, decisions, orders and directives of federal,
         state, local and municipal governmental agencies, authorities and
         courts with respect thereto presently in effect or hereafter enacted,
         promulgated or implemented.

                           (v)      "Environmental Permits" shall mean all
         permits, licenses, approvals, authorizations, consents or
         registrations required by any applicable Environmental Laws, on
         either an individual or group basis, in connection with the
         ownership, use or operation of the Property, or the storage,
         treatment, generation, transportation, processing, handling,
         production or disposal of Hazardous Materials related to or generated
         at the Property.

                           (vi)     "Hazardous Materials" shall mean, without
         limitation, flammables, explosives, radioactive materials, asbestos,
         urea formaldehyde foam insulation, polychlorinated biphenyls,
         petroleum or petroleum based or related substances, hydrocarbons or
         like substances and their additives or constituents, and any
         substances now or hereafter defined as "hazardous substances,"
         "extremely hazardous substances," "hazardous materials," "controlled
         hazardous substances," "hazardous wastes" or "toxic chemicals" in
         CERCLA, HMTA, RCRA, CAA, CWA, TSCA, RHA, the Right-To-Know Act, or
         any so-called "superfund" or "superlien" law or the regulations
         promulgated pursuant thereto, or any other applicable federal, state
         or local law, common law, code, rule, regulation, order, or
         ordinance, presently in effect or hereafter enacted, promulgated or
         implemented.

                           (vii)    "HMTA" shall mean the Hazardous Materials
         Transportation Act, codified at 49 U.S.C. Sections 1801, et seq., as
         amended.

                           (viii)   "RCRA" shall mean the Resource
         Conservation and Recovery Act of 1976, codified at 42 U.S.C. Sections
         6901, et seq., as amended.

                           (ix)     "Release" shall have the same meaning as
         given to that term in CERCLA, as amended, and the regulations
         promulgated thereunder.

                           (x)      "RHA" shall mean the Rivers and Harbors
         Appropriation Acts, codified at 33 U.S.C. Sections 401, et seq., as
         amended.

                           (xi)     "Right-To-Know Act" shall mean the
         Emergency Planning and Community Right-To-Know Act, codified at 42
         U.S.C. Sections 11001, et seq., as amended.

                           (xii)    "TSCA" shall mean the Toxic Substances
         Control Act, codified at 15 U.S.C. Sections 2601, et seq., as
         amended.

                                      45

<PAGE>

                  (b) Lessee shall comply at all times and in all respects
with the provisions of all Environmental Laws and Environmental Permits, and
shall not commit any actions or omissions that result in the incurrence of any
liability under such Environmental Laws or Environmental Permits. Lessee will
not allow, cause or permit any Hazardous Materials to be deposited on or under
the Property, or otherwise Released or threatened to be Released from or on
the Property by any Person whatsoever except as normally and properly used in
the operation of the Property in compliance with all Environmental Laws.
Lessee shall conduct all of its activities on the Property, including, without
limitation, the off-site disposal of any Hazardous Materials originating on or
from the Property, in compliance with all Environmental Laws. Lessee shall
obtain, whenever necessary and in its own name, appropriate Environmental
Permits for its operations and shall comply in all respects with the
requirements of such Environmental Permits.

                  (c) Lessee hereby agrees to indemnify, hold harmless and
defend Lessor, Issuer, the Agent, the Certificate Holder, and the Credit
Facility Providers, and their partners, officers, directors, lenders, agents
and employees from and against any and all claims, losses, damages,
liabilities, penalties, costs, assessments, expenses, demands, fines or
liabilities of whatever kind or nature, including, without limitation, costs,
expenses (including expense of posting a bond) and liabilities imposed upon
Lessor pursuant to any indenture or other document, in any way relating to or
arising out of:

                           (i)      The Release or threat of Release of any
         Hazardous Materials in, on, above, from or under the Property during
         the Term hereof;

                           (ii)     Any activity by any party on, off or
         within the Property in connection with the use, handling, treatment,
         monitoring, removal, storage, decontamination, clean up, testing,
         transportation or disposal of any Hazardous Materials located at any
         time on, within or under the Property and introduced onto the
         Property at any time on or after the Commencement Date and prior to
         the expiration or other termination of this Lease;

                           (iii)    The use, handling, treatment, monitoring,
         removal, storage, decontamination, clean-up, testing, transportation
         or disposal of any Hazardous Materials on, under or within the
         Property which were introduced onto, under or within the Property at
         any time on or after the Commencement Date and prior to the
         expiration or other termination of this Lease;

                           (iv)     The performance by Lessee or any other
         Person acting on behalf of Lessee during the Term of any inspection,
         investigation, audit, study, sampling, testing, removal, containment
         or other remedial action or other clean-up related to Hazardous
         Materials on, above, within, related to, or affected by, the
         Property;

                           (v)      The Imposition, recording or filing of any
         lien (including, without limitation, a so-called "superlien") against
         the Property as a result of the incurrence by any party of any
         claims, expenses, demands, losses, costs, fines or liabilities of
         whatever kind or nature with respect to any actual, suspected or
         threatened Release of Hazardous Materials or environmental condition,
         on, above, within, related to, or affected by, the

                                      46

<PAGE>

         Property at any time after the Commencement Date and prior to the
         expiration or other termination of this Lease; or

                           (vi)     The violation by Lessee of any applicable
         Environmental Laws or Environmental Permits with respect to the
         Property. The provisions of this subparagraph (c) shall survive the
         expiration or any other termination of this Lease.

                  (d) Lessee has obtained a "Phase I" environmental report
prepared by ManTech Environmental Corporation and dated February 26, 2001, as
supplemented by a reliance letter from ManTech Environmental Corporation dated
as of April 27, 2001 (the "Environmental Audit") which does not indicate any
presence of any Hazardous Materials on, above or below the Property (other
than Hazardous Materials used, generated and stored in compliance with
applicable Environmental Laws), or of the Release or threat of Release of any
Hazardous Materials existing prior to the Commencement Date.

                  (e) Unless Lessee exercises its Purchase Option, no less
than nine (9) months prior to the expiration of the Term hereof, Lessee shall
cause to be prepared, by an environmental consultant reasonably acceptable to
Lessor and the Agent, an environmental assessment of the Land and the
Improvements (the "Assessment"), which shall identify the presence or probable
presence of any Hazardous Materials on, above or below the Property (other
than Hazardous Materials used, generated and stored in compliance with
applicable Environmental Laws), or the Release or threat of Release of any
Hazardous Materials or any violation of any Environmental Laws with respect to
the Property or Lessee's operations thereon or therein. To the extent that the
Assessment identifies any such Hazardous Materials, Releases or threatened
Releases or violations, Lessee shall take all such measures, including,
without limitation, any and all such measures as shall be recommended by such
environmental consultant, to remove, remedy and/or cure such condition, so
that, by the end of the Term hereof, no Hazardous Materials shall be present
on, above, within or under the Property (other than Hazardous Materials used,
generated and stored in compliance with applicable Environmental Laws), no
Release or threat of Release of Hazardous Materials exists, and no violation
of Environmental Laws shall exist with respect to the Property or Lessee's
operations thereon or therein. Any such response actions undertaken by Lessee
shall comply fully with all applicable Environmental Laws. If Lessee fails to
provide the Assessment to Lessor and the Agent by the date that is nine (9)
months prior to the expiration of the Term, or fails to take such recommended
measures and to remove any Hazardous Materials and comply with all
Environmental Laws as aforesaid, Lessor and/or the Agent may, but shall not be
obligated to, have such Assessment prepared and such removal and/or remedial
measures undertaken at the expense of Lessee, the costs of which shall be
considered Additional Rent hereunder. The foregoing provisions of this
subparagraph (e) shall survive the expiration or any other termination of this
Lease and shall not be construed to relieve Lessee in any way of its
continuing obligations throughout the Term to comply with the provisions of
subparagraph (b) above.

                  (f) Unless Lessee exercises its Purchase Option, as a
condition of any termination of this Lease, Lessee shall cause to be prepared,
by an environmental consultant reasonably acceptable to Lessor, an Assessment
which shall identify the presence or probable presence of any Hazardous
Materials on, above or below the Property (other than Hazardous Materials
used,

                                      47

<PAGE>

generated and stored in compliance with applicable Environmental Laws), or the
Release or threat of Release of any Hazardous Materials or any violation of
any Environmental Laws with respect to the Property or Lessee's operations
thereon or therein. To the extent that the Assessment identifies any such
Hazardous Materials, Releases or threatened Releases or violations, Lessee
shall take all such measures, including, without limitation, any and all such
measures as shall be recommended by such environmental consultant, to remove,
remedy and/or cure such condition and to remove all Hazardous Materials, so
that, as soon as practicable after the termination of this Lease, no Hazardous
Materials shall be present on, above, within or under the Property, no Release
or threat of Release of Hazardous Materials exists, and no violation of
Environmental Laws shall exist with respect to the Property or Lessee's
operations thereon or therein. Any such response actions undertaken by Lessee
shall comply fully with all applicable Environmental Laws. If Lessee fails to
engage an environmental consultant to provide the Assessment to Lessor and the
Agent within fifteen (15) days of the event which causes or permits
termination of this Lease, or fails to take such recommended measures and to
remove any Hazardous Materials and comply with all Environmental Laws as
aforesaid, Lessor and/or the Agent may, but shall not be obligated to, have
such Assessment prepared and such removal and/or remedial measures undertaken
at the expense of Lessee, the costs of which shall be considered Additional
Rent hereunder. The foregoing provisions of this subparagraph (f) shall
survive the expiration or any other termination of this Lease and shall not be
construed to relieve Lessee in any way of its continuing obligations
throughout the Term to comply with the provisions of subparagraph (b) above.

                  (g) If Lessee fails to comply with the provisions of
subparagraph (e) or subparagraph (f) above within the applicable time frames
provided for therein, without regard to any cure rights herein or in any other
Operative Documents (whether or not Lessor has taken any remedial measures as
provided in subparagraph (e) or subparagraph (f)), Lessee shall be deemed to
have elected to purchase the Property as provided in Paragraph 19 above.

         33. Quiet Enjoyment. So long as no Default or Event of Default exists
hereunder, and subject to the terms of this Lease, the other Operative
Documents and any matters of record, Lessor covenants that it will not
interfere with the quiet enjoyment of the Property by Lessee or any of its
permitted sublessees. Such right of quiet enjoyment is independent of, and
shall not affect, Lessor's rights otherwise to initiate legal action to
enforce the obligations of Lessee under this Lease.

         34. [INTENTIONALLY RESERVED.]

         35. Nature of Transaction. With respect to the Property, it is the
intent of Lessee and the Credit Facility Providers that, (i) for accounting
purposes, this Lease and the transactions contemplated by the Operative
Documents shall be treated as an operating lease, and (ii) for federal, state
and local tax purposes and for bankruptcy, commercial and regulatory law and
all other purposes, this Lease and the transactions contemplated by the
Operative Documents shall be treated as the repayment and security provisions
of a loan by Lessor and the Credit Facility Providers to Lessee, that Lessee
shall be treated as the legal and beneficial owner entitled to any and all
benefits of ownership of such Property and that all payments of Basic Rent and
Lease Balance during the Term shall be treated as payments of interest and, if
applicable, principal. Lessee and Lessor agree to file tax returns consistent
with such intent. Nevertheless, Lessee

                                      48

<PAGE>

acknowledges and agrees that neither Lessor, the Agent nor any Credit Facility
Provider or any other Person has made any representations or warranties
concerning the tax, financial, accounting or legal characteristics or
treatment of the Operative Documents and that Lessee has obtained and relied
solely upon the advice of its own tax, accounting and legal advisors
concerning the Operative Documents and the accounting, tax, financial and
legal consequences of the transactions contemplated therein.

         36. Grant of Lien and Future Assurances.

                  (a) Intent of the Parties. It is the intent of the parties
hereto that this Lease grants a security interest and deed of trust lien, as
the case may be, on the Property and the other Lessee Collateral to and for
the benefit of Lessor (for the benefit of Lessor and the Credit Facility
Providers) to secure Lessee's performance under and payment of all amounts
under this Lease and the other Operative Documents.

                  (b) Transactions to be Regarded as Loans. Specifically,
without limiting the generality of Paragraph 35, Lessor and Lessee intend and
agree that in the event of any insolvency or receivership proceedings or a
petition under the United States bankruptcy laws or any other applicable
insolvency laws or statute of the United States of America or any State or
Commonwealth thereof affecting Lessee, Lessor, any Credit Facility Providers
or any collection actions, the transactions evidenced by the Operative
Documents shall be regarded as loans made by the Lessor and the Credit
Facility Providers as unrelated third party lenders to or for the benefit of
Lessee secured by the Property and the other Lessee Collateral.

                  (c) Mortgage Lien. Specifically, without limiting the
generality of Paragraph 35, Lessee has MORTGAGED, GRANTED, BARGAINED, SOLD,
CONVEYED and CONFIRMED, and does hereby MORTGAGE, GRANT, BARGAIN, SELL, CONVEY
and CONFIRM, a lien on the Property and the other Lessee Collateral to secure
to Lessor (for the benefit of the Credit Facility Providers) (i) all amounts
advanced by Lessor and the Credit Facility Providers pursuant to the terms of
the Operative Documents together with yield or interest, as applicable,
thereon, and all other amounts payable under the Operative Documents in
connection therewith and (ii) all other obligations of Lessee under the
Operative Documents, effective on the date hereof.

                  (d) Security Agreement. Specifically, but without limiting
the generality of Paragraph 35, Lessor and Lessee further intend and agree
that, for the purpose of securing the payment of the above-described amounts
and to further secure all other obligations of Lessee under the Operative
Documents, (i) this Lease and the Lease Supplement shall also be deemed to be
a security agreement and financing statement within the meaning of Article 9
of the Maryland Uniform Commercial Code (it being understood that Lessee
hereby conveys and warrants and grants a security interest in the Property and
the other Lessee Collateral to Lessor (for the benefit of Lessor and the
Credit Facility Providers) to secure all amounts advanced by Lessor and the
Credit Facility Providers pursuant to the terms of the Operative Documents,
together with yield or interest thereon, and all other amounts payable under
the Operative Documents and all other obligations of Lessee under the
Operative Documents); (ii) the possession by Lessor or any of its agents of
notes and such other items of property as constitute instruments, money,
negotiable documents or chattel paper shall be deemed to be "possession by the
secured party" for purposes of perfecting the security interest pursuant to
Section 9-313 of the Maryland Uniform

                                      49

<PAGE>

Commercial Code; and (iii) notifications to Persons holding such property, and
acknowledgments, receipts or confirmations from financial intermediaries,
bankers or agents (as applicable) of Lessee shall be deemed to have been given
for the purpose of perfecting such security interest under any Law. Lessor and
Lessee shall, to the extent consistent with this Lease and the Lease
Supplement, take such actions and execute, deliver, file and record such other
documents, financing statements and mortgages as may be necessary to ensure
that, if the Lease was deemed to create a security interest in the Property
and the other Lessee Collateral in accordance with this Paragraph 36, such
security interest would be deemed to be a first priority perfected security
interest (subject only to the Deed of Trust and Encumbrances) and will be
maintained as such throughout the Term.

                  (e) Deed of Trust. Specifically, but without limiting the
foregoing or the generality of Paragraph 35, Lessee hereby grants, bargains,
sells, warrants, conveys, aliens, remises, releases, assigns, sets over and
confirms to Joseph C. LeMense and J. Scott Ensor (collectively, the "Deed of
Trust Trustees") all of Lessee's right, title, and interest in and to the
following (collectively, the "Mortgaged Property"): (i) the Property and all
appurtenances relating thereto and all proceeds, both cash and noncash
thereof; (ii) all easements, rights-of-way, strips and gores of land, vaults,
streets, ways, alleys, passages, sewer rights, waters, water courses, water
rights, minerals, flowers, shrubs, crops, trees, timber and other emblements,
and all estates, rights, titles, interests, tenements, hereditaments and
appurtenances, reversions and remainders whatsoever, in any way belonging,
relating or appertaining to the Property or any part thereof, whether now
owned or hereafter acquired by Lessee; (iii) all right, title and interest of
Lessee in any and all leases, rental agreements and arrangements of any sort
now or hereafter affecting the Property or any portion thereof and providing
for or resulting in the payment of money to Lessee for the use of the Property
or any portion thereof, whether the user enjoys the Property or any portion
thereof as Lessee for years, licensee, Lessee at sufferance or otherwise, and
irrespective of whether such leases, rental agreements and arrangements be
oral or written, and including any and all extensions, renewals and
modifications thereof (the "Subject Leases") and guaranties of the performance
or obligations of any Lessees or lessees thereunder, together with all income,
rents, issues, profits and revenues from the Subject Leases (including all
Lessee security deposits and all other Lessee deposits, whether held by Lessee
or in a trust account, and all other deposits and escrow funds relating to any
Subject Leases), and all the estate, right, title, interest, property,
possession, claim and demand whatsoever at law, as well as in equity, of
Lessee of, in and to the same; provided, however, that although this Lease
contains (and it is hereby agreed that this Lease contains) a present,
current, unconditional and absolute assignment of all of said income, rents,
issues, profits and revenues, Lessee shall collect and apply such rental
payments and revenues as provided in this Lease and the other Operative
Documents; (iv) all right, title and interest of Lessee in, to and under all
franchise agreements, management contracts, consents, authorizations,
certificates and other rights of every kind and character of any of the
Property, to the extent the same are transferable, service contracts, utility
contracts, leases of equipment, documents and agreements relating to the
construction of the Property (including any and all construction contracts,
architectural contracts, engineering contracts, designs, plans,
specifications, drawings, surveys, tests, reports, bonds and governmental
approvals) and all other contracts, licenses and permits now or hereafter
affecting the Property or any part thereof and all guaranties and warranties
with respect to any of the foregoing (the "Subject Contracts"); (v) all right,
title and interest of Lessee in any insurance policies or binders now or
hereafter relating to the Property, including any unearned premiums thereon,
as further

                                      50

<PAGE>

provided in this Lease; (vi) all right, title and interest of Lessee in any
and all awards, payments, proceeds and the right to receive the same, either
before or after any foreclosure hereunder, as a result of any temporary or
permanent injury or damage to, taking of or decrease in the value of the
Property by reason of casualty, condemnation or otherwise as further provided
in this Lease; (vii) all right, title and interest of Lessee in all utility,
escrow and all other deposits (and all letters of credit, certificates of
deposit, negotiable instruments and other rights and evidence of rights to
cash) now or hereafter relating to the Property or the purchase, construction
or operation thereof; (viii) all claims and causes of action arising from or
otherwise related to any of the foregoing, and all rights and judgments
related to any legal actions in connection with such claims or causes of
action; (ix) all Alterations, extensions, additions, improvements,
betterments, renewals and replacements, substitutions, or proceeds of any of
the foregoing acquired with proceeds of any of the property described
hereinabove; all of which foregoing items are hereby declared and shall be
deemed to be a portion of the security for the indebtedness and obligations
herein described, a portion of the above described collateral being located
upon the Land; and (x) all of the other Lessee Collateral, IN TRUST, HOWEVER,
WITH POWER OF SALE, to secure (i) all amounts advanced by Lessor and the
Credit Facility Providers pursuant to the terms of the Operative Documents
together with Yield or Interest, as applicable, thereon, and all other amounts
payable under the Operative Documents in connection therewith and (ii) all
other obligations of Lessee under the Operative Documents, effective on the
date hereof.

                  (f) Power of Sale Remedies. Without limiting any other
remedies set forth herein, in the event that a court of competent jurisdiction
rules that this Lease constitutes a deed of trust or other secured financing
with respect to the Property as is the intent of the parties pursuant to this
Paragraph 36, then Lessor and Lessee agree that, upon the occurrence and
during the continuance of any Event of Default, the Deed of Trust Trustees
may, and are hereby irrevocably empowered to, with or without entry, and to
the extent permitted by applicable law, sell or cause the sale of the Property
or any part or parts thereof at one or more public auctions as an entirety or
in parcels as Lessor may elect free from any equity of redemption for cash, on
credit, or for other property, for immediate or future delivery, and on such
terms as the Deed of Trust Trustees shall deem advantageous and proper, such
sale or sales to be made in such manner and upon such notice and advertisement
as may be required by applicable law, or in the absence of any such
requirements, as Lessor may deem appropriate, and to make conveyance to the
purchase or purchasers. Notwithstanding the foregoing, upon the occurrence of
an Event of Default, Lessor may, at its option, proceed to foreclose on the
Property by judicial foreclosure.

WAIVER: LESSEE ACKNOWLEDGES AND AGREES THAT IF IT DEFAULTS, A NON-JUDICIAL
FORECLOSURE SALE OF THE PROPERTY, IF PERMITTED BY LAW, MAY BE CONDUCTED
WITHOUT A HEARING OF ANY KIND AND WITHOUT NOTICE BEYOND THE PUBLICATION AND
POSTING OF THE NOTICE OF SALE AS REQUIRED BY LAW. LESSEE HEREBY WAIVES TO THE
EXTENT PERMITTED BY LAW ANY RIGHTS IT MAY HAVE TO ANY SUCH HEARING AND NOTICE.

                  (g) UCC Remedies. In addition to any other remedies granted
in this Lease to Lessor (including specifically, but not limited to, the right
to proceed against the Property in accordance with the rights and remedies in
respect to those portions of the Property which are real property pursuant to
Section 9-604(a) of the Maryland Uniform Commercial Code), Lessor may proceed
under the Maryland Uniform Commercial Code as to all or any part of the
personal property (tangible or intangible) and fixtures included with the
Property (such portion of the

                                      51

<PAGE>

Property being referred to herein as the "Personalty") and shall have and may
exercise with respect to the Personalty all the rights, remedies, and powers
of a secured party under the Maryland Uniform Commercial Code, including,
without limitation, the right and power to sell, at one or more public or
private sales, or otherwise dispose of, lease, or utilize the Personalty and
any part or parts thereof in any manner authorized or permitted under the
Maryland Uniform Commercial Code after default by a debtor, and to apply the
proceeds thereof toward payment of any costs and expenses and attorney's fees
and legal expenses thereby incurred by Lessor, and toward payment of the
indebtedness hereby secured in such order or manner as provided herein. Any
requirement of the Maryland Uniform Commercial Code for reasonable
notification shall be met by mailing written notice to Lessee at its address
set forth in Exhibit D hereto at least ten (10) days prior to the sale or
other event for which such notice is required.

                  (h) Judicial Remedies. Lessor may proceed to protect and
enforce its rights by a suit or suits in equity or at law, or for the specific
performance of any covenant or agreement contained herein or in the Operative
Documents, or in aid of the execution of any power herein or therein granted,
or for the foreclosure of the mortgage lien created by this Lease, or for the
enforcement of any other appropriate legal or equitable remedy and in aid
thereof Lessee hereby assents to the passage of a decree by the equity court
having jurisdiction. Upon the bringing of any suit to foreclose the mortgage
lien created by this Lease or to enforce any other remedy available hereunder,
Lessor shall be entitled as a matter of right, without notice and without
giving bond to Lessee or anyone claiming under, by or through it, and without
regard to the solvency or insolvency of Lessee or the then value of the
premises, to have a receiver appointed of all the Property and of the
earnings, income, rents, issues, profits and proceeds thereof, with such power
as the court making such appointment shall confer, and Lessee does hereby
irrevocably consent to such appointment.

                  (i) Acceleration of Certificates and Payments under the
Letter of Credit Agreement and Other Operative Documents. In case of any sale
of the Property, or of any part thereof, pursuant to any judgment or decree of
any court or otherwise in connection with the enforcement of any of the terms
of this Lease, the principal of the Certificates and all outstanding amounts
due and owing under the Letter of Credit Agreement and the other Operative
Documents, if not previously due, and the Yield and interest accrued thereon,
if any, shall at once become and be immediately due and payable; also in the
case of any such sale, Lessor may bid and become the purchaser, and the
purchaser or purchasers, for the purpose of making settlement for or payment
of the purchase price, shall be entitled to turn in and use the Certificates
and all outstanding amounts due and owing under the Letter of Credit Agreement
and the other Operative Documents, and any claims for Yield and interest due
and unpaid thereon, in order that there may be credited as paid on the
purchase price the sum apportionable and applicable to the Certificates and
all outstanding amounts due and owing under the Letter of Credit Agreement and
the other Operative Documents, including principal, Yield and interest
thereon, out of the net proceeds of such sale after allowing for the
proportion of the total purchase price required to be paid in actual cash. If
at any foreclosure proceeding the Property shall be sold for a sum less than
the total amount of indebtedness for which judgment is therein given, the
judgment creditor shall be entitled to the entry of a deficiency decree
against Lessee and against the property of Lessee for the amount of such
deficiency.

                                      52

<PAGE>

                  (j) Lease Supplement to Control. The provisions of this
Paragraph 36 shall not limit in any manner the specific rights and remedies of
Lessor under the Lease Supplement. Each right, power and remedy provided for
in this Lease or in the Lease Supplement or now or hereafter existing at law
or in equity or by statute or otherwise shall be cumulative and concurrent and
shall be in addition to every other right, power or remedy provided for in
this Lease or now or hereafter existing at law or in equity or by statute or
otherwise, and the exercise or beginning of the exercise of any one or more of
the rights, powers or remedies provided for in this Lease or now or hereafter
existing in law or in equity or by statute or otherwise shall not preclude the
simultaneous or later exercise of any or all other such rights, powers or
remedies. In the event of any conflict or inconsistency between the terms and
provisions of this Lease and the terms and provisions of the Lease Supplement
with respect to the liens, security interests and remedies available to
Lessor, the terms and provisions of the Lease Supplement shall control.

                  (k) Attorney-in-Fact. Lessee hereby irrevocably appoints
Lessor as Lessee's attorney-in-fact, with full authority in the place and
stead of Lessee and in the name of Lessee or otherwise, from time to time in
Lessor's discretion, to execute any instrument which Lessor may deem necessary
or advisable to accomplish the purposes of this Lease (subject to any
limitations set forth in the Operative Documents), and to take any action
(including any action that Lessee is entitled to take), including, without
limitation:

                           (i)      to ask, demand, collect, sue for, recover,
         compromise, receive and give acquittance and receipts for money due
         and to become due under or in connection with all or any portion of
         the Property and the other Lessee Collateral;

                           (ii)     to receive, endorse and collect any drafts
         or other instruments, documents and chattel paper in connection with
         the foregoing clause (a);

                           (iii)    to file any claim or take any action or
         institute any proceedings which Lessor may deem to be necessary or
         advisable for the collection thereof or to enforce compliance with
         the terms and conditions of this Lease; and

                           (iv)     to perform any affirmative obligations of
         Lessee hereunder, including the execution of mortgages, financing
         statements and other documents.

         Lessee hereby acknowledges, consents and agrees that the power of
attorney granted pursuant to this subparagraph (k) is irrevocable and coupled
with an interest. Notwithstanding anything contained herein to the contrary,
the rights and powers presently granted Lessor by this subparagraph (k) may be
exercised by Lessor only upon the occurrence and during the continuance of an
Event of Default.

         37. Miscellaneous.

                  (a) This Lease may be executed in any number of
counterparts, each of which shall be an original, but all of which shall
together constitute one and the same instrument.

                  (b) References to the masculine shall include the feminine
and neuter and the plural shall include the singular, as the context may
require.

                                      53

<PAGE>

                  (c) This Lease shall be construed and enforced in accordance
with the Law of the State of Maryland.

                  (d) Time is of the essence with respect to each and every
provision of this Lease.

                  (e) With respect to any provision of this Lease which
requires Lessor to not unreasonably withhold its consent or approval, if in
connection therewith Lessor is obligated under the Operative Documents to
obtain the consent or approval of Issuer, the Trustee, the Agent, the Credit
Facility Providers or any other third party, then Lessor's failure to provide
consent or failure to otherwise act in a reasonable manner because of its
inability to obtain the consent or approval of Issuer, the Trustee, the Agent,
the Credit Facility Providers or other third party shall not be deemed
unreasonable, so long as Lessor has made a good faith effort to obtain such
consent.

                  (f) Lessor and Lessee hereby agree and consent that any
action or proceeding arising out of or brought to enforce the provisions of
this Lease may be brought in any appropriate court in Montgomery County,
Maryland or Baltimore City, Maryland, and, by the execution of this Lease,
Lessor and Lessee irrevocably consent to the jurisdiction of each such court.

                  (g) If for any reason Lessor or Lessee should become not
qualified to do business in the State, Lessor and Lessee hereby agree to
designate and appoint, without power of revocation, an agent for service of
process within the State, as the agent for Lessor or Lessee, as applicable,
upon whom may be served all process, pleadings, notice or other papers which
may be served upon Lessor or Lessee, as applicable, as a result of any of
Lessor's or Lessee's, as applicable, obligations under this Lease.

                  (h) Lessor and Lessee covenant that throughout the Term, if
a new agent for service of process within the State is designated pursuant to
the terms of subparagraph (g) above, Lessor or Lessee, as applicable, will
immediately file with the other party hereto the name and address of such new
agent and the date on which such appointment is to become effective.

                  (i) Lessor and Lessee hereby jointly waive trial by jury in
any action or proceeding to which Lessor and Lessee may be parties, arising
out of or in any way pertaining to this Lease. This waiver is knowingly,
willingly and voluntarily made by Lessor and Lessee, each of which hereby
represents that no representations of fact or opinion have been made by any
individual to induce this waiver of trial by jury or to in any way modify or
nullify its effect. Each of Lessor and Lessee further represents that it has
been represented in the signing of this Lease and in the making of this waiver
by independent legal counsel, selected of its own free will, and that it has
had the opportunity to discuss this waiver with counsel.

         38. Partial Release of Land.

         Notwithstanding anything to the contrary contained in this Lease and
in the other Operative Documents and subject to the satisfaction of the terms
and conditions set forth below, Lessor shall, within thirty (30) days after
receipt of a written request from Lessee notifying Lessor of Lessee's intent
to construct additional improvements on a portion of the Land for which the
Issuer and Credit Facility Providers have refused to provide financing,
execute an

                                      54

<PAGE>

amendment to this Lease and the other Operative Documents pursuant to which
the portion of the Land upon which such additional improvements shall be
constructed (the "Release Parcel") shall be released from this Lease and the
liens created hereby and in the other Operative Documents.

         Lessor's obligation to release the Release Parcel from this Lease and
the lien created hereby and in the other Operative Documents shall be subject
to the following terms and conditions:

                           (i)      No Default or Event of Default shall then
         be existing;

                           (ii)     Lessee shall be responsible, at Lessee's
         sole cost and expense, for preparing an ALTA Survey of the Release
         Parcel and for obtaining any and all required zoning, subdivision or
         other approvals from any applicable Governmental Authority having
         jurisdiction;

                           (iii)    Lessee shall be responsible for the costs
         of preparing and recording the required amendments to this Lease and
         the other Operative Documents to reflect the release of the Release
         Parcel from the liens created by this Lease and the other Operative
         Documents and for all other costs incurred by Lessor, the Agent, the
         Issuer and/or the Credit Facility Providers in connection with the
         release of the Release Parcel, including, without limitation, such
         parties' attorneys' fees;

                           (iv)     To the extent deemed necessary by Lessor,
         Agent or Issuer, Lessor and/or Issuer shall retain or reserve any
         easements over, upon, across and under the Release Parcel as may be
         necessary to support the continued use and operation of the Property;

                           (v)      Agent shall obtain, at the sole cost and
         expense of Lessee, an appraisal of the Fair Market Value of the
         Property, less the Release Parcel; and

                           (vi)     Lessee shall pay to Agent, for the benefit
         of the Credit Facility Providers, a release fee equal to the
         difference, if any, between the Fair Market Value of the Property as
         of the Commencement Date and the Fair Market Value of the Property,
         less the Release Parcel; provided, however, such release fee shall
         not exceed the Fair Market Value of the Release Parcel (the "Release
         Fee"), which amount shall be applied to the Lease Balance.

                  REMAINDER OF PAGE INTENTIONALLY LEFT BLANK

                                      55

<PAGE>

         IN WITNESS WHEREOF, Lessor and Lessee have caused this Lease to be
signed on their behalf, under seal, by their respective signatories thereunto
duly organized as of the date first above written.

                    LESSOR:

                    WELLS FARGO BANK NORTHWEST,
                    NATIONAL ASSOCIATION, not in its
                    individual capacity, but solely as Owner Trustee

                    By: /s/ VAL T. ORTON
                       ---------------------------------------------
                    Name:   Val T. Orton
                         -------------------------------------------
                    Title:  Vice President
                          ------------------------------------------

                            56

<PAGE>

                    LESSEE:

                    HUMAN GENOME SCIENCES, INC.

                    By:    /s/ STEVEN C. MAYER
                       ---------------------------------------------
                    Name:  Steven C. Mayer
                    Title: Senior Vice President and Chief Financial
                           Officer

<PAGE>

                                                                      EXHIBIT A

                             DESCRIPTION OF LAND

                                [TO BE ADDED]

                                     A-1

<PAGE>

                                                                      EXHIBIT B

                           [INTENTIONALLY OMITTED]

                                     B-1
<PAGE>

                                                                      EXHIBIT C

                                  BASIC RENT

         Subject to adjustment as provided in Paragraph 6(b) of this Lease,
Basic Rent, on each Payment Date, shall be an amount equal to the sum of (i)
the amount of interest payable on the aggregate sum of the outstanding
principal amount of the Bonds as of such Payment Date, (ii) the yield payable
on the aggregate sum of the outstanding principal amount of the Certificates
as of such Payment Date, and (iii) any other amounts and costs payable or
reimbursable pursuant to the Operative Documents as of such Payment Date,
including, without limitation, any amounts to be paid or reimbursable by the
Issuer, and the Lessor under the MEDCO Note, the Letter of Credit Documents
and the Head Lease.

                                     C-1

<PAGE>

                                                                      EXHIBIT D

                        NOTICE AND PAYMENT INFORMATION

If to Lessor:

         Notices:             Wells Fargo Bank Northwest, National Association
                              79 South Main Street, 3rd Floor
                              Salt Lake City, Utah  84111
                              Attention:   Val T. Orton
                                           Vice President

         Payments:            c/o [Allfirst Bank]
                              [ADD WIRING INSTRUCTIONS]

If to Lessee:

         Notices:             Human Genome Sciences, Inc.
                              9410 Key West Avenue
                              Rockville, Maryland  20850
                              Attention:   Steven C. Mayer
                                           Senior Vice President and
                                            Chief Financial Officer

                              with a copy to:

                              James H. Davis
                              Senior Vice President and General Counsel
                                   and Secretary
                              Human Genome Science, Inc.
                              9410 Key West Avenue
                              Rockville, Maryland  20850

If to Agent:

         Notices              Allfirst Bank
                              6303 Ivy Lane, Suite 200
                              Greenbelt, Maryland  20770
                              Attention:   Joseph C. LeMense
                                           Senior Vice President

                                     D-1

<PAGE>

                              Allfirst Bank
                              International Operations
                              25 South Charles Street
                              15th Floor
                              Baltimore, Maryland  21201
                              Attention:   Letter of Credit Department

                              with a copy to:

                              Nancy R. Little, Esq.
                              McGuireWoods LLP
                              One James Center
                              910 East Cary Street
                              Richmond, Virginia  23219

                                     D-2

<PAGE>

                                                                      EXHIBIT E

                      SECURITY AGREEMENT AND ASSIGNMENT

                               [TO BE ATTACHED]

                                     E-1

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