<PAGE>   1
                                                                     EXHIBIT 4.3


================================================================================



                          INCYTE PHARMACEUTICALS, INC.






                       5.5% Convertible Subordinated Notes
                                    Due 2007



                            ------------------------


                                    INDENTURE


                          Dated as of February 4, 2000


                            ------------------------




            STATE STREET BANK AND TRUST COMPANY OF CALIFORNIA, N.A.,
                                   AS TRUSTEE




================================================================================

<PAGE>   2

                               TABLE OF CONTENTS(1)



<TABLE>
<CAPTION>
                                                                                                                          Page
                                                                                                                          ----
<S>           <C>                                                                                                         <C>
ARTICLE 1. DEFINITIONS AND INCORPORATION BY REFERENCE.......................................................................1

               Section 1.1 Definitions......................................................................................1
               Section 1.2 Other Definitions................................................................................6
               Section 1.3 Incorporation by Reference of Trust Indenture Act................................................7
               Section 1.4 Rules of Construction............................................................................7

ARTICLE 2. THE SECURITIES...................................................................................................8

               Section 2.1 Designation, Form and Dating.....................................................................8
               Section 2.2 Execution and Authentication....................................................................10
               Section 2.3 Registrar, Paying Agent and Conversion Agent....................................................11
               Section 2.4 Paying Agent to Hold Money in Trust.............................................................12
               Section 2.5 Securityholder Lists............................................................................13
               Section 2.6 Transfer and Exchange...........................................................................13
               Section 2.7 Replacement Securities..........................................................................25
               Section 2.8 Outstanding Securities..........................................................................25
               Section 2.9 Treasury Securities.............................................................................26
               Section 2.10 Temporary Securities...........................................................................26
               Section 2.11 Cancellation...................................................................................26
               Section 2.12 CUSIP Numbers..................................................................................27

ARTICLE 3. REDEMPTION AND REPURCHASE.......................................................................................27

               Section 3.1 Right of Provisional Redemption.................................................................27
               Section 3.2 Right of Optional Redemption....................................................................27
               Section 3.3 Election to Redeem; Notice to Trustee...........................................................27
               Section 3.4 Selection of Securities To Be Redeemed..........................................................28
               Section 3.5 Notice of Redemption............................................................................28
               Section 3.6 Deposit of Redemption Price.....................................................................29
               Section 3.7 Securities Payable on Redemption Date...........................................................29
               Section 3.8 Securities Redeemed in Part.....................................................................30
               Section 3.9 Conversion Arrangement on Call for Redemption...................................................30
               Section 3.10 Repurchase of Securities at Option of the Holder upon Change in Control........................31
               Section 3.11 Conditions and Procedures Relating to the Company's Election to
                            Pay the Repurchase Price in Common Stock.......................................................33
               Section 3.12 Notice; Method of Exercising Repurchase Right..................................................34
               Section 3.13 Effect of Repurchase Notice....................................................................36
               Section 3.14 Deposit of Repurchase Price....................................................................37
               Section 3.15 Securities Repurchased in Part.................................................................37
</TABLE>



---------------------

(1)     This Table of Contents shall not, for any purpose, be deemed to be part
        of this Indenture.



                                       i

<PAGE>   3


<TABLE>
<S>            <C>                                                                                                        <C>
               Section 3.16 Compliance with Securities Laws upon Repurchase of Securities..................................37
               Section 3.17 Repayment to the Company.......................................................................38

ARTICLE 4. CONVERSION......................................................................................................38

               Section 4.1 Conversion Privilege............................................................................38
               Section 4.2 Conversion Procedure............................................................................39
               Section 4.3 Adjustments Below Par Value.....................................................................40
               Section 4.4 Taxes on Conversion.............................................................................40
               Section 4.5 Company to Provide Stock........................................................................40
               Section 4.6 Adjustment of Conversion Price..................................................................41
               Section 4.7 No Adjustment...................................................................................44
               Section 4.8 Equivalent Adjustments..........................................................................45
               Section 4.9 Adjustment for Tax Purposes.....................................................................45
               Section 4.10 Notice of Adjustment...........................................................................45
               Section 4.11 Notice of Certain Transactions.................................................................45
               Section 4.12 Effect of Reclassification, Consolidation, Merger or Sale on Conversion Privilege..............46
               Section 4.13 Trustee's Disclaimer...........................................................................47
               Section 4.14 Voluntary Reduction............................................................................47

ARTICLE 5. SUBORDINATION...................................................................................................48

               Section 5.1 Securities Subordinated to Senior Indebtedness..................................................48
               Section 5.2 Securities Subordinated to Prior Payment of All Senior Indebtedness on Dissolution,
                           Liquidation, Reorganization, Etc., of the Company...............................................48
               Section 5.3 Securityholders To Be Subrogated to Right of Holders of Senior Indebtedness.....................49
               Section 5.4 Obligations of the Company Unconditional........................................................50
               Section 5.5 Company Not To Make Payment with Respect to Securities in Certain Circumstances.................50
               Section 5.6 Notice to Trustee...............................................................................51
               Section 5.7 Application by Trustee of Monies Deposited with It..............................................52
               Section 5.8 Subordination Rights Not Impaired by Acts or Omissions of
                           Company or Holders of Senior Indebtedness.......................................................52
               Section 5.9 Trustee To Effectuate Subordination.............................................................52
               Section 5.10 Right of Trustee To Hold Senior Indebtedness...................................................53
               Section 5.11 Article 5 Not To Prevent Events of Default.....................................................53
               Section 5.12 No Fiduciary Duty Created to Holders of Senior Indebtedness....................................53
               Section 5.13 Article Applicable to Paying Agents............................................................53
               Section 5.14 Certain Conversion Deemed Payment..............................................................53

ARTICLE 6. COVENANTS.......................................................................................................54

               Section 6.1 Payment of Securities...........................................................................54
               Section 6.2 SEC Reports; 144A Information...................................................................54
               Section 6.3 Liquidation.....................................................................................55
</TABLE>


                                       ii


<PAGE>   4


<TABLE>
<S>           <C>                                                                                                         <C>
               Section 6.4 Compliance Certificates.........................................................................55
               Section 6.5 Notice of Defaults..............................................................................56
               Section 6.6 Payment of Taxes and Other Claims...............................................................56
               Section 6.7 Corporate Existence.............................................................................56
               Section 6.8 Maintenance of Properties.......................................................................56
               Section 6.9 Further Instruments and Acts....................................................................56
               Section 6.10 Maintenance of Office or Agency................................................................57
               Section 6.11 Resale of Certain Securities; Reporting Issuer.................................................57
               Section 6.12 Registration Rights............................................................................57
               Section 6.13 Additional Interest............................................................................58
               Section 6.14 Stay, Extension and Usury Laws.................................................................58

ARTICLE 7. SUCCESSOR CORPORATION...........................................................................................59

               Section 7.1 When Company May Merge, Etc.....................................................................59
               Section 7.2 Successor Corporation Substituted...............................................................59

ARTICLE 8. DEFAULT AND REMEDIES............................................................................................60

               Section 8.1 Events of Default...............................................................................60
               Section 8.2 Acceleration....................................................................................61
               Section 8.3 Other Remedies..................................................................................62
               Section 8.4 Waiver of Defaults and Events of Default........................................................62
               Section 8.5 Control by Majority.............................................................................62
               Section 8.6 Limitation on Suits.............................................................................62
               Section 8.7 Rights of Holders to Receive Payment............................................................63
               Section 8.8 Collection Suit by Trustee......................................................................63
               Section 8.9 Trustee May File Proofs of Claim................................................................63
               Section 8.10 Priorities.....................................................................................64
               Section 8.11 Undertaking for Costs..........................................................................64
               Section 8.12 Restoration of Rights and Remedies.............................................................64
               Section 8.13 Rights and Remedies Cumulative.................................................................65
               Section 8.14 Delay or Omission Not Waiver...................................................................65

ARTICLE 9. TRUSTEE.........................................................................................................65
               Section 9.1 Duties of Trustee...............................................................................65
               Section 9.2 Rights of Trustee...............................................................................66
               Section 9.3 Individual Rights of Trustee....................................................................67
               Section 9.4 Trustee's Disclaimer............................................................................67
               Section 9.5 Notice of Default or Events of Default..........................................................67
               Section 9.6 Reports by Trustee to Holders...................................................................67
               Section 9.7 Compensation and Indemnity......................................................................67
               Section 9.8 Replacement of Trustee..........................................................................68
               Section 9.9 Successor Trustee by Merger, Etc................................................................69
               Section 9.10 Eligibility; Disqualification..................................................................69
               Section 9.11 Preferential Collection of Claims Against Company..............................................69
</TABLE>


                                      iii



<PAGE>   5


<TABLE>
<S>           <C>                                                                                                         <C>
ARTICLE 10. SATISFACTION AND DISCHARGE OF INDENTURE........................................................................69

               Section 10.1 Termination of Company's Obligations...........................................................69
               Section 10.2 Application of Trust Money.....................................................................70
               Section 10.3 Repayment to Company...........................................................................70
               Section 10.4 Reinstatement..................................................................................71

ARTICLE 11. AMENDMENTS, SUPPLEMENTS AND WAIVERS............................................................................71

               Section 11.1 Without Consent of Holders.....................................................................71
               Section 11.2 With Consent of Holders........................................................................71
               Section 11.3 Compliance with Trust Indenture Act............................................................73
               Section 11.4 Revocation and Effect of Consents..............................................................73
               Section 11.5 Notation on or Exchange of Securities..........................................................73
               Section 11.6 Trustee To Sign Amendments, Etc................................................................73

ARTICLE 12. MISCELLANEOUS..................................................................................................73

               Section 12.1 Trust Indenture Act Controls...................................................................73
               Section 12.2 Notices........................................................................................74
               Section 12.3 Communications by Holders with Other Holders...................................................74
               Section 12.4 Certificate and Opinion as to Conditions Precedent.............................................74
               Section 12.5 Record Date for Vote or Consent of Securityholders.............................................75
               Section 12.6 Rules by Trustee, Paying Agent, Registrar......................................................75
               Section 12.7 Legal Holidays.................................................................................75
               Section 12.8 Governing Law..................................................................................76
               Section 12.9 No Adverse Interpretation of Other Agreements..................................................76
               Section 12.10 No Recourse Against Others....................................................................76
               Section 12.11 Successors....................................................................................76
               Section 12.12 Multiple Counterparts.........................................................................76
               Section 12.13 Separability..................................................................................76
               Section 12.14 Table of Contents, Headings, Etc..............................................................76

               Exhibit A..................................................................................................A-1
               Exhibit B-1...............................................................................................B1-1
               Exhibit B-2...............................................................................................B2-1
               Exhibit B-3...............................................................................................B3-1
               Exhibit B-4...............................................................................................B4-1
               Exhibit B-5...............................................................................................B5-1
               Exhibit B-6...............................................................................................B6-1
</TABLE>




                                       iv

<PAGE>   6

        INDENTURE dated as of February 4, 2000 between Incyte Pharmaceuticals,
Inc., a Delaware corporation (the "Company"), and State Street Bank and Trust
Company of California, N.A., a national banking association, as Trustee (the
"Trustee").

        Both parties agree as follows for the benefit of the other and for the
equal and ratable benefit of the registered holders of the Company's 5.5%
Convertible Subordinated Notes Due 2007.

                                   ARTICLE 1.

                   DEFINITIONS AND INCORPORATION BY REFERENCE

SECTION 1.1 DEFINITIONS. The terms defined in this Section 1.1 (except as herein
otherwise expressly provided or unless the context otherwise requires) for all
purposes of this Indenture and of any indenture supplemental hereto shall have
the respective meanings specified in this Section 1.1.

        "Affiliate" of any specified person means any other person directly or
indirectly controlling or controlled by or under direct or indirect common
control with such specified person. For the purposes of this definition,
"control" when used with respect to any person means the power to direct the
management and policies of such person, directly or indirectly, whether through
the ownership of voting securities, by contract or otherwise; and the terms
"controlling" and "controlled" have meanings correlative to the foregoing.

        "Agent" means any Registrar, Paying Agent or Conversion Agent.

        "Applicable Procedures" means any procedures required to be followed by
the Depositary, Euroclear or Clearstream Banking including, but not limited to,
the "Operating Procedures of the Euroclear System" and "Terms and Conditions
Governing Use of Euroclear" and the "Management Regulations" and "Instructions
to Participants" of Clearstream Banking.

        "Associate" shall have the meaning ascribed to such term in Rule 12b-2
of the General Rules and Regulations under the Exchange Act, as such Rule is in
effect on the date of this Indenture.

        "Board of Directors" means the Board of Directors of the Company or any
authorized committee of the Board of Directors, except that for the purposes of
Section 3.8 "Board of Directors" shall mean the entire Board of Directors of the
Company.

        "Business Day" means a day that is not a Legal Holiday.

        "Cash" or "cash" means such coin or currency of the United States as at
any time of payment is legal tender for the payment of public and private debts.

        "Certificated Note" means a Security issued to a purchaser in definitive
form in the form of Note attached hereto as Exhibit A that contains the
Certificated Note Restricted Securities Legend, if applicable, but that does not
contain the Global Note Legend, the Global Note Insert or the Global Note
Transfer Schedule.



                                       1
<PAGE>   7

        "Common Stock" means any stock of any class of the Company which has no
preference in respect of dividends or of amounts payable in the event of any
voluntary or involuntary liquidation, dissolution or winding up of the Company
and which is not subject to redemption by the Company. Subject to the provisions
of Section 4.12, however, shares issuable on conversion of Securities shall
include only shares of Common Stock, $0.001 par value per share (which is the
class designated as Common Stock of the Company at the date of this Indenture),
or shares of any class or classes resulting from any reclassification or
reclassifications thereof and which have no preference in respect of dividends
or of amounts payable in the event of any voluntary or involuntary liquidation,
dissolution or winding up of the Company and which are not subject to redemption
by the Company; provided that if at any time there shall be more than one such
resulting class, the shares of each such class then so issuable shall be
substantially in the proportion to which the total number of shares of such
class resulting from all such reclassifications bears to the total number of
shares of all such classes resulting from all such reclassifications.

        "Company" means the party named as such in this Indenture until a
successor replaces it pursuant to this Indenture and thereafter means the
successor.

        "Consolidated Net Worth" means, with respect to any Person, the
consolidated stockholders' equity (excluding any capital stock that by its terms
is, or upon the happening of an event or passage of time would be, required to
be redeemed prior to the maturity of the Securities or is redeemable at the
option of the holder thereof at any time prior to such maturity or is
convertible or exchangeable for debt securities at any time prior to such
maturity at the option of the holder thereof) of such Person and its
consolidated subsidiaries, as determined in accordance with generally accepted
accounting principles.

        "Corporate Trust Office" of the Trustee means the office of the Trustee
at which this Indenture is administered, which office initially is located at
633 West 5th Street, 12th Floor, Los Angeles, CA 90071, attention: Corporate
Trust Department, (Incyte Pharmaceuticals, Inc. 5.5% Convertible Subordinated
Notes Due 2007).

        "Default" or "default" means any event which is, or after notice or
passage of time, or both, would be, an Event of Default.

        "Depositary" means, with respect to the Securities issuable or issued in
whole or in part in global form, the person specified in Section 2.6(g) as the
Depositary with respect to the Securities, until a successor shall have been
appointed and become such pursuant to the applicable provisions of this
Indenture, and thereafter, "Depositary" shall mean or include such successor.

        "Global Notes" means, individually and collectively, the Regulation S
Global Note and the Rule 144A Global Note.

        "Holder" or "Securityholder" means the person in which name a Security
is registered on the Registrar's books.

        "Indenture" means this Indenture as amended or supplemented from time to
time.



                                       2
<PAGE>   8

        "Initial Purchasers" means Deutsche Bank Securities Inc. and Warburg
Dillon Read LLC, as Initial Purchasers under the Purchase Agreement.

        "Institutional Accredited Investor" means an institutional "accredited
investor" as defined in Rule 501(a)(1), (2), (3) or (7) under the Securities
Act.

        "Instrument" means any agreement, indenture, instrument or other
document under which any obligation is evidenced, assumed, guaranteed or
secured.

        "Investment" means, with respect to any Person, directly or indirectly,
any advance, loan or other extension of credit or capital contribution to, or
any purchase, acquisition or ownership by such Person of any capital stock,
bonds, notes, debentures or other securities issued or owned by any other
Person.

        "Market Capitalization" means an amount determined by multiplying the
number of shares of Common Stock outstanding on the applicable date by the
current market price of the Common Stock (determined as provided in Section
4.6(e)) as of such date.

        "Officer" means the Chairman of the Board, the President, any Vice
President, the Chief Financial Officer, the Treasurer or the Secretary of the
Company.

        "Officers' Certificate" means a certificate signed by two Officers of
the Company; provided, however, that for purposes of Section 6.4 "Officers'
Certificate" means a certificate signed by the principal executive officer,
principal financial officer or principal accounting officer of the Company.

        "Opinion of Counsel" means a written opinion from legal counsel to the
Trustee. The counsel may be an employee of or counsel to the Company or the
Trustee.

        "Payment Default" means any default in the payment of principal of (or
premium, if any) or interest on Senior Indebtedness.

        "Payment in full" or "paid in full" means payment in full in cash.

        "Person" or "person" means any individual, corporation, partnership,
joint venture, association, joint-stock company, trust, unincorporated
organization or government or other agency or political subdivision thereof.

        "PORTAL Market" means the Private Offerings, Resales and Trading through
Automated Linkages Market operated by the National Association of Securities
Dealers, Inc. or any successor thereto.

        "Principal" or "principal" of a debt security, including the Securities,
means the principal of the security plus, when appropriate, the premium, if any
(including the Make-Whole Payment, if any), on the security.

        "Purchase Agreement" means the Purchase Agreement dated February 1, 2000
among the Company, Deutsche Bank Securities Inc. and Warburg Dillon Read LLC.



                                       3
<PAGE>   9

        "Purchase Option" means the option to purchase up to $50,000,000 in
aggregate principal amount of Securities granted by the Company to the Initial
Purchasers pursuant to the Purchase Agreement.

        "QIB" means a "Qualified Institutional Buyer" as that term is defined in
Rule 144A.

        "Redemption Date" or "redemption date," when used with respect to any
Security to be redeemed, means the date fixed for such redemption pursuant to
this Indenture, as set forth in the form of Security annexed as Exhibit A
hereto.

        "Redemption Price" or "redemption price," when used with respect to any
Security to be redeemed, means the price fixed for such redemption pursuant to
this Indenture, as set forth in the form of Security annexed as Exhibit A
hereto.

        "Registration Rights Agreement" means the Registration Rights Agreement
dated as of February 4, 2000 between the Company and the Initial Purchasers and
certain permitted assigns.

        "Regulation S" means Regulation S promulgated under the Securities Act.

        "Regulation S Global Note" means a permanent global note in the form of
the Note attached hereto as Exhibit A that contains the Global Note Legend, the
Global Note Insert and the Global Note Transfer Schedule as each is set forth in
Exhibit A hereto, and that is deposited with and is registered in the name of
the Depositary, representing a series of Notes sold in reliance on Regulation S.

        "Reorganization Securities" means securities of the Company or any other
corporation provided for by a plan of reorganization or readjustment of the
Company (a) which are equity securities that do not provide for any mandatory
payments to holders thereof, including by way of dividends or mandatory
redemption; or (b) the payment of which is subordinated, at least to the extent
provided in Article 5 with respect to the Securities, to the payment of all
Senior Indebtedness which may at the time be outstanding.

        "Representative" means the indenture trustee or other trustee, agent or
representative for any class of Senior Indebtedness.

        "Restricted Security" means each Security, other than a Regulation S
Global Note, until the earliest to occur of (a) the date on which such Note has
been effectively registered under the Securities Act and disposed of in
accordance with a shelf registration statement pursuant to the Registration
Rights Agreement and (b) the date on which such Note is distributed to the
public pursuant to Rule 144 under the Securities Act. Each Restricted Security
shall bear the appropriate legend set forth in Section 2.6(g).

        "Rule 144" means Rule 144 as promulgated under the Securities Act.

        "Rule 144A" means Rule 144A as promulgated under the Securities Act.

        "Rule 144A Global Note" means a permanent global note in the form of the
Note attached hereto as Exhibit A that contains the Global Note Insert, the
Global Note Legend, the



                                       4
<PAGE>   10

Global Note Transfer Schedule and the Global Note Restricted Securities Legend
(if applicable), as each such legend or schedule is set forth in Exhibit A
hereto, and that is deposited with and registered in the name of the Depositary,
representing a series of Notes sold in reliance on Rule 144A.

        "SEC" or "Commission" means the Securities and Exchange Commission.

        "Securities" means the 5.5% Convertible Subordinated Notes Due 2007 or
any of them (each a "Security"), as amended or supplemented from time to time,
that are issued under this Indenture.

        "Securities Act" means the Securities Act of 1933, as amended, and the
rules and regulations promulgated thereunder.

        "Senior Agent" means, on any date, the Representative of the class of
Senior Indebtedness having the highest principal amount (including all revolving
credit, letter of credit and other working capital commitments) then
outstanding.

        "Senior Indebtedness" means the following, whether outstanding upon
issuance of the Notes or thereafter incurred or created: (a) the principal of
and premium, if any, and interest on, and fees, costs, enforcement expenses,
collateral protection expenses and other reimbursements or indemnity obligations
in respect of all indebtedness or obligations of the Company to any Person,
including but not limited to banks and other lending institutions, for money
borrowed that is evidenced by a note, bond, debenture, loan agreement, or
similar instrument or agreement (including purchase money obligations with
original maturities in excess of one year and noncontingent reimbursement
obligations in respect of amounts paid under letters of credit); (b) commitment
or standby fees due and payable to lending institutions with respect to credit
facilities available to the Company; (c) all noncontingent obligations of the
Company (i) for the reimbursement of any obligor on any letter of credit,
banker's acceptance, or similar credit transaction, (ii) under interest rate
swaps, caps, collars, options, and similar arrangements, and (iii) under any
foreign exchange contract, currency swap agreement, futures contract, currency
option contract, or other foreign currency hedge; (d) all obligations of the
Company for the payment of money relating to capitalized lease obligations; (e)
any liabilities of others described in the preceding clauses that the Company
has guaranteed or which are otherwise its legal liability; and (f) renewals,
extensions, refundings, refinancings, restructurings, amendments, and
modifications of any such indebtedness or guarantee; other than any indebtedness
or other obligation of the Company that by its terms or the terms of the
instrument creating or evidencing it is stated to be not superior in right of
payment to the Notes.

        "Subsidiary" means any corporation, association or other business entity
of which at least a majority of the total capital stock entitled (without regard
to the occurrence of any contingency) to vote in the election of directors,
managers or trustees thereof is at the time owned or controlled, directly or
indirectly, by the Company or one or more of other Subsidiaries or a combination
thereof.

        "TIA" means the Trust Indenture Act of 1939, as amended by the Trust
Indenture Reform Act of 1990 and as in effect on the date of this Indenture,
except as provided in Section 11.3



                                       5
<PAGE>   11

hereof, and except to the extent any amendment to the Trust Indenture Act
expressly provides for application of the Trust Indenture Act as in effect on
another date.

        "Transfer Restricted Security" means securities that bear or are
required to bear the Legend set forth in Section 2.6(g) hereof.

        "Trustee" means State Street Bank and Trust Company of California, N.A.
until a successor replaces it in accordance with the provisions of this
Indenture and thereafter means the successor.

        "Trust Officer" means any officer in the Corporate Trust Office of the
Trustee or any other officer customarily performing functions similar to those
performed by any of the above-designated officers who shall, in any case, be
responsible for the administration of this Indenture or have familiarity with
it, and also means, with respect to a particular corporate matter, any other
officer of the Trustee to whom corporate trust matters are referred because of
his knowledge of and familiarity with the particular subject.

        "U.S. Person" has the meaning specified in Regulation S.

SECTION 1.2 OTHER DEFINITIONS.


<TABLE>
<CAPTION>
                                                                                                    Defined
Term                                                                                               in Section
----                                                                                               ----------
<S>                                                                                                  <C>
"Additional Interest"..........................................................................      6.12
"Affiliate Legend".............................................................................      2.6(g)(iii)
"Agent Members"................................................................................      2.1(b)
"Bankruptcy Law"...............................................................................      8.1
"Beneficial Owner".............................................................................      3.10
"Certificated Note Restricted Securities Legend"...............................................      2.6(g)
"Change in Control"............................................................................      3.10
"Clearstream"..................................................................................      2.1(a)
"Closing Price"................................................................................      4.6
"Company Benefit Plan..........................................................................      4.6(c)
"Company Notice"...............................................................................      3.12
"Company Order"................................................................................      2.2
"Conversion Agent".............................................................................      2.3
"Conversion Price".............................................................................      4.6
"Conversion Shares"............................................................................      4.6(c)
"Custodian"....................................................................................      8.1
"Distribution Date"............................................................................      4.6(c)
"Euroclear"....................................................................................      2.1(a)
"Event of Default".............................................................................      8.1
"Exchange Act".................................................................................      3.10
"Global Note Restricted Securities Legend......................................................      2.6(g)
"Legal Holiday"................................................................................      12.7
"Make-Whole Payment"...........................................................................      3.1
</TABLE>



                                       6
<PAGE>   12

<TABLE>
<CAPTION>
                                                                                                    Defined
Term                                                                                               in Section
----                                                                                               ----------
<S>                                                                                                  <C>
"Optional Redemption"..........................................................................      3.2
"Paying Agent".................................................................................      2.3
"Payment Blockage Period"......................................................................      5.5
"Payment of the Securities"....................................................................      5.5
"Provisional Redemption".......................................................................      3.1
"Provisional Redemption Date"..................................................................      3.1
"Publicly Traded Securities"...................................................................      3.10
"Redemption Notice Date".......................................................................      3.1
"Registrar"....................................................................................      2.3
"Registration Default".........................................................................      6.12
"Repurchase Date"..............................................................................      3.10
"Repurchase Price".............................................................................      3.10
"Repurchase Notice"............................................................................      3.12(b)
"Restricted Stock Legend"......................................................................      2.6(g)(ii)
"Rights".......................................................................................      4.6(c)
"Securities Act"...............................................................................      2.1
"Shelf Registration Statement".................................................................      6.12(a)
"Trading Days".................................................................................      4.6(e)
"Trigger Event"................................................................................      4.6(f)
"U.S. Government Obligations"..................................................................      10.1
"Voting Shares"................................................................................      3.10
</TABLE>


SECTION 1.3 INCORPORATION BY REFERENCE OF TRUST INDENTURE ACT.

        This Indenture is hereby made subject to, and shall be governed by, the
provisions of the TIA required to be part of and to govern indentures qualified
under the TIA. The following TIA terms used in this Indenture have the following
meanings:

        "Commission" means the SEC.
        "indenture securities" means the Securities.
        "indenture security holder" means a Securityholder.
        "indenture to be qualified" means this Indenture.
        "indenture trustee" or "institutional trustee" means the Trustee.
        "obligor" on the indenture securities means the Company or any other
        obligor on the Securities.

        All other terms used in this Indenture that are defined in the TIA,
defined by a TIA reference to another statute or defined by SEC rule and not
otherwise defined herein have the meanings assigned to them therein.

SECTION 1.4 RULES OF CONSTRUCTION.

        Unless the context otherwise requires:



                                       7
<PAGE>   13

        (1) a term has the meaning assigned to it;

        (2)an accounting term not otherwise defined has the meaning assigned to
it in accordance with generally accepted accounting principles in effect on the
date hereof, and any other reference in this Indenture to "generally accepted
accounting principles" refers to generally accepted accounting principles in
effect on the date hereof;

        (3) "or" is not exclusive;

        (4) words in the singular include the plural, and words in the plural
include the singular;

        (5) provisions apply to successive events and transactions; and

        (6) "herein," "hereof" and other words of similar import refer to this
Indenture as a whole and not to any particular Article, Section or other
subdivision.

                                   ARTICLE 2.

                                 THE SECURITIES

SECTION 2.1 DESIGNATION, FORM AND DATING.

        The Securities shall be designated as the "5.5% Convertible Subordinated
Notes Due 2007." Other than as provided in Section 2.1(a) hereof, the Securities
and the Trustee's certificate of authentication to be borne by the Securities
shall be substantially in the form of Exhibit A attached hereto, which is
incorporated in and made part of this Indenture. The Company and the Trustee, by
their execution and delivery of this Indenture, expressly agree to the terms and
provisions of the Securities and to be bound thereby. In addition to such
legends as may be required pursuant to Section 2.6(g) hereof, any of the
Securities may have imprinted thereon such legends or endorsements as the
officers executing the same may approve (execution thereof to be conclusive
evidence of such approval) and as are not inconsistent with the provisions of
this Indenture, or as may be required to comply with any law or with any rule or
regulation made pursuant thereto or with any rule or regulation of any stock
exchange on which the Securities may be listed or any trading system in which
the Securities may be admitted, or to conform to usage. Each Security shall be
dated the date of its authentication.

        (a) Global Notes. Securities offered and sold to QIBs in reliance on
Rule 144A shall be issued initially in the form of Rule 144A Global Notes in the
form of the Note attached hereto as Exhibit A, with the Global Securities
Legend, the Global Note Insert and the Global Note Transfer Schedule as each is
set forth in Exhibit A hereto. Such Rule 144A Global Notes shall be deposited on
behalf of the purchasers of the Securities represented thereby with the
Depositary at its New York office, and registered in the name of the Depositary
or a nominee of the Depositary, duly executed by the Company and authenticated
by the Trustee as hereinafter provided. The aggregate principal amount of the
Rule 144A Global Notes may from time to time be increased or decreased by
adjustments made on the records of the Trustee and the Depositary or its nominee
as hereinafter provided. Payment of principal of and interest and premium, if
any



                                       8
<PAGE>   14

(including the Make-Whole Payment, if any), on any Security in global form shall
be made to the holder of such Security.

        Securities offered and sold in reliance on Regulation S shall be issued
initially in the form of Regulation S Global Notes in the form of the Note
attached hereto as Exhibit A with the Global Note Legend, the Global Note Insert
and the Global Note Transfer Schedule as each is set forth in Exhibit A hereto.
Such Regulation S Global Notes shall be deposited on behalf of the purchaser of
the Securities represented thereby with the Depositary or a custodian of the
Depositary and registered in the name of the Depositary or the nominee of the
Depositary for the accounts of designated agents holding on behalf of the
Euroclear System ("Euroclear") or Clearstream Banking ("Clearstream"), duly
executed by the Company and authenticated by the Trustee as hereinafter
provided. The aggregate principal amount of the Regulation S Global Notes may
from time to time be increased or decreased by adjustments made on the records
of the Trustee and the Depositary or its nominee, as the case may be, in
connection with transfers of interest as hereinafter provided.

        Each Global Note shall represent such of the outstanding Securities as
shall be specified therein and each shall provide that it shall represent the
aggregate amount of outstanding Securities from time to time endorsed thereon
and that the aggregate amount of outstanding Securities represented thereby may
from time to time be reduced or increased, as appropriate, to reflect exchanges
and redemptions. Any endorsement of a Global Note to reflect the amount of any
increase or decrease in the amount of outstanding Securities represented thereby
shall be made by the Trustee or the Securities Custodian, at the direction of
the Trustee, in accordance with instructions given by the Holder thereof.

        The provisions of the "Operating Procedures of the Euroclear System" and
"Terms and Conditions Governing Use of Euroclear" and the "Management
Regulations" and "Instructions to Participants" of Clearstream shall be
applicable to interests in the Regulation S Global Notes that are held by the
Agent Members through Euroclear or Clearstream.

        Except as set forth in Section 2.6 hereof, the Global Notes may be
transferred, in whole and not in part, only to another nominee of the Depositary
or to a successor of the Depositary or its nominee. The Trustee and the Company
shall treat the Holder of any Global Note as the owner of such Security for the
purpose of receiving payment of the principal of, premium, if any (including the
Make-Whole Payment, if any), and interest on such Global Note and for all other
purposes whatsoever.

        In addition to such legends as may be required pursuant to Section
2.6(g) hereof, any Security in global form may be endorsed with or have
incorporated in the text thereof such legends or recitals or changes not
inconsistent with the provisions of this Indenture as may be required by the
Depositary or by the National Association of Securities Dealers, Inc. in order
for the Securities to be tradeable on the PORTAL Market or as may be required
for the Securities to be tradeable on any other market developed for trading of
securities pursuant to Rule 144A or required to comply with any applicable law
or any regulation thereunder or with the rules and regulations of any securities
exchange upon which the Securities may be listed or traded or to conform with
any usage with respect thereto, or to indicate any special limitations or
restrictions to which any particular Securities are subject.



                                       9
<PAGE>   15

        (b) Book-Entry Provisions. This Section 2.1(b) shall apply only to Rule
144A Global Notes and the Regulation S Global Notes deposited with or on behalf
of the Depositary.

        The Company shall execute and the Trustee shall, in accordance with this
Section 2.1(b), authenticate and deliver the Global Notes that (i) shall be
registered in the name of the Depositary or the nominee of the Depositary and
(ii) shall be delivered by the Trustee to the Depositary or pursuant to the
Depositary's instructions or held by the Trustee as custodian for the
Depositary.

        Members of, or participants in, the Depositary ("Agent Members") shall
have no rights either under this Indenture with respect to any Global Note held
on their behalf by the Depositary or by the Trustee as custodian for the
Depositary or under such Global Note, and the Depositary may be treated by the
Company, the Trustee and any agent of the Company or the Trustee as the absolute
owner of such Global Note for all purposes whatsoever. Notwithstanding the
foregoing, nothing herein shall prevent the Company, the Trustee or any agent of
the Company or the Trustee from giving effect to any written certification,
proxy or other authorization furnished by the Depositary or impair, as between
the Depositary and its Agent Members, the operation of customary practices of
such Depositary governing the exercise of the rights of an owner of a beneficial
interest in any Global Note.

        (c) Certificated Securities. Except as provided in Section 2.10, owners
of beneficial interest in Global Notes will not be entitled to receive physical
delivery of Certificated Notes. Purchasers of Securities who are not QIBs and
did not purchase Securities sold in reliance on Regulation S under the
Securities Act will receive Certificated Notes bearing the Certificated Note
Restricted Securities Legend as set forth in Section 2.6(g) hereof. Certificated
Notes will bear the Certificated Note Restricted Securities Legend set forth in
Section 2.6(g) hereof unless removed in accordance with Section 2.6(g) hereof
and may not be exchanged for a Global Note, or interest therein, at any time.

        Pursuant to Section 2.6(g) hereof, the Certificated Securities and
shares of Common Stock issuable upon conversion thereof shall be required, in
certain circumstances described in Section 2.6(g), to bear legends restricting
their transfer. By its acceptance of any Security or share of Common Stock
bearing the aforesaid legend, each Holder acknowledges the restrictions on
transfer set forth on such Security or share of Common Stock and agrees that it
will transfer such Security or share of Common Stock only as provided thereon.

SECTION 2.2 EXECUTION AND AUTHENTICATION.

        Two Officers of the Company shall sign the Certificated Securities for
the Company by manual or facsimile signature. If an Officer whose signature is
on a Security no longer holds that office at the time the Trustee authenticates
the Security, the Security shall be valid nevertheless. A Security shall not be
valid until an authorized signatory of the Trustee manually signs the
certificate of authentication on the Security. The signature shall be conclusive
evidence that the Security has been authenticated under this Indenture.

        The Trustee shall authenticate and make available for delivery
Securities for original issue in the aggregate principal amount of up to
$150,000,000, upon a written order or orders of



                                       10
<PAGE>   16

the Company signed by two Officers or by an Officer and an Assistant Treasurer
or Assistant Secretary of the Company (a "Company Order"). The Company Order
shall specify the amount of Securities to be authenticated and the date on which
the original issue of Securities is to be authenticated. Upon the exercise of
the Purchase Option by the Initial Purchasers, additional Securities in the
aggregate principal amount of up to $50,000,000 shall be executed by the Company
in the aforementioned manner and delivered to the Trustee for authentication,
and shall thereupon be authenticated and delivered by the Trustee upon Company
Order. The aggregate principal amount of Securities outstanding under this
Indenture at any time may not exceed $200,000,000, except as provided in Section
2.7.

        The Trustee shall act as the initial authenticating agent. Thereafter,
the Trustee may appoint an authenticating agent acceptable to the Company to
authenticate Securities. An authenticating agent may authenticate Securities
whenever the Trustee may do so. Each reference in this Indenture to
authentication by the Trustee includes authentication by such agent. An
authenticating agent has the same rights as an Agent to deal with the Company or
an Affiliate of the Company.

        The Securities shall be issuable only in registered form without coupons
only in denominations of $1,000 and any integral multiple thereof.

SECTION 2.3 REGISTRAR, PAYING AGENT AND CONVERSION AGENT.


        The Company shall maintain an office or agency where Securities may be
presented for registration of transfer or for exchange (the "Registrar"), an
office or agency where Securities may be presented for payment (the "Paying
Agent"), an office or agency where Securities may be presented for conversion
(the "Conversion Agent") and an office or agency where notices and demands to or
upon the Company in respect of the Securities and this Indenture may be served.
The Registrar shall keep a register of the Securities and of their transfer and
exchange. The Company may have one or more co-Registrars, one or more additional
Paying Agents and one or more additional Conversion Agents. The term "Registrar"
includes any co-Registrar, the term "Paying Agent" includes any additional
Paying Agent and the term "Conversion Agent" includes any additional Conversion
Agent.

        The Company shall enter into an appropriate agency agreement with any
Agent not a party to this Indenture. The agreement shall implement the
provisions of this Indenture that relate to such Agent. The Company shall notify
the Trustee of the name and address of any Agent not a party to this Indenture.
If the Company fails to maintain a Registrar, Paying Agent, Conversion Agent or
agent for service of notices and demands, or fails to give the foregoing notice,
the Trustee shall act as such. The Company or any Affiliate of the Company may
act as Paying Agent (except for the purposes of Section 6.3 and Article 10),
Registrar or Conversion Agent.

        The Company initially appoints the Trustee as Registrar, Paying Agent,
Conversion Agent and agent for service of notices and demands in connection with
the Securities.

SECTION 2.4 PAYING AGENT TO HOLD MONEY IN TRUST.

                                       11
<PAGE>   17
        If the Company shall at any time act as its own Paying Agent, it will,
on or before each due date of the principal of and premium, if any (including
the Make-Whole Payment, if any), or interest (together with any Additional
Interest in respect thereof) on any of the Securities, segregate and hold in
trust for the benefit of the Persons entitled thereto a sum sufficient to pay
the principal of, premium, if any (including the Make-Whole Payment, if any), or
interest on any of the Securities (together with any Additional Interest in
respect thereof) so becoming due until such sums shall be paid to such Persons
or otherwise disposed of as herein provided and will promptly notify the Trustee
of its action or failure so to act.

        Whenever the Company shall have one or more Paying Agents, it will,
prior to each due date of the principal of and premium, if any (including the
Make-Whole Payment, if any), or interest (together with any Additional Interest
in respect thereof) on any Securities, deposit with a Paying Agent a sum
sufficient to pay such amount, such sum to be held in trust for the benefit of
the Persons entitled to such principal, premium, if any, or interest, and
(unless such Paying Agent is the Trustee) the Company will promptly notify the
Trustee of its action or failure so to act.

        The Company will cause each Paying Agent other than the Trustee to
execute and deliver to the Trustee an instrument in which such Paying Agent
shall agree with the Trustee, subject to the provisions of this Section 2.4,
that such Paying Agent will, subject to Section 5.7:

        (1) hold all sums held by it for the payment of the principal of,
premium, if any (including the Make-Whole Payment, if any), or interest on
Securities in trust for the benefit of the Persons entitled thereto until such
sums shall be paid to such Persons or otherwise disposed of as herein provided;

        (2) give the Trustee notice of any default by the Company (or any other
obligor upon the Securities) in the making of any payment of principal, premium,
if any (including the Make-Whole Payment, if any), or interest; and

        (3) at any time during the continuance of any such default, upon the
written request of the Trustee, forthwith pay to the Trustee all sums so held in
trust by such Paying Agent.

        Any money deposited with the Trustee or any Paying Agent, or then held
by the Company in trust for the payment of the principal of, and premium, if any
(including the Make-Whole Payment, if any), or interest (together with any
Additional Interest in respect thereof) on any Security and remaining unclaimed
for two years after such principal and premium, if any (including the Make-Whole
Payment, if any), or interest has become due and payable shall be paid to the
Company on written request of the Company, or (if then held by the Company)
shall be discharged from such trust; and the Holder of such Security shall
thereafter, as an unsecured general creditor, look only to the Company for
payment thereof, and all liability of the Trustee or such Paying Agent with
respect to such trust money, and all liability of the Company as trustee
thereof, shall thereupon cease; provided, however, that the Trustee or such
Paying Agent, before being required to make any such repayment, may at the
expense of the Company cause to be published once, in a newspaper published in
the English language, customarily published on each Business Day and of general
circulation in the Borough of Manhattan, The City of New York, notice that such
money remains unclaimed and that, after a date specified therein, which shall
not


                                       12
<PAGE>   18


be less than 30 days from the date of such publication, any unclaimed balance of
such money then remaining will be repaid to the Company.

SECTION 2.5 SECURITYHOLDER LISTS.

        The Trustee shall preserve in as current a form as is reasonably
practicable the most recent list available to it of the names and addresses of
Securityholders. If the Trustee is not the Registrar, the Company shall furnish
to the Trustee on or before each semi-annual interest payment date and at such
other times as the Trustee may request in writing a list in such form and as of
such date as the Trustee may reasonably require of the names and addresses of
Securityholders.

SECTION 2.6 TRANSFER AND EXCHANGE.

        (a) Transfer and Exchange of Global Notes. The transfer and exchange of
Global Notes or beneficial interests therein shall be effected through the
Depositary, in accordance with this Indenture and the Applicable Procedures,
which shall include restrictions on transfer comparable to those set forth
herein to the extent required by the Securities Act. Beneficial interests in a
Global Note may be transferred to Persons who take delivery thereof in the form
of a beneficial interest in the same Global Note in accordance with the transfer
restrictions set forth in the legend in subsection (g) of this Section 2.6.
Transfers of beneficial interests in the Global Notes to Persons required to
take delivery thereof in the form of an interest in another Global Note shall be
permitted as follows:

           (i) Rule 144A Global Note to Regulation S Global Note. If, at any
time, an owner of a beneficial interest in a Rule 144A Global Note deposited
with the Depositary (or the Trustee as custodian for the Depositary) wishes to
transfer its interest in such Rule 144A Global Note to a Person who is required
or permitted to take delivery thereof in the form of an interest in a Regulation
S Global Note, such owner shall, subject to the Applicable Procedures, exchange
or cause the exchange of such interest for an equivalent beneficial interest in
a Regulation S Global Note as provided in this Section 2.6(a)(i). Upon receipt
by the Trustee of (1) instructions given in accordance with the Applicable
Procedures from an Agent Member directing the Trustee to credit or cause to be
credited a beneficial interest in the Regulation S Global Note in an amount
equal to the beneficial interest in the Rule 144A Global Note to be exchanged,
(2) a written order given in accordance with the Applicable Procedures
containing information regarding the participant account of the Depositary and
the Euroclear or Clearstream account to be credited with such increase, and (3)
a certificate in the form of Exhibit B-2 hereto given by the owner of such
beneficial interest stating that the transfer of such interest has been made in
compliance with the transfer restrictions applicable to the Global Notes and
pursuant to and in accordance with Rule 903 or Rule 904 of Regulation S, then
the Trustee, as Registrar, shall instruct the Depositary to reduce or cause to
be reduced the aggregate principal amount at maturity of the applicable Rule
144A Global Note and to increase or cause to be increased the aggregate
principal amount at maturity of the applicable Regulation S Global Note by the
principal amount at maturity of the beneficial interest in the Rule 144A Global
Note to be exchanged, to credit or cause to be credited to the account



                                       13
<PAGE>   19
of the Person specified in such instructions a beneficial interest in the
Regulation S Global Note equal to the reduction in the aggregate principal
amount at maturity of the Rule 144A Global Note, and to debit, or cause to be
debited, from the account of the Person making such exchange or transfer the
beneficial interest in the Rule 144A Global Note that is being exchanged or
transferred.

           (ii) Regulation S Global Note to Rule 144A Global Note. If, at any
time, an owner of a beneficial interest in a Regulation S Global Note deposited
with the Depositary or with the Trustee as custodian for the Depositary wishes
to transfer its interest in such Regulation S Global Note to a Person who is
required or permitted to take delivery thereof in the form of an interest in a
Rule 144A Global Note, such owner shall, subject to the Applicable Procedures,
exchange or cause the exchange of such interest for an equivalent beneficial
interest in a Rule 144A Global Note as provided in this Section 2.6(a)(ii). Upon
receipt by the Trustee of (1) instructions from Euroclear or Clearstream, if
applicable, and the Depositary, directing the Trustee, as Registrar, to credit
or cause to be credited a beneficial interest in the Rule 144A Global Note equal
to the beneficial interest in the Regulation S Global Note to be exchanged, such
instructions to contain information regarding the participant account with the
Depositary to be credited with such increase, (2) a written order given in
accordance with the Applicable Procedures containing information regarding the
participant account of the Depositary and (3) a certificate in the form of
Exhibit B-3 attached hereto given by the owner of such beneficial interest
stating (A) if the transfer is pursuant to Rule 144A, that the Person
transferring such interest in a Regulation S Global Note reasonably believes
that the Person acquiring such interest in a Rule 144A Global Note is a QIB and
is obtaining such beneficial interest in a transaction meeting the requirements
of Rule 144A and any applicable blue sky or securities laws of any state of the
United States, (B) that the transfer complies with the requirements of Rule 144
under the Securities Act and any applicable blue sky or securities laws of any
state of the United States or (C) if the transfer is pursuant to any other
exemption from the registration requirements of the Securities Act, that the
transfer of such interest has been made in compliance with the transfer
restrictions applicable to the Global Notes and pursuant to and in accordance
with the requirements of the exemption claimed, such statement to be supported
by an Opinion of Counsel from the transferee or the transferor in form
reasonably acceptable to the Company and to the Registrar, then the Trustee, as
Registrar, shall instruct the Depositary to reduce or cause to be reduced the
aggregate principal amount at maturity of such Regulation S Global Note and to
increase or cause to be increased the aggregate principal amount at maturity of
the applicable Rule 144A Global Note by the principal amount at maturity of the
beneficial interest in the Regulation S Global Note to be exchanged, and the
Trustee, as Registrar, shall instruct the Depositary, concurrently with such
reduction, to credit or cause to be credited to the account of the Person
specified in such instructions a beneficial interest in the applicable Rule 144A
Global Note equal to the reduction in the aggregate principal amount at maturity
of such Regulation S Global Note and to debit or cause to be debited from the
account of the Person making such transfer the beneficial interest in the
Regulation S Global Note that is being transferred.

        (b) Transfer and Exchange of Certificated Notes. When Certificated Notes
are presented by a Holder to the Registrar with a request: to register the
transfer of the Certificated Notes; or to exchange such Certificated Notes for
an equal principal amount of Certificated Notes of other authorized
denominations, the Registrar shall register the transfer or make the exchange as
requested; provided, however, that the Certificated Notes presented or
surrendered for register of transfer or exchange: (i) shall be duly endorsed or
accompanied by a written instruction of transfer in form satisfactory to the
Registrar duly executed by such Holder or by


                                       14
<PAGE>   20
his attorney, duly authorized in writing; and (ii) in the case of a Certificated
Note that is a Restricted Security, such request shall be accompanied by a
Purchaser Letter, in substantially the form of Exhibit B-1 hereto, together with
the following additional information and documents, as applicable: (A) if such
Restricted Security is being delivered to the Registrar by a Holder for
registration in the name of such Holder, without transfer, or such Restricted
Security is being transferred to the Company, a certification to that effect
from such Holder (in substantially the form of Exhibit B-4 hereto); (B) if such
Restricted Security is being transferred to a QIB in accordance with Rule 144A
under the Securities Act or pursuant to an exemption from registration in
accordance with Rule 144 under the Securities Act or pursuant to an effective
registration statement under the Securities Act, a certification to that effect
from such Holder (in substantially the form of Exhibit B-4 hereto); or (C) if
such Restricted Security is being transferred in reliance on any other exemption
from the registration requirements of the Securities Act, a certification to
that effect from such Holder (in substantially the form of Exhibit B-4 hereto)
and an Opinion of Counsel from such Holder or the transferee reasonably
acceptable to the Company and to the Registrar to the effect that such transfer
is in compliance with the Securities Act.

        (c) Transfer of a Beneficial Interest in a Rule 144A Global Note or
Regulation S Global Note for a Certificated Note.

            (i) Any Person having a beneficial interest in a Global Note may
upon request, subject to the Applicable Procedures, exchange such beneficial
interest for a Certificated Note. Upon receipt by the Trustee of written
instructions or such other form of instructions as is customary for the
Depositary (or Euroclear or Clearstream, if applicable), from the Depositary or
its nominee on behalf of any Person having a beneficial interest in a Global
Note, and, in the case of a Restricted Security, a Purchaser Letter, in
substantially the form of Exhibit B-1 hereto, together with the following
additional information and documents, as applicable (all of which may be
submitted by facsimile): (A) if such beneficial interest is being transferred to
the Person designated by the Depositary as being the beneficial owner, a
certification to that effect from such Person (in substantially the form of
Exhibit B-5 hereto); (B) if such beneficial interest is being transferred to a
QIB in accordance with Rule 144A under the Securities Act or pursuant to an
exemption from registration in accordance with Rule 144 under the Securities Act
or pursuant to an effective registration statement under the Securities Act, a
certification to that effect from the transferor (in substantially the form of
Exhibit B-5 hereto); or (C) if such beneficial interest is being transferred in
reliance on any other exemption from the registration requirements of the
Securities Act, a certification to that effect from the transferor (in
substantially the form of Exhibit B-5 hereto) and an Opinion of Counsel from the
transferee or the transferor reasonably acceptable to the Company and to the
Registrar to the effect that such transfer is in compliance with the Securities
Act, in which case the Trustee or the Custodian, at the direction of the
Trustee, shall, in accordance with the standing instructions and procedures
existing between the Depositary and the Custodian, cause the aggregate principal
amount of the applicable Global Notes, to be reduced accordingly and, following
such reduction, the Company shall execute and, the Trustee shall authenticate
and deliver to the transferee a Certificated Note in the appropriate principal
amount.



                                       15
<PAGE>   21

            (ii) Certificated Notes issued in exchange for a beneficial interest
in a Global Note, as applicable, pursuant to this Section 2.6(c) shall be
registered in such names and in such authorized denominations as the Depositary,
pursuant to instructions from its direct or indirect participants or otherwise,
shall instruct the Trustee. Upon execution and authentication, the Trustee shall
deliver such Certificated Notes to the Persons in whose names such Notes are so
registered. Following any such issuance of Certificated Notes, the Trustee, as
Registrar, shall instruct the Depositary to reduce or cause to be reduced the
aggregate principal amount at maturity of the applicable Global Note to reflect
the transfer and an endorsement shall be made on such Security in global form by
the Trustee to reflect such reduction or increase.

        (d) Restrictions on Transfer and Exchange of Global Notes.
Notwithstanding any other provision of this Indenture (other than the provisions
set forth in subsection (f) of this Section 2.6), a Global Note may not be
transferred as a whole except by the Depositary to a nominee of the Depositary
or by a nominee of the Depositary to the Depositary or another nominee of the
Depositary or by the Depositary or any such nominee to a successor Depositary or
a nominee of such successor Depositary.

        (e) Transfer and Exchange of a Certificated Note for a Beneficial
Interest in a Global Note. A Certificated Note may not be transferred or
exchanged for a beneficial interest in a Global Note.

        (f) Authentication of Certificated Notes in Absence of Depositary. If at
any time:

            (i) the Depositary for the Securities notifies the Company that the
Depositary is unwilling or unable to continue as Depositary for the Global Notes
and a successor Depositary for the Global Notes is not appointed by the Company
within 90 days after delivery of such notice; or

            (ii) the Company, at its sole discretion, notifies the Trustee in
writing that it elects to cause the issuance of Certificated Notes under this
Indenture, then the Company shall execute, and the Trustee shall, upon receipt
of an authentication order in accordance with Section 2.2 hereof, authenticate
and deliver, Certificated Notes in an aggregate principal amount equal to the
principal amount of the Global Notes in exchange for such Global Notes.

        (g) Legends.

            (i) Every Security issued by the Company either upon original
issuance or upon registration of transfer or exchange prior to the earlier of
(i) the sale of such Security pursuant to an effective registration statement
under the Securities Act and (ii) the expiration of two years after the date of
original issuance of such Security shall be deemed a Restricted Security. Every
Restricted Security shall be subject to the restrictions on transfer provided in
the legend required to be borne by each Restricted Security pursuant to this
Section 2.6, unless such restrictions on transfer shall be waived by the written
consent of the Company, and the holder of each Restricted Security, by such
Securityholder's acceptance thereof, agrees to be bound by such restrictions on
transfer. Whenever any Restricted Security is presented or surrendered for


                                       16
<PAGE>   22

registration of transfer or for exchange for a Security registered in a name
other than that of the Holder, (i) the notice of assignment set forth in Exhibit
A must be properly completed, dated the date of such surrender and signed by the
Holder of such Restricted Security, and (ii) the Holder of such Restricted
Security shall deliver, prior to such transfer, any other documents required by
the Trustee or the Company pursuant to such notice of assignment, including (A)
in the case of any proposed transfer by a Holder to an Institutional Accredited
Investor, a letter signed by such Institutional Accredited Investor
substantially in the form of Exhibit B-1 relating to certain representations and
agreements regarding restrictions on transfer of such Restricted Security and
(B) in the case of any proposed transfer by a holder to a Person in reliance of
Resolution S, a letter signed by the transferee substantially in the form of
Exhibit B-6 relating to certain representations and agreements regarding
restrictions on transfer of such Restricted Security. The Trustee shall not be
required to accept for such registration of transfer or exchange any Restricted
Security if such conditions in the two preceding sentences have not been
satisfied. Notwithstanding the preceding three sentences, any transfer of an
interest in any Security in global form by a QIB to a QIB through the facilities
of The Depository Trust Company or any other United States securities clearance
and settlement organization may be effected without delivery of any additional
notices or documents to the Trustee or the Company, provided that such transfer
does not require a change in the name (other than to another nominee of The
Depository Trust Company or such other securities clearance and settlement
organization) in which such Security is then registered. The restrictions
imposed by this Section 2.6 upon the transferability of any particular
Restricted Security shall cease and terminate upon the earlier of (i) the sale
of such Restricted Security pursuant to an effective registration statement
under the Securities Act and (ii) the expiration of two years after the date of
original issuance of such Security. The Company shall promptly inform the
Trustee in writing of the effective date of any registration statement
registering the Securities under the Securities Act. Any Security as to which
such restrictions on transfer have expired in accordance with their terms or
have been otherwise terminated may, upon surrender of such Security for exchange
to the Trustee in accordance with the provisions of this Section 2.6, be
exchanged for a new Security, of like tenor and aggregate principal amount,
which shall not bear the restrictive legend required by this Section 2.6. The
Trustee shall not be liable for any action taken or omitted to be taken by it in
good faith in accordance with this paragraph.

        As used in this Section 2.6(g), the term "transfer" encompasses any
sale, pledge, transfer or other disposition of any Restricted Security.

        Until the earlier of (i) the sale of such Restricted Security pursuant
to an effective registration statement under the Securities Act and (ii) the
expiration of two years after the date of original issuance of such Restricted
Security,

        (A) any Global Note evidencing such Restricted Security (and all Global
Notes issued in exchange or substitution therefor) shall bear a legend in
substantially the following form (the "Global Note Restricted Securities
Legend"), unless otherwise agreed by the Company (with written notice thereof to
the Trustee):

        THIS SECURITY HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933,
AS AMENDED (THE "SECURITIES ACT"). THE HOLDER HEREOF, BY PURCHASING THIS
SECURITY, AGREES FOR THE BENEFIT OF THE COMPANY



                                       17
<PAGE>   23
THAT THIS SECURITY MAY NOT BE RESOLD, PLEDGED OR OTHERWISE TRANSFERRED (X)
PRIOR TO THE EXPIRATION OF THE HOLDING PERIOD UNDER RULE 144(k) (OR ANY
SUCCESSOR THERETO) UNDER THE SECURITIES ACT WHICH IS APPLICABLE TO THIS SECURITY
OR (Y) BY ANY HOLDER THAT WAS AN "AFFILIATE" (WITHIN THE MEANING OF RULE 144
UNDER THE SECURITIES ACT) OF THE COMPANY AT ANY TIME DURING THE THREE MONTHS
PRECEDING THE DATE OF SUCH TRANSFER, IN EITHER CASE, OTHER THAN (1) TO THE
COMPANY, (2) SO LONG AS THIS SECURITY IS ELIGIBLE FOR RESALE PURSUANT TO RULE
144A UNDER THE SECURITIES ACT ("RULE 144A"), TO A PERSON WHOM THE SELLER
REASONABLY BELIEVES IS A QUALIFIED INSTITUTIONAL BUYER WITHIN THE MEANING OF
RULE 144A, PURCHASING FOR ITS OWN ACCOUNT OR FOR THE ACCOUNT OF A QUALIFIED
INSTITUTIONAL BUYER TO WHOM NOTICE IS GIVEN THAT THE RESALE, PLEDGE OR OTHER
TRANSFER IS BEING MADE IN RELIANCE ON RULE 144A, (3) IN AN OFFSHORE TRANSACTION
(AS DEFINED IN REGULATION S UNDER THE SECURITIES ACT) IN ACCORDANCE WITH
REGULATION S UNDER THE SECURITIES ACT, (4) TO AN INSTITUTION THAT IS AN
"ACCREDITED INVESTOR" AS DEFINED IN RULE 501(a)(1), (2), (3) OR (7) UNDER THE
SECURITIES ACT ("INSTITUTIONAL ACCREDITED INVESTOR") THAT IS ACQUIRING THIS
SECURITY FOR INVESTMENT PURPOSES AND NOT FOR DISTRIBUTION, AND THAT, PRIOR TO
SUCH TRANSFER, DELIVERS TO THE COMPANY AND THE TRUSTEE A SIGNED LETTER
CONTAINING CERTAIN REPRESENTATIONS AND AGREEMENTS RELATING TO THE RESTRICTIONS
ON TRANSFER OF THE SECURITY EVIDENCED HEREBY (THE FORM OF WHICH LETTER MAY BE
OBTAINED FROM THE TRUSTEE), (5) PURSUANT TO AN EXEMPTION FROM REGISTRATION UNDER
THE SECURITIES ACT PROVIDED BY RULE 144 (IF APPLICABLE) UNDER THE SECURITIES ACT
OR (6) PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT,
IN EACH CASE IN ACCORDANCE WITH ANY APPLICABLE SECURITIES LAWS OF ANY STATE OF
THE UNITED STATES. THE HOLDER HEREOF, BY PURCHASING THIS SECURITY, REPRESENTS
AND AGREES FOR THE BENEFIT OF THE COMPANY THAT IT IS (1) A QUALIFIED
INSTITUTIONAL BUYER OR (2) AN INSTITUTIONAL ACCREDITED INVESTOR AND THAT IT IS
HOLDING THIS SECURITY FOR INVESTMENT PURPOSES AND NOT FOR DISTRIBUTION OR (3)
NOT A U.S. PERSON AND IS OUTSIDE THE UNITED STATES WITHIN THE MEANING OF (OR AN
ACCOUNT SATISFYING THE REQUIREMENTS OF PARAGRAPH (k)(2) OF RULE 902 UNDER)
REGULATION S UNDER THE SECURITIES ACT. IN ANY CASE THE HOLDER HEREOF WILL NOT,
DIRECTLY OR INDIRECTLY, ENGAGE IN ANY HEDGING TRANSACTION WITH REGARD TO THIS
SECURITY OR ANY COMMON STOCK ISSUABLE UPON CONVERSION OF THIS SECURITY EXCEPT AS
PERMITTED BY THE SECURITIES ACT.; and

           (B) any Certificated Note evidencing such Restricted Security (and
all securities issued in exchange or substitution therefor, other than Common
Stock, if any, issued upon conversion thereof that shall bear the legend set
forth in Section 2.6(g)(ii), if applicable) shall bear a legend in substantially
the following form (the "Certificated Note Restricted Securities Legend"),
unless otherwise agreed by the Company (with written notice thereof to the
Trustee):



                                       18
<PAGE>   24

        THIS SECURITY HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933,
AS AMENDED (THE "SECURITIES ACT"). THE HOLDER HEREOF, BY PURCHASING THIS
SECURITY, AGREES FOR THE BENEFIT OF THE COMPANY THAT THIS SECURITY MAY NOT BE
RESOLD, PLEDGED OR OTHERWISE TRANSFERRED (X) PRIOR TO THE EXPIRATION OF THE
HOLDING PERIOD UNDER RULE 144(k) (OR ANY SUCCESSOR THERETO) UNDER THE SECURITIES
ACT WHICH IS APPLICABLE TO THIS SECURITY OR (Y) BY ANY HOLDER THAT WAS AN
"AFFILIATE" (WITHIN THE MEANING OF RULE 144 UNDER THE SECURITIES ACT) OF THE
COMPANY AT ANY TIME DURING THE THREE MONTHS PRECEDING THE DATE OF SUCH TRANSFER,
IN EITHER CASE, OTHER THAN (1) TO THE COMPANY, (2) SO LONG AS THIS SECURITY IS
ELIGIBLE FOR RESALE PURSUANT TO RULE 144A UNDER THE SECURITIES ACT ("RULE
144A"), TO A PERSON WHOM THE SELLER REASONABLY BELIEVES IS A QUALIFIED
INSTITUTIONAL BUYER WITHIN THE MEANING OF RULE 144A, PURCHASING FOR ITS OWN
ACCOUNT OR FOR THE ACCOUNT OF A QUALIFIED INSTITUTIONAL BUYER TO WHOM NOTICE IS
GIVEN THAT THE RESALE, PLEDGE OR OTHER TRANSFER IS BEING MADE IN RELIANCE ON
RULE 144A (AS INDICTED BY THE BOX CHECKED BY THE TRANSFEROR ON THE CERTIFICATE
OF TRANSFER ON THE REVERSE OF THIS SECURITY), (3) IN AN OFFSHORE TRANSACTION (AS
DEFINED IN REGULATION S UNDER THE SECURITIES ACT) IN ACCORDANCE WITH REGULATION
S UNDER THE SECURITIES ACT (AS INDICATED BY THE BOX CHECKED BY THE TRANSFEROR ON
THE CERTIFICATE OF TRANSFER ON THE REVERSE OF THIS SECURITY), (4) TO AN
INSTITUTION THAT IS AN "ACCREDITED INVESTOR" AS DEFINED IN RULE 501(a)(1), (2),
(3) or (7) UNDER THE SECURITIES ACT ("INSTITUTIONAL ACCREDITED INVESTOR") (AS
INDICATED BY THE BOX CHECKED BY THE TRANSFEROR ON THE CERTIFICATE OF TRANSFER ON
THE REVERSE OF THIS SECURITY) THAT IS ACQUIRING THIS SECURITY FOR INVESTMENT
PURPOSES AND NOT FOR DISTRIBUTION, AND THAT, PRIOR TO SUCH TRANSFER, DELIVERS TO
THE COMPANY AND THE TRUSTEE A SIGNED LETTER CONTAINING CERTAIN REPRESENTATIONS
AND AGREEMENTS RELATING TO THE RESTRICTIONS ON TRANSFER OF THE SECURITY
EVIDENCED HEREBY (THE FORM OF WHICH LETTER MAY BE OBTAINED FROM THE TRUSTEE),
(5) PURSUANT TO AN EXEMPTION FROM REGISTRATION UNDER THE SECURITIES ACT PROVIDED
BY RULE 144 (IF APPLICABLE) UNDER THE SECURITIES ACT (AS INDICATED BY THE BOX
CHECKED BY THE TRANSFEROR ON THE CERTIFICATE OF TRANSFER ON THE REVERSE OF THIS
SECURITY) OR (6) PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER THE
SECURITIES ACT, IN EACH CASE ACCORDANCE WITH ANY APPLICABLE SECURITIES LAWS OF
ANY STATE OF THE UNITED STATES. PRIOR TO A TRANSFER OF THIS SECURITY (OTHER THAN
A TRANSFER PURSUANT TO CLAUSE (6) ABOVE), THE HOLDER OF THIS SECURITY MUST,
PRIOR TO SUCH TRANSFER, FURNISH TO THE COMPANY AND THE TRUSTEE SUCH CERTIFICATES
AND OTHER INFORMATION AND, IN THE CASE OF A TRANSFER PURSUANT TO CLAUSE (5)
ABOVE, A LEGAL OPINION AS THEY MAY REASONABLY REQUIRE TO CONFIRM THAT ANY
TRANSFER BY IT OF THIS SECURITY COMPLIES WITH THE FOREGOING RESTRICTIONS. THE
HOLDER HEREOF, BY PURCHASING THIS SECURITY, REPRESENTS AND AGREES FOR THE
BENEFIT OF THE COMPANY THAT



                                       19
<PAGE>   25

IT IS (1) A QUALIFIED INSTITUTIONAL BUYER OR (2) AN INSTITUTIONAL ACCREDITED
INVESTOR AND THAT HOLDING THIS SECURITY FOR INVESTMENT PURPOSES AND NOT FOR
DISTRIBUTION OR (3) NOT A U.S. PERSON AND IS OUTSIDE THE UNITED STATES WITHIN
THE MEANING OF (OR AN ACCOUNT SATISFYING THE REQUIREMENTS OF PARAGRAPH (k)(2) OF
RULE 902) UNDER REGULATION S UNDER THE SECURITIES ACT. IN ANY CASE THE HOLDER
HEREOF WILL NOT, DIRECTLY OR INDIRECTLY, ENGAGE IN ANY HEDGING TRANSACTION WITH
REGARD TO THIS SECURITY OR ANY COMMON STOCK ISSUABLE UPON CONVERSION OF THIS
SECURITY EXCEPT AS PERMITTED BY THE SECURITIES ACT.

        The Depositary shall be a clearing agency registered under the Exchange
Act. The Company initially appoints The Depository Trust Company to act as
Depositary with respect to the Securities in global form. Initially, the Global
Note shall be issued to the Depositary, registered in the name of Cede & Co., as
the nominee of the Depositary, and deposited with the custodian for Cede & Co.

        If a definitive Security is issued in exchange for any portion of a
Security in global form after the close of business at the office or agency
where such exchange occurs on any record date and before the opening of business
at such office or agency on the next succeeding interest payment date, interest
will not be payable on such interest payment date in respect of such Security,
but will be payable on such interest payment date only to the person to whom
interest in respect of such portion of such Security in global form is payable
in accordance with the provisions of this Indenture.

            (ii) Until two years after the original issuance date of any
Security, any stock certificate representing Common Stock issued upon conversion
of such Security shall bear a legend in substantially the following form (the
"Restricted Stock Legend"), unless otherwise agreed by the Company (with written
notice thereof to the Trustee):

        THIS SECURITY HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933,
AS AMENDED (THE "SECURITIES ACT"). THE HOLDER HEREOF, BY PURCHASING THIS
SECURITY, AGREES FOR THE BENEFIT OF THE COMPANY THAT THIS SECURITY MAY NOT BE
RESOLD, PLEDGED OR OTHERWISE TRANSFERRED (X) PRIOR TO THE EXPIRATION OF THE
HOLDING PERIOD UNDER RULE 144(k) (OR ANY SUCCESSOR THERETO) UNDER THE SECURITIES
ACT WHICH IS APPLICABLE TO THIS SECURITY OR (Y) BY ANY HOLDER THAT WAS AN
"AFFILIATE" (WITHIN THE MEANING OF RULE 144 UNDER THE SECURITIES ACT) OF THE
COMPANY AT ANY TIME DURING THE THREE MONTHS PRECEDING THE DATE OF SUCH TRANSFER,
IN EITHER CASE, OTHER THAN (1) TO THE COMPANY, (2) IN AN OFFSHORE TRANSACTION
(AS DEFINED IN REGULATION S UNDER THE SECURITIES ACT) IN ACCORDANCE WITH
REGULATION S UNDER THE SECURITIES ACT (AS INDICATED BY THE BOX CHECKED BY THE
TRANSFEROR ON THE CERTIFICATE OF TRANSFER APPLICABLE TO THIS SECURITY, THE FORM
OF WHICH MAY BE OBTAINED FROM THE COMPANY OR THE TRANSFER AGENT), (3) TO AN
INSTITUTION THAT IS AN "ACCREDITED INVESTOR" AS DEFINED IN RULE 501(a)(1), (2),
(3) OR (7) UNDER THE SECURITIES ACT ("INSTITUTIONAL



                                       20
<PAGE>   26

ACCREDITED INVESTOR") (AS INDICATED BY THE BOX CHECKED BY THE TRANSFEROR ON THE
CERTIFICATE OF TRANSFER APPLICABLE TO THIS SECURITY, THE FORM OF WHICH MAY BE
OBTAINED FROM THE COMPANY OR THE TRANSFER AGENT) THAT IS ACQUIRING THIS SECURITY
FOR INVESTMENT PURPOSES AND NOT FOR DISTRIBUTION, AND THAT PRIOR TO SUCH
TRANSFER, DELIVERS TO THE COMPANY AND THE TRANSFER AGENT A SIGNED LETTER
CONTAINING CERTAIN REPRESENTATIONS AND AGREEMENTS RELATING TO THE RESTRICTIONS
ON TRANSFER OF THE SECURITY EVIDENCED HEREBY (THE FORM OF WHICH LETTER MAY BE
OBTAINED FROM THE COMPANY OR THE TRANSFER AGENT), (4) PURSUANT TO AN EXEMPTION
FROM REGISTRATION UNDER THE SECURITIES ACT PROVIDED BY RULE 144 (IF APPLICABLE)
UNDER THE SECURITIES ACT (AS INDICATED BY THE BOX CHECKED BY THE TRANSFEROR ON
THE CERTIFICATE OF TRANSFER APPLICABLE TO THIS SECURITY, THE FORM OF WHICH MAY
BE OBTAINED FROM THE COMPANY OR THE TRANSFER AGENT) OR (5) PURSUANT TO AN
EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT, IN EACH CASE IN
ACCORDANCE WITH ANY APPLICABLE SECURITIES LAWS OF ANY STATE OF THE UNITED
STATES, PRIOR TO A TRANSFER OF THIS SECURITY (OTHER THAN A TRANSFER PURSUANT TO
CLAUSE (5) ABOVE), THE HOLDER OF THIS SECURITY MUST, PRIOR TO SUCH TRANSFER,
FURNISH TO THE COMPANY AND THE TRANSFER AGENT SUCH CERTIFICATES AND OTHER
INFORMATION AND, IN THE CASE OF A TRANSFER PURSUANT TO CLAUSE (4) ABOVE, A LEGAL
OPINION AS THEY MAY REASONABLY REQUIRE TO CONFIRM THAT ANY TRANSFER BY IT OF
THIS SECURITY COMPLIES WITH THE FOREGOING RESTRICTIONS. THE HOLDER HEREOF, BY
PURCHASING THIS SECURITY, REPRESENTS AND AGREES FOR THE BENEFIT OF THE COMPANY
THAT IT IS (1) AN INSTITUTION THAT IS AN "ACCREDITED INVESTOR" AS DEFINED IN
RULE 501(a)(1), (2), (3) OR (7) UNDER THE SECURITIES ACT AND THAT IT IS HOLDING
THIS SECURITY FOR INVESTMENT PURPOSES AND NOT FOR DISTRIBUTION OR (2) NOT A U.S.
PERSON AND IS OUTSIDE THE UNITED STATES WITHIN THE MEANING OF (OR AN ACCOUNT
SATISFYING THE REQUIREMENTS OF PARAGRAPH (k)(2) OF RULE 902 UNDER) REGULATION S
UNDER THE SECURITIES ACT. IN ANY CASE THE HOLDER HEREOF WILL NOT, DIRECTLY OR
INDIRECTLY, ENGAGE IN ANY HEDGING TRANSACTION WITH REGARD TO THIS SECURITY
EXCEPT AS PERMITTED BY THE SECURITIES ACT.

            (iii) Any certificate evidencing a Security that has been
transferred to an Affiliate of the Company within two years after the original
issuance date of the Security, as evidenced by a notation on the Assignment Form
for such transfer or in the representation letter delivered in respect thereof,
shall, until two years after the last date on which the Company or any Affiliate
of the Company was an owner of such Security, bear a legend in substantially the
following form (the "Affiliate Legend"), unless otherwise agreed by the Company
(with written notice thereof to the Trustee);

        THE SECURITY EVIDENCED HEREBY HAS NOT BEEN REGISTERED UNDER THE U.S.
SECURITIES ACT OF 1933, AS AMENDED (THE "SECURITIES ACT"), AND, ACCORDINGLY, MAY
NOT BE OFFERED OR SOLD WITHIN THE UNITED STATES OR



                                       21
<PAGE>   27

TO, OR FOR THE ACCOUNT OR BENEFIT OF, U.S. PERSONS EXCEPT AS SET FORTH IN THE
FOLLOWING SENTENCE. BY ITS ACQUISITION HEREOF, THE HOLDER AGREES (1) THAT IT
WILL NOT RESELL OR OTHERWISE TRANSFER THE SECURITY EVIDENCED HEREBY OR THE
COMMON STOCK ISSUABLE UPON CONVERSION OF SUCH SECURITY EXCEPT (A) TO INCYTE
PHARMACEUTICALS, INC. OR ANY SUBSIDIARY THEREOF, (B) IN A TRANSACTION REGISTERED
UNDER THE SECURITIES ACT OR (C) PURSUANT TO THE EXEMPTION FROM REGISTRATION
PROVIDED BY RULE 144 UNDER THE SECURITIES ACT (IF AVAILABLE) AND (2) THAT IT
WILL DELIVER TO EACH PERSON TO WHOM THE SECURITY EVIDENCED HEREBY IS TRANSFERRED
A NOTICE SUBSTANTIALLY TO THE EFFECT OF THIS LEGEND. IF THE PROPOSED TRANSFER IS
PURSUANT TO THE EXEMPTION FROM REGISTRATION PROVIDED BY RULE 144 UNDER THE
SECURITIES ACT, THE HOLDER MUST, PRIOR TO SUCH TRANSFER, FURNISH TO STATE STREET
BANK AND TRUST COMPANY OF CALIFORNIA, N.A., AS TRUSTEE (OR A SUCCESSOR TRUSTEE,
IF APPLICABLE), SUCH CERTIFICATIONS, LEGAL OPINIONS OR OTHER INFORMATION AS THE
COMPANY MAY REASONABLY REQUIRE TO CONFIRM THAT SUCH TRANSFER IS BEING MADE
PURSUANT TO AN EXEMPTION FROM, OR IN A TRANSACTION NOT SUBJECT TO, THE
REGISTRATION REQUIREMENTS OF THE SECURITIES ACT. AS USED HEREIN, THE TERMS
"UNITED STATES" AND "U.S. PERSON" HAVE THE MEANINGS GIVEN TO THEM BY REGULATION
S UNDER THE SECURITIES ACT.

Any stock certificate representing Common Stock issued upon conversion of a
Security that has been transferred to an Affiliate of the Company within two
years after the original issuance date of the Security, as evidenced by a
notation on the Assignment Form for such transfer or in the representation
letter delivered in respect thereof, shall also bear a legend in substantially
the form indicated above, unless otherwise agreed by the Company (with written
notice thereof to the Trustee).

           (iv) Upon any sale or transfer of a Restricted Security (including
any Restricted Security represented by a Global Note) pursuant to Rule 144 under
the Securities Act or pursuant to an effective registration statement under the
Securities Act:

                (A) in the case of any Restricted Security that is a
Certificated Note, the Registrar shall permit the Holder thereof to exchange
such Restricted Security for a Certificated Note that does not bear the legend
set forth in (i) above and rescind any restriction on the transfer of such
Restricted Security upon receipt of a certification from the transferring Holder
substantially in the form of Exhibit B-5 hereto; and

                (B) in the case of any Restricted Security represented by a
Global Note, such Restricted Security shall not be required to bear the legend
set forth in (i) above, but shall continue to be subject to the provisions of
Section 2.6(a) and (d) hereof; provided, however, that with respect to any
request for an exchange of a Restricted Security that is represented by a Global
Note for a Certificated Note that does not bear the legend set forth in (i)
above, which request is made in reliance upon Rule 144, the Holder thereof shall
certify in writing to the Registrar that such request is being made pursuant to
Rule 144 (such certification to be substantially in the form of Exhibit B-5
hereto).



                                       22
<PAGE>   28

        (v) Upon any sale or transfer of a Restricted Security (including any
Restricted Security represented by a Global Note) in reliance on any exemption
from the registration requirements of the Securities Act (other than exemptions
pursuant to Rule 144A or Rule 144 under the Securities Act) in which the Holder
or the transferee provides an Opinion of Counsel to the Company and the
Registrar in form and substance reasonably acceptable to the Company and the
Registrar (which Opinion of Counsel shall also state that the transfer
restrictions contained in the legend are no longer applicable):

               (A) in the case of any Restricted Security that is a Certificated
Note, the Registrar shall permit the Holder thereof to exchange such Restricted
Security for a Certificated Note that does not bear the legend set forth in (i)
above and rescind any restriction on the transfer of such Restricted Security;
and

               (B) in the case of any Restricted Security represented by a
Global Note, such Restricted Security shall not be required to bear the legend
set forth in (i) above, but shall continue to be subject to the provisions of
Section 2.6(a) and (d) hereof.

        (h) Notwithstanding any provision of Section 2.5 to the contrary, in the
event Rule 144(k) as promulgated under the Securities Act (or any successor
rule) is amended to shorten the two-year period under Rule 144(k) (or the
corresponding period under any successor rule), then in that event, from and
after receipt by the Trustee of the Officers' Certificate and Opinion of Counsel
provided for in this Section 2.6(h), (1) the references in the first and sixth
sentences of the first paragraph of Section 2.6(g)(i) to "two years" shall be
deemed for all purposes hereof to be references to such shorter period, (2) the
references in the first sentence each of Sections 2.6(g)(ii) and (iii) and the
last sentence of Section 2.6(g)(iii) to "two years" shall be deemed for all
purposes hereof to be references to such shorter period, (3) the reference in
the last sentence of Section 6.2 to "two years" shall be deemed for all purposes
hereof to be a reference to such shorter period, and (4) all corresponding
references in the Securities and the restrictive legends thereon (including the
restrictive legends on any Common Stock issuable upon conversion of the
Securities) shall be deemed for all purposes hereof to be references to such
shorter period, provided that such changes shall not become effective if they
are otherwise prohibited by, or would otherwise cause a violation of, the
then-applicable federal securities laws. As soon as practicable after the
Company has knowledge of the effectiveness of any such amendment to shorten the
two-year period under Rule 144(k) (or the corresponding period under any
successor rule, unless such changes would otherwise be prohibited by, or would
otherwise cause a violation of, the then-applicable federal securities law, the
Company shall provide to the Trustee an Officers' Certificate and Opinion of
Counsel informing the Trustee of the effectiveness of such amendment and the
effectiveness of the foregoing changes to Sections 2.6(g) and 6.2. This Section
2.6(h) shall apply to successive amendments to Rule 144(k) (or any successor
rule) shortening the holding period thereunder.

        (i) Cancellation and/or Adjustment of Global Notes. At such time as all
beneficial interests in Global Notes have been exchanged for Certificated Notes,
redeemed, repurchased or cancelled, all Global Notes shall be returned to or
retained and cancelled by the Trustee in accordance with Section 2.11 hereof. At
any time prior to such cancellation, if any beneficial interest in a Global Note
is exchanged for Certificated Notes, redeemed, repurchased or cancelled, the
principal amount of Securities represented by such Global Note shall be reduced


                                       23
<PAGE>   29

accordingly and an endorsement shall be made on such Global Note, by the Trustee
or the Custodian, at the direction of the Trustee, to reflect such reduction.

        (j) General Provisions Relating to Transfers and Exchanges.

            (i) To permit registrations of transfers and exchanges, the Company
shall execute and the Trustee shall authenticate Certificated Notes and Global
Notes at the Registrar's request.

            (ii) No service charge shall be made to a Holder for any
registration of transfer or exchange, but the Company may require payment of a
sum sufficient to cover any transfer tax or similar governmental charge payable
in connection therewith (other than any such transfer taxes or similar
governmental charge payable upon exchange or transfer pursuant to Sections 3.9,
4.10, 4.15 and 9.5 hereto).

            (iii) The Registrar shall not be required to register the transfer
of or exchange any Security selected for redemption in whole or in part, except
the unredeemed portion of any Security being redeemed in part.

            (iv) All Certificated Notes and Global Notes issued upon any
registration of transfer or exchange of Certificated Notes or Global Notes shall
be the valid obligations of the Company, evidencing the same debt, and entitled
to the same benefits under this Indenture, as the Certificated Notes or Global
Notes surrendered upon such registration of transfer or exchange.

            (v) The Company shall not be required:

                (A) to issue, to register the transfer of or to exchange
Securities during a period beginning at the opening of business 15 days before
the day of any selection of Securities for redemption under Section 3.2 hereof
and ending at the close of business on the day of selection; or

                (B) to register the transfer of or to exchange any Security so
selected for redemption in whole or in part, except the unredeemed portion of
any Security being redeemed in part; or

                (C) to register the transfer of or to exchange a Security
between a record date and the next succeeding interest payment date.

        (vi) Prior to due presentment for the registration of a transfer of any
Security, the Trustee, any Agent and the Company may deem and treat the Person
in whose name any Security is registered as the absolute owner of such Security
for the purpose of receiving payment of principal of and interest on such
Securities, and neither the Trustee, any Agent nor the Company shall be affected
by notice to the contrary.

        (vii) The Trustee shall authenticate Certificated Notes and Global Notes
in accordance with the provisions of Section 2.2 hereof.



                                       24
<PAGE>   30

SECTION 2.7 REPLACEMENT SECURITIES.

        If any mutilated Security is surrendered to the Company or the Trustee,
or the Company and the Trustee receive evidence to their satisfaction of the
destruction, loss or theft of any Security, and there is delivered to the
Company and the Trustee such Security or indemnity as may be required by them to
save each of them harmless, then, in the absence of notice to the Company or the
Trustee that such Security has been acquired by a bona fide purchaser, the
Company shall execute, and upon its written request the Trustee shall
authenticate and deliver, in exchange for any such mutilated Security or in lieu
of any such destroyed, lost or stolen Security, a new Security of like tenor and
principal amount, bearing a number not contemporaneously outstanding.

        In case any such mutilated, destroyed, lost or stolen Security has
become or is about to become due and payable, or is about to be redeemed by the
Company pursuant to Article 3, the Company in its discretion may, instead of
issuing a new Security, pay or redeem such Security, as the case may be.

        Upon the issuance of any new Securities under this Section 2.7, the
Company may require the payment of a sum sufficient to cover any tax or other
governmental charge that may be imposed in relation thereto and any other
expenses (including the fees and expenses of the Trustee) in connection
therewith.

        Every new Security issued pursuant to this Section 2.7 in lieu of any
destroyed, lost or stolen Security shall constitute an original additional
contractual obligation of the Company, whether or not the destroyed, lost or
stolen Security shall be at any time enforceable by anyone, and shall be
entitled to all benefits of this Indenture equally and proportionately with any
and all other Securities duly issued hereunder.

        The provisions of this Section 2.7 are exclusive and shall preclude (to
the extent lawful) all other rights and remedies with respect to the replacement
or payment of mutilated, destroyed, lost or stolen Securities.

SECTION 2.8 OUTSTANDING SECURITIES.

        Securities outstanding at any time are all Securities authenticated by
the Trustee, except for those canceled by it, those delivered to it for
cancellation and those described in this Section 2.8 as not outstanding.

        If a Security is replaced pursuant to Section 2.7, it ceases to be
outstanding unless the Trustee receives proof satisfactory to it that the
replaced Security is held by a bona fide purchaser.

        If the Paying Agent (other than the Company or an Affiliate of the
Company) holds on a redemption date, repurchase date or maturity date money
sufficient to pay the principal of, premium, if any (including the Make-Whole
Payment, if any), and accrued interest on Securities payable on that date, then
on and after that date such Securities cease to be outstanding and interest on
them ceases to accrue.



                                       25
<PAGE>   31

        Subject to the restrictions contained in Section 2.9, a Security does
not cease to be outstanding because the Company or an Affiliate of the Company
holds the Security.

SECTION 2.9 TREASURY SECURITIES.

        In determining whether the Holders of the required principal amount of
Securities have concurred in any notice, direction, waiver or consent,
Securities owned by the Company or any other obligor on the Securities or by any
Affiliate of the Company or of such other obligor shall be disregarded, except
that for purposes of determining whether the Trustee shall be protected in
relying on any such notice, direction, waiver or consent, only Securities which
the Trustee knows are so owned shall be so disregarded. Securities so owned
which have been pledged in good faith shall not be disregarded if the pledgee
establishes to the satisfaction of the Trustee the pledgee's right so to act
with respect to the Securities and that the pledgee is not the Company or any
other obligor upon the Securities or any Affiliate of the Company or of such
other obligor.

SECTION 2.10 TEMPORARY SECURITIES.

        Until definitive Securities are ready for delivery, the Company may
prepare and execute, and, upon the order of the Company, the Trustee shall
authenticate and deliver temporary Securities. Temporary Securities shall be
substantially in the form of definitive Securities but may have variations that
the Company with the consent of the Trustee considers appropriate for temporary
Securities. Every such temporary Security shall be executed by the Company and
authenticated by the Trustee upon the same conditions and in substantially the
same manner, and with the same effect, as the definitive Securities. Without
unreasonable delay the Company will execute and deliver to the Trustee
definitive Securities and thereupon any or all temporary Securities may be
surrendered in exchange therefor, at each office or agency maintained by the
Company pursuant to Section 5.2 and the Trustee shall authenticate and deliver
in exchange for such temporary Securities an equal aggregate principal amount at
maturity of definitive Securities. Such exchange shall be made by the Company at
its own expense and without any charge therefor. Until so exchanged, the
temporary Securities shall in all respects be entitled to the same benefits
under this Indenture as definitive Securities authenticated and delivered
hereunder.

SECTION 2.11 CANCELLATION.

        The Company at any time may deliver Securities to the Trustee for
cancellation. The Registrar, the Paying Agent and the Conversion Agent shall
forward to the Trustee any Securities surrendered to them for transfer,
exchange, payment or conversion. The Trustee and no one else shall cancel all
Securities surrendered for transfer, exchange, payment (including redemption or
repurchase), conversion or cancellation and shall destroy cancelled Securities
and thereupon deliver a certificate of cancellation to the Company. The Company
may not issue new Securities to replace Securities it has paid or delivered to
the Trustee for cancellation or which have been converted.



                                       26
<PAGE>   32

SECTION 2.12 CUSIP NUMBERS.

        The Company in issuing the Securities may use "CUSIP" numbers (if then
generally in use), and if so, the Trustee shall use "CUSIP" numbers in notices
of redemption as a convenience to Holders; provided, that any such notice may
state that no representation is made as to the correctness of such numbers
either as printed on the Securities or as contained in any notice of a
redemption and that reliance may be placed only on the other identification
numbers printed on the Securities, and any such redemption shall not be affected
by any defect in or omission of such numbers. The Company will promptly notify
the Trustee of any change in the "CUSIP" numbers.

                                   ARTICLE 3.

                            REDEMPTION AND REPURCHASE

SECTION 3.1 RIGHT OF PROVISIONAL REDEMPTION.

        The Securities may be redeemed by the Company (a "Provisional
Redemption"), in whole or in part, at any time prior to February 7, 2003, upon
notice as set forth in Section 3.5 at a redemption price equal to $1,000 per
Security to be redeemed plus accrued and unpaid interest, if any (including
Additional Interest, if any), to the date of redemption (the "Provisional
Redemption Date") if (i) the closing price of the Common Stock shall have
exceeded 150% of the conversion price then in effect for at least 20 Trading
Days in any consecutive 30-Trading Day period ending on the Trading Day prior to
the date of mailing of the notice of redemption pursuant to Section 3.5 (the
"Redemption Notice Date") and (ii) the Shelf Registration Statement is effective
and available for use and is expected to remain effective and available for use
for the 30 days immediately following the Provisional Redemption Date. Upon any
such Provisional Redemption, the Company shall make an additional payment in
cash (the "Make-Whole Payment") with respect to the Securities called for
redemption to Holders on the Redemption Notice Date in an amount equal to $165
per $1,000 Security, less the amount of any interest actually paid on such
Security prior to the Redemption Notice Date. The Company shall make the
Make-Whole Payment on all Securities called for Provisional Redemption,
including any Securities converted into Common Stock pursuant to the terms
hereof after the Redemption Notice Date and prior to the third business day
prior to the Provisional Redemption Date.

SECTION 3.2 RIGHT OF OPTIONAL REDEMPTION.

        The Company may, at its option, redeem (an "Optional Redemption") all or
from time to time any part of the Securities on any date on or after February 7,
2003 and prior to maturity, upon notice as set forth in Section 3.5, and at the
redemption prices set forth in paragraph 6 of the form of Security attached
hereto as Exhibit A, together with accrued interest to the date of redemption.

SECTION 3.3 ELECTION TO REDEEM; NOTICE TO TRUSTEE.

        If the Company elects to redeem Securities pursuant to paragraph 5 or 6
of the Securities, it shall notify the Trustee at least 60 days prior to the
redemption date as fixed by the Company (unless a shorter notice shall be
satisfactory to the Trustee) of the redemption date and the principal amount of
Securities to be redeemed. If fewer than all of the Securities are to be



                                       27
<PAGE>   33
redeemed, the record date relating to such redemption shall be selected by the
Company and given to the Trustee, which record date shall not be less than 10
days after the date of notice to the Trustee.

SECTION 3.4 SELECTION OF SECURITIES TO BE REDEEMED.

        If less than all of the Securities are to be redeemed, the Trustee
shall, not more than 60 days prior to the redemption date, select the Securities
to be redeemed by lot, pro rata or by another method the Trustee considers fair
and appropriate; provided that such method is not prohibited by any stock
exchange or market on which the Securities are then listed. The Trustee shall
make the selection from the Securities outstanding and not previously called for
redemption. Securities in denominations of $1,000 may only be redeemed in whole.
The Trustee may select for redemption portions (equal to $1,000 or any multiple
thereof) of the principal of Securities that have denominations larger than
$1,000. Provisions of this Indenture that apply to Securities called for
redemption also apply to portions of Securities called for redemption.

SECTION 3.5 NOTICE OF REDEMPTION.

        At least 20 days but not more than 60 days before a redemption date, the
Company shall mail or cause to be mailed a notice of redemption by first-class
mail to each Holder of Securities to be redeemed at such Holder's address as it
appears on the Registrar's books.

        The notice shall identify the Securities to be redeemed and shall state:

        (1) the redemption date;

        (2) the redemption price;

        (3) the then current conversion price;

        (4) whether such redemption is a Provisional Redemption or an Optional
Redemption;

        (5) if such redemption is a Provisional Redemption, the Make-Whole
Amount;

        (6) the name and address of the Paying Agent and the Conversion Agent;

        (7) that Securities called for redemption must be presented and
surrendered to the Paying Agent to collect the redemption price;

        (8) that the Securities called for redemption may be converted at any
time before the close of business on the third business day immediately
preceding the redemption date;

        (9) that Holders who wish to convert Securities must satisfy the
requirements in paragraph 9 of the Securities;



                                       28
<PAGE>   34

        (10) that, unless the Company defaults in making the redemption payment,
interest on Securities called for redemption ceases to accrue on and after the
redemption date and the only remaining right of the Holder is to receive payment
of the redemption price upon presentation and surrender to the Paying Agent of
the Securities;

        (11) if any Security is being redeemed in part, the portion of the
principal amount of such Security to be redeemed and that, after the redemption
date, upon presentation and surrender of such Security, a new Security or
Securities in principal amount equal to the unredeemed portion thereof will be
issued; and

        (12) the CUSIP number of the Securities called for redemption.

        At the Company's request, the Trustee shall give the notice of
redemption in the Company's name and at the Company's expense.

SECTION 3.6 DEPOSIT OF REDEMPTION PRICE.

        On or prior to any Redemption Date, the Company shall deposit with the
Trustee or with a Paying Agent (or, if the Company is acting as its own Paying
Agent, segregate and hold in trust) (i) an amount of money sufficient to pay the
Redemption Price of, and (except if the Redemption Date shall be an interest
payment date) accrued interest on, all the Securities which are to be redeemed
on that date other than any Securities called for redemption on that date which
have been converted prior to the date of such deposit and (ii) with respect to
Securities called for Provisional Redemption pursuant to Section 3.1, an amount
or money sufficient to pay the Make-Whole Payment for al the Securities (or
portions thereof) called for redemption (including those surrendered for
conversion into Common Stock after the Redemption Notice Date and prior to the
provisional Redemption Date); provided that if such payment is made on the
Redemption Date, it must be received by the Trustee or Paying Agent, as the case
may be, by 10:00 a.m. New York City time on such date.

        If any Security called for redemption is converted, any money deposited
with the Trustee or with any Paying Agent or segregated and held in trust for
the redemption of such Security shall (subject to any right of the Holder of
such Security or any predecessor security to receive interest) be paid to the
Company as soon as practicable upon written request by the Company or, if then
held by the Company, shall be released from such trust; provided that, with
respect to a Provisional Redemption, any money so deposited for payment of the
Make-Whole Payment shall remain segregated and held in trust for payment of the
Make-Whole Payment which shall be made on all Securities called for Provisional
Redemption, including Securities converted into Common Stock after the
Redemption Notice Date and prior to the third Business Day prior to the
Provisional Redemption Date.

SECTION 3.7 SECURITIES PAYABLE ON REDEMPTION DATE.

        Notice of redemption having been given as aforesaid, the Securities so
to be redeemed shall, on the Redemption Date, become due and payable at the
Redemption Price therein specified, and with respect to Securities called for
Provisional Redemption, the Make-Whole Payment, and from and after such date
(unless the Company shall default in the payment of the



                                       29
<PAGE>   35

Redemption Price and accrued interest or the Make-Whole Payment, if any) such
Securities shall cease to bear or accrue any interest. Upon surrender of any
such Security for redemption in accordance with said notice, such Security shall
be paid by the Company at the Redemption Price, together with accrued interest
to (but not including) the Redemption Date and, with respect to Securities
called for Provisional Redemption (including Securities converted into Common
Stock pursuant to the terms hereof after the Redemption Notice Date and prior to
the third business day prior to the Provisional Redemption Date), the Make-Whole
Payment; provided, however, that installments of interest whose stated maturity
is on or prior to the Redemption Date shall be payable to the Holders of such
Securities registered as such at the close of business on the relevant Record
Dates according to their terms; and provided further that, with respect to a
Provisional Redemption, the holder of any securities converted into Common Stock
pursuant to the terms of this Indenture after the Redemption Notice Date and
prior to the third Business Day prior to the Provisional Redemption Date shall
have the right to the Make-Whole Payment, if any, with respect to such
Securities regardless of the conversion of such Securities.

        If the Company shall fail to deposit the Redemption Price (and
Make-Whole Payment, if any) with the Trustee and any security called for
redemption shall not be so paid upon surrender thereof for redemption, the
principal and premium, if any (including the Make-Whole Payment, if any), shall,
until paid, bear and accrue interest from the Redemption Date at the rate borne
by the Security.

SECTION 3.8 SECURITIES REDEEMED IN PART.

        Any Security which is to be redeemed only in part shall be surrendered
at an office or agency of the Company designated for that purpose (with, if the
Company or the Trustee so requires, due endorsement by, or a written instrument
of transfer in form satisfactory to the Company and the Trustee duly executed
by, the Holder thereof or his attorney-in-fact duly authorized in writing), and
the Company shall execute, and the Trustee shall authenticate and deliver to the
Holder of such Security without service charge, a new Security or Securities, of
any authorized denomination as requested by such Holder, in aggregate principal
amount equal to and in exchange for the unredeemed portion of the principal
amount of the Security so surrendered.

SECTION 3.9 CONVERSION ARRANGEMENT ON CALL FOR REDEMPTION.

        In connection with any redemption of Securities, the Company may arrange
for the purchase and conversion of any Securities by an agreement with one or
more investment bankers or other purchasers to purchase such Securities by
paying to the Trustee in trust for the Holders, on or before the Redemption
Date, an amount not less than the applicable Redemption Price of such
Securities, together with interest accrued to the Redemption Date, and, in
connection with a Provisional Redemption, the Make-Whole Payment.
Notwithstanding anything to the contrary contained in this Article 3, the
obligation of the Company to pay the Redemption Price of such Securities,
together with interest accrued to, but excluding, the Redemption Date and, in
connection with a Provisional Redemption, the Make-Whole Payment, shall be
deemed to be satisfied and discharged to the extent such amount is so paid by
such purchasers. If such an agreement is entered into, a copy of which shall be
filed with the Trustee prior to the Redemption Date, any Securities not duly
surrendered for conversion by the Holders thereof, may, at



                                       30
<PAGE>   36
the option of the Company, be deemed, to the fullest extent permitted by law,
acquired by such purchasers from such Holders and (notwithstanding anything to
the contrary contained in Article 4) surrendered by such purchasers for
conversion, all as of immediately prior to the close of business on the
Redemption Date (and the right to convert any such Securities shall be deemed to
have been extended through such time), subject to payment of the above amount as
aforesaid (including the Make-Whole Payment, if any, with respect to all
Securities called for Provisional Redemption). At the direction of the Company,
the Trustee shall hold and dispose of any such amount paid to it in the same
manner as it would monies deposited with it by the Company for the redemption of
Securities. Without the Trustee's prior written consent, no arrangement between
the Company and such purchasers for the purchase and conversion of any
Securities shall increase or otherwise affect any of the powers, duties,
responsibilities or obligations of the Trustee as set forth in this Indenture,
and the Company agrees to indemnify the Trustee from, and hold it harmless
against, any loss, liability or expense arising out of or in connection with any
such arrangement for the purchase and conversion of any Securities between the
Company and such purchasers to which the Trustee has not consented in writing,
including the costs and expenses incurred by the Trustee in the defense of any
claim or liability arising out of or in connection with the exercise or
performance of any of its powers, duties, responsibilities or obligations under
this Indenture. Nothing in the preceding sentence shall be deemed to limit the
rights and protections afforded to the Trustee in Article 9 hereof, including,
but not limited to, the right to the indemnification pursuant to Section 9.7.

SECTION 3.10 REPURCHASE OF SECURITIES AT OPTION OF THE HOLDER UPON CHANGE IN
CONTROL.

        If at any time that Securities remain outstanding there shall have
occurred a Change in Control (as hereinafter defined), Securities shall be
repurchased by the Company at the option of the Holder thereof, at a purchase
price (the "Repurchase Price") equal to the principal amount thereof plus
accrued interest up to and including the Repurchase Date (as hereinafter
defined), on the date (the "Repurchase Date") fixed by the Company that is not
less than 45 days nor more than 60 days after the date of the Company Notice (as
hereinafter defined), subject to satisfaction by or on behalf of the Holder of
the requirements set forth in Section 3.12(b).

        At the option of the Company, the Repurchase Price may be paid in cash
or, subject to the fulfillment by the Company of the conditions set forth in
Section 3.11, by delivery of shares of Common Stock in accordance with Section
3.11. Whenever in this Indenture there is a reference to the principal of any
Security as of any time, such reference shall be deemed to include reference to
the Repurchase Price payable in respect of such Security to the extent that such
Repurchase Price is, was or would be so payable at such time, and express
mention of the Repurchase Price in any provision of this Indenture shall not be
construed as excluding the Repurchase Price in those provisions of this
Indenture when such express mention is not made.

        Any rights of Holders, contractual or otherwise, arising under or
pursuant to any offer to repurchase Securities made by the Company under this
Section 3.10 shall be subordinated in right of payment to all Senior
Indebtedness to the same extent as the Securities are subordinated to Senior
Indebtedness under the provisions of Article 5 and such offer to repurchase
shall provide that, if at the time the Securities are required to be repurchased
pursuant to such offer, payment of the Securities is not permitted pursuant to
the provisions of Article 5, the Company shall use its best efforts to obtain
all necessary waivers from, or to repay in full, the holders of



                                       31
<PAGE>   37
Senior Indebtedness in order to permit such repurchase. Notwithstanding the
foregoing, any failure by the Company to comply with this Section 3.10 to offer
to repurchase, or to repurchase, the Securities shall be a default in the
performance by the Company hereunder.

        A "Change in Control" shall be deemed to have occurred at such time
after the original issuance of the Securities as any of the following occur:

        (1) a "person" or "group" (within the meaning of Sections 13(d) and
14(d) of the Exchange Act) is or becomes the "beneficial owner" (as defined in
Rule 13d-3 under the Exchange Act, except that a person shall be deemed to be
the "beneficial owner" of all securities that such person has the right to
acquire, whether such right is exercisable immediately or only after the passage
of time), directly or indirectly, of more than 50% of the total voting power of
all outstanding Voting Shares;

        (2) the Company shall consolidate with or merge into any other Person or
sell, convey, transfer or lease all or substantially all of its properties and
assets to any Person other than a Subsidiary, or any other Person shall
consolidate with or merge into the Company (other than, in the case of this
clause 3.10(2), pursuant to any consolidation or merger where Persons who are
shareholders of the Company immediately prior thereto become the Beneficial
Owners of shares of capital stock of the surviving company entitling such
Persons to exercise more than 50% of the total voting power of all classes of
such surviving company's capital stock entitled to vote generally in the
election of directors).

        (3) a change in the Board of Directors of the Company in which the
individuals who constituted the Board of Directors of the Company at the
beginning of the two-year period immediately preceding such change (together
with any other director whose election by the Board of Directors of the Company
or whose nomination for election by the stockholders of the Company was approved
by a vote of at least a majority of the directors then in office either who were
directors at the beginning of such period or whose election or nomination for
election was previously so approved) cease for any reason to constitute a
majority of the directors then in office.

provided, however, that a Change in Control shall not be deemed to have occurred
if either (a) the closing price per share of the Common Stock for any five
Trading Days within the period of 10 consecutive Trading Days ending immediately
after the later of the Change in Control or the public announcement of the
Change in Control (in the case of a Change in Control under clause (1) above) or
ending immediately before the Change in Control (in the case of a Change in
Control under clauses (2) and (3) above) shall equal or exceed 105% of the
Conversion Price in effect on each such Trading Day, or (b)(i) at least 90% of
the consideration (excluding cash payments for fractional shares) in the
transaction or transactions constituting the Change in Control consists of
shares of common stock traded on a national securities exchange or quoted on the
Nasdaq National Market (or which will be so traded or quoted when issued or
exchanged in connection with such Change in Control) (such securities being
referred to as "Publicly Traded Securities") and as a result of such transaction
or transactions the Securities become convertible solely into such Publicly
Traded Securities and (ii) the consideration in the transaction or transactions
constituting the Change in Control consists of cash, Publicly Traded Securities
or a combination of cash and Publicly Traded Securities with an aggregate fair
market value (which,



                                       32
<PAGE>   38
in the case of Publicly Traded Securities, shall be equal to the average closing
price of such Publicly Traded Securities during the 10 consecutive Trading Days
commencing with the sixth trading day following consummation of the transaction
or transactions constituting the Change in Control) is at least 105% of the
conversion price in effect on the date immediately preceding the date of
consummation of such Change in Control.

        "Beneficial owner" shall be determined in accordance with Rule 13d-3
promulgated by the SEC under the Exchange Act, as in effect on the date of
execution of the Indenture, except that a person shall be deemed to be the
"beneficial owner" of all securities that such person has the right to acquire,
whether such right is exercisable immediately or only after the passage of time.

        "Voting Shares" means all outstanding shares of any class or classes
(however designated) of capital stock of the Company entitled to vote generally
in the election of the Board of Directors of the Company.

SECTION 3.11 CONDITIONS AND PROCEDURES RELATING TO THE COMPANY'S ELECTION TO PAY
             THE REPURCHASE PRICE IN COMMON STOCK.

        (a) The Company may elect to pay the Repurchase Price by delivery of
shares of Common Stock pursuant to Section 3.10 so long as the following
conditions precedent are satisfied:

            (i) The shares of Common Stock deliverable in payment of the
Repurchase Price shall have a fair market value as of the Repurchase Date of not
less than the Repurchase Price. For purposes of Section 3.10 and this Section
3.11, the fair market value of shares of Common Stock shall be determined by the
Company and shall be equal to 95% of the average of the Closing Prices of the
Common stock for the five consecutive Trading Days immediately preceding and
including the third Trading Day prior to the Repurchase Date:

            (ii) The shares of Common Stock to be issued upon repurchase of
Notes pursuant to Section 3.10 shall not require registration under any federal
securities law before such shares may be freely transferable without being
subject to any transfer restrictions under the Securities Act upon repurchase
pursuant to this Article 3 or, if such registration is required, such
registration shall be completed and shall become effective prior to the
Repurchase Date, and (B) shall not require registration with or approval of any
governmental authority under any state law or any other federal law before such
shares may be validly issued or delivered upon repurchase pursuant to this
Article 3, or if such registration is required or such approval must be
obtained, such registration shall be completed or such approval shall be
obtained prior to the Repurchase Date;

            (iii) The shares of Common Stock to be issued upon repurchase of
Notes pursuant to this Article 3 are, or shall have been, approved for listing
on the Nasdaq National Market or the New York Stock Exchange or listed on
another national securities exchange, in any case, prior to the Repurchase Date;
and




                                       33
<PAGE>   39
            (iv) All shares of Common Stock which may be issued upon repurchase
of Notes pursuant to this Article 3 will be issued out of the Company's
authorized but unissued Common Stock and, will upon issue, be duly and validly
issued and fully paid and non-assessable and free of any preemptive or similar
rights.

        If all of the conditions are set forth in this Section 3.11(a) are not
satisfied in accordance with the terms hereof, the Repurchase Price shall be
paid by the Company only in cash.

        (b) Any issuance of shares of Common Stock in respect of the Repurchase
Price shall be deemed to have been effected immediately prior to the close of
business on the Repurchase Date and the Person or Persons in whose name or names
any certificate or certificates for shares of Common Stock shall be issuable
upon such repurchase shall be deemed to have become on the Repurchase Date the
holder or holders of record of the shares represented thereby; provided,
however, that any surrender for repurchase on a date when the stock transfer
books of the Company shall be closed shall constitute the Person or Persons in
whose name or names the certificate or certificates for such shares are to be
issued as the record holder or holders thereof for all purposes at the opening
of business on the next succeeding day on which such stock transfer books are
open. No payment or adjustment shall be made for dividends or distributions on
any Common Stock issued upon repurchase of any Note pursuant to this Article 3
declared prior to the Repurchase Date.

        (c) No fractions of shares shall be issued upon repurchase of Notes
pursuant to this Article 3. If more than one Note shall be repurchased from the
same Holder and the Repurchase Price shall be payable in shares of Common Stock,
the number of full shares which shall be issuable upon such repurchase shall be
computed on the basis of the aggregate principal amount of the Notes so
repurchased. Instead of any fractional share of Common Stock which would
otherwise be issuable on the repurchase of any Note or Notes pursuant to this
Article 3, the Company will deliver to the applicable Holder its check for the
current market value of such fractional share. The current market value of a
fraction of a share is determined by multiplying the Closing Price of a full
share on the Trading Day immediately preceding the Repurchase Date by the
fraction, and rounding the result to the nearest cent.

        (d) Any issuance and delivery of certificates for shares of Common Stock
on repurchase of Notes pursuant to this Article 3 shall be made without charge
to the Holder of Notes being repurchased for such certificates or for any tax or
duty in respect of the issuance or delivery of such certificates or the Notes
represented thereby; provided, however, that the Company shall not be required
to pay any tax or duty which may be payable in respect of (i) income of the
Holder or (ii) any transfer involved in the issuance or delivery of certificates
for shares of Common Stock in a name other than that of the Holder of the Notes
being repurchased, and no such issuance or delivery shall be made unless and
until the Person requesting such issuance or delivery has paid to the Company
the amount of any such tax or duty or has established, to the satisfaction of
the Company, that such tax or duty has been paid.

SECTION 3.12 NOTICE; METHOD OF EXERCISING REPURCHASE RIGHT.

        Within 30 days after the occurrence of a Change in Control, the Company
shall mail a written notice (the "Company Notice") by first-class mail to the
Trustee and to each Holder (and





                                       34
<PAGE>   40
to beneficial owners as required by applicable law) and shall cause a copy of
such notice to be published in a daily newspaper of national circulation. The
notice shall include the form of a Repurchase Notice (as defined below) to be
completed by the Holder and shall state:

        (1) the date of such Change in Control and, briefly, the events causing
such Change in Control;

        (2) the date by which the Repurchase Notice pursuant to this Section
3.12 must be given;

        (3) the Repurchase Date;

        (4) the Repurchase Price;

        (5) whether the Repurchase Price will be paid in the form of cash or
Common Stock as provided in this Indenture and that such determination is
irrevocable;

        (6) briefly, the conversion rights of the Securities including, without
limitation, the current Conversion Price and any adjustments thereto;

        (7) the name and address of the Paying Agent and the Conversion Agent;

        (8) whether the lenders under the Company's Senior Indebtedness will
permit the payment of the Repurchase Price;

        (9) that Securities as to which a Repurchase Notice has been given may
be converted into Common Stock only to the extent that the Repurchase Notice has
been withdrawn in accordance with the terms of this Indenture;

        (10) the procedures that the Holder must follow to exercise rights under
Section 3.10;

        (11) the procedures for withdrawing a Repurchase Notice, including a
form of notice of withdrawal;

        (12) that the Holder must satisfy the requirements set forth in the
Securities in order to convert the Securities; and

        (13) the CUSIP number of the Securities as to which a Repurchase Notice
has been given.

        (b) A Holder may exercise its rights specified in Section 3.10 upon
delivery of a written notice of the exercise of such rights (a "Repurchase
Notice") to the Paying Agent at any time prior to the close of business on the
third Business Day prior to the Repurchase Date, stating:

        (1) the certificate number of each Security that the Holder will deliver
to be repurchased,



                                       35
<PAGE>   41

        (2) the portion of the principal amount of each Security that the Holder
will deliver to be repurchased, which portion must be $1,000 or an integral
multiple thereof; and

        (3) that such Security shall be repurchased pursuant to the terms and
conditions specified in this Indenture.

        The delivery of such Security to the Paying Agent prior to, on or after
the Repurchase Date (together with all necessary endorsements) at the office of
the Paying Agent shall be a condition to the receipt by the Holder of the
Repurchase Price therefor; provided, however, that such Repurchase Price shall
be so paid pursuant to Section 3.10 only if the Security so delivered to the
Paying Agent shall conform in all respects to the description thereof set forth
in the related Repurchase Notice.

        The Company shall repurchase from the Holder thereof, pursuant to
Section 3.10, a portion of a Security if the principal amount of such portion is
$1,000 or an integral multiple of $1,000. Provisions of this Indenture that
apply to the repurchase of all of a Security pursuant to Sections 3.10 through
3.17 also apply to the repurchase of such portion of such Security.

        Notwithstanding anything herein to the contrary, any Holder delivering
to the Paying Agent the Repurchase Notice contemplated by this Section 3.12(b)
shall have the right to withdraw such Repurchase Notice in whole or in a portion
thereof that is $1,000 or an integral multiple thereof at any time prior to the
close of business on the Business Day prior to the Repurchase Date by delivery
of a written notice of withdrawal to the Paying Agent in accordance with Section
3.13.

        The Paying Agent shall promptly notify the Company of the receipt by it
of any Repurchase Notice or written withdrawal thereof.

SECTION 3.13 EFFECT OF REPURCHASE NOTICE.

        Upon receipt by the Paying Agent of the Repurchase Notice specified in
Section 3.12(b), the Holder of the Security in respect of which such Repurchase
Notice was given shall (unless such Repurchase Notice is withdrawn as specified
below) thereafter be entitled to receive solely the Repurchase Price with
respect to such Security. Such Repurchase Price shall be paid to such Holder
promptly following the later of (i) the Repurchase Date with respect to such
Security (provided the conditions in Section 3.12(b) have been satisfied) and
(ii) the time of delivery of such Security to the Paying Agent by the Holder
thereof in the manner required by Section 3.12(b). Securities in respect of
which a Repurchase Notice has been given by the Holder thereof may not be
converted into shares of Common Stock on or after the date of the delivery of
such Repurchase Notice unless such Repurchase Notice has first been validly
withdrawn.

        A Repurchase Notice may be withdrawn by means of a written notice of
withdrawal delivered by the Holder to the office of the Paying Agent at any time
prior to the close of business on the Business Day prior to the Repurchase Date
to which it relates, specifying:

        (1) the certificate number of each Security in respect of which such
notice of withdrawal is being submitted;



                                       36
<PAGE>   42

        (2) the principal amount of the Security or portion thereof with respect
to which such notice of withdrawal is being submitted; and

        (3) the principal amount, if any, of such Security that remains subject
to the original Repurchase Notice and that has been or will be delivered for
repurchase by the Company.

SECTION 3.14 DEPOSIT OF REPURCHASE PRICE.

        On or before the Repurchase Date, the Company shall deposit with the
Trustee or with the Paying Agent (or, if the Company is acting as the Paying
Agent, shall segregate and hold in trust as provided in Section 2.4) an amount
of money or a number of shares of Common Stock, as provided herein, sufficient
to pay the aggregate Repurchase Price of all the Securities or portions thereof
that are to be repurchased as of such Repurchase Date. The manner in which the
deposit required by this Section 3.14 is made by the Company shall be at the
option of the Company, provided that such deposit shall be made in a manner such
that the Trustee or the Paying Agent shall have immediately available funds on
the Repurchase Date; provided further, that if such payment is made on the
Repurchase Date it must be received by the Trustee or Paying Agent, as the case
may be, by 10:00 a.m., New York City time, on such date.

        If the Paying Agent holds, in accordance with the terms hereof, money or
shares of Common Stock, as provided herein, sufficient to pay the Repurchase
Price of any Security tendered for repurchase on the Business Day prior to the
Repurchase Date, then, on and after the Repurchase Date, such Security will
cease to be outstanding and interest on such Security will cease to accrue and
will be deemed paid, whether or not such Security is delivered to the Paying
Agent, and all other rights of the Holder in respect thereof shall terminate
(other than the right to receive the Repurchase Price upon delivery of such
Security).

SECTION 3.15 SECURITIES REPURCHASED IN PART.

        Any Security that is to be repurchased only in part shall be surrendered
at the office of the Paying Agent (with, if the Company or the Trustee so
requires, due endorsement by, or a written instrument of transfer in form
satisfactory to the Company and the Trustee duly executed by, the Holder thereof
or such Holder's attorney duly authorized in writing), and the Company shall
execute and the Trustee shall authenticate and deliver to the Holder of such
Security, without service charge, a new Security or Securities, or such
authorized denomination or denominations as may be requested by such Holder, in
aggregate principal amount equal to, and in exchange for, the portion of the
principal amount of the Security so surrendered that is not repurchased.

SECTION 3.16 COMPLIANCE WITH SECURITIES LAWS UPON REPURCHASE OF SECURITIES.

        In connection with any offer to repurchase or repurchase of Securities
under Section 3.10 hereof (provided that such offer or repurchase constitutes an
"issuer tender offer" for purposes of Rule 13e-4 (which term, as used herein,
includes any successor provision thereto) at the time of such offer or
repurchase), the Company shall (i) comply with Rule 13e-4 and Rule 14e-1 under
the Exchange Act, (ii) file the related Schedule 13E-4 (or any successor
schedule, form or report) under the Exchange Act, and (iii) otherwise comply
with all federal and state securities laws so



                                       37
<PAGE>   43

as to permit the rights of the Holders and obligations of the Company under
Sections 3.10 through 3.17 to be exercised in the time and in the manner
specified therein.

SECTION 3.17 REPAYMENT TO THE COMPANY.

        Subject to the provisions of Section 5.7, to the extent that the
aggregate amount of cash or the number of shares of Common Stock, as provided
herein, deposited by the Company pursuant to Section 3.14 exceeds the aggregate
Repurchase Price of the Securities or portions thereof to be repurchased, then,
promptly after the Business Day following the Repurchase Date, the Trustee or
the Paying Agent, as the case may be, shall return any such excess to the
Company.

                                   ARTICLE 4.

                                   CONVERSION

SECTION 4.1 CONVERSION PRIVILEGE.

        At any time after 90 days following the latest date of original issuance
of the Securities and prior to the close of business on February 1, 2007, a
Holder of a Security may convert such Security into Common Stock, at the
conversion price then in effect, together with those rights specified in Section
4.15 hereof; provided that, if such Security is called for redemption pursuant
to Article 3, such conversion right shall terminate at the close of business on
the third business day before the redemption date for such Security (unless the
Company shall default in making the redemption payment then due, in which case
the conversion right shall terminate on the date such default is cured and such
Security is redeemed). The number of shares of Common Stock issuable upon
conversion of a Security shall be determined by dividing the principal amount of
the Security or portion thereof surrendered for conversion by the conversion
price in effect on the conversion date. The initial conversion price is set
forth in paragraph 9 of the Securities and is subject to adjustment as provided
in this Article 4.

        A Holder may convert a portion of a Security equal to $1,000 or any
integral multiple thereof. Provisions of this Indenture that apply to conversion
of all of a Security also apply to conversion of a portion of a Security.

        A Security in respect of which a Holder has delivered a Repurchase
Notice pursuant to Section 3.12(b) exercising the option of such Holder to
require the Company to repurchase such Security may be converted only if such
Repurchase Notice is withdrawn by a written notice of withdrawal delivered to
the Paying Agent prior to the close of business on the Repurchase Date in
accordance with Section 3.13.

        A Holder of Securities is not entitled to any rights of a holder of
Common Stock until such Holder has converted his Securities into Common Stock
and, upon such conversion, only to the extent such Securities are deemed to have
been converted into Common Stock pursuant to this Article 4.



                                       38
<PAGE>   44

SECTION 4.2 CONVERSION PROCEDURE.

        To convert a Security, a Holder must (i) complete and manually sign the
conversion notice on the back of the Security and deliver such notice to the
Conversion Agent, (ii) surrender the Security to the Conversion Agent, (iii)
furnish appropriate endorsements and transfer documents if required by the
Registrar or the Conversion Agent and (iv) pay any transfer or other tax, if
required by Section 4.4. The date on which the Holder satisfies all of the
foregoing requirements is the conversion date. As soon as practicable after the
conversion date, the Company shall deliver to the Holder through the Conversion
Agent a certificate for the number of whole shares of Common Stock issuable upon
the conversion and cash in lieu of any fractional shares pursuant to Section
4.3.

        The person in whose name the certificate is registered shall be deemed
to be a stockholder of record on the conversion date; provided, however, that no
surrender of a Security on any date when the stock transfer books of the Company
shall be closed shall be effective to constitute the person or persons entitled
to receive the shares of Common Stock upon such conversion as the record holder
or holders of such shares of Common Stock on such date, but such surrender shall
be effective to constitute the person or persons entitled to receive such shares
of Common Stock as the record holder or holders thereof for all purposes at the
close of business on the next succeeding day on which such stock transfer books
are open; provided, further, that such conversion shall be at the Conversion
Price in effect on the date that such Security shall have been surrendered for
conversion, as if the stock transfer books of the Company had not been closed.
Upon conversion of a Security, such person shall no longer be a Holder of such
Security.

        No payment or adjustment will be made for accrued interest on a
converted Security or for dividends or distributions on shares of Common Stock
issued upon conversion of a Security, but if any Holder surrenders a Security
for conversion between the record date for the payment of an installment of
interest and the next interest payment date, then, notwithstanding such
conversion, the interest payable on such interest payment date shall be paid to
the Holder of such Security on such record date. In such event, such Security,
when surrendered for conversion, must be accompanied by delivery of a check or
draft payable to the Conversion Agent in an amount equal to the interest payable
on such interest payment date on the portion so converted. If such payment does
not accompany such Security, the Security shall not be converted; provided,
however, that no such check or draft shall be required if such Security has been
called for redemption between such record date and the date three business days
after such interest payment date, or if such Security is surrendered for
conversion on the interest payment date. If the Company defaults in the payment
of interest payable on the interest payment date, the Conversion Agent shall
repay such funds to the Holder.

        If a Holder converts more than one Security at the same time, the number
of shares of Common Stock issuable upon the conversion shall be based on the
aggregate principal amount of Securities converted.

        Upon surrender of a Security that is converted in part, the Company
shall execute, and the Trustee shall authenticate and deliver to the Holder, a
new Security equal in principal amount to the unconverted portion of the
Security surrendered.



                                       39
<PAGE>   45

SECTION 4.3 ADJUSTMENTS BELOW PAR VALUE.

        Before taking any action which would cause an adjustment decreasing the
Conversion Price so that the shares of Common Stock issuable upon conversion of
the Securities would be issued for less than the par value of such Common Stock,
the Company will take all corporate action which may be necessary in order that
the Company may validly and legally issue fully paid and nonassessable shares of
such Common Stock at such adjusted Conversion Price.

SECTION 4.4 TAXES ON CONVERSION.

        If a Holder converts a Security, the Company shall pay any documentary,
stamp or similar issue or transfer tax due on the issue of shares of Common
Stock upon such conversion. However, the Holder shall pay any such tax which is
due because the Holder requests the shares to be issued in a name other than the
Holder's name. The Conversion Agent may refuse to deliver the certificates
representing the Common Stock being issued in a name other than the Holder's
name until the Conversion Agent receives a sum sufficient to pay any tax which
will be due because the shares are to be issued in a name other than the
Holder's name. Nothing herein shall preclude any tax withholding required by law
or regulations.

SECTION 4.5 COMPANY TO PROVIDE STOCK.

        The Company shall, prior to issuance of any Securities hereunder, and
from time to time as may be necessary, reserve, out of its authorized but
unissued Common Stock a sufficient number of shares of Common Stock to permit
the conversion of all outstanding Securities for shares of Common Stock. The
shares of Common Stock or other securities issued upon conversion of the
Securities shall bear any legend required in accordance with Section 2.6(g)
hereof.

        No fractional shares of Common Stock or scrip representing fractional
shares shall be issued upon conversion of Securities. If more than one Security
shall be surrendered for conversion at one time by the same holder, the number
of full shares which shall be issuable upon conversion shall be computed on the
basis of the aggregate principal amount of the Securities (or specified portions
thereof to the extent permitted hereby) so surrendered. If any fractional share
of stock would be issuable upon the conversion of any Security or Securities,
the Company shall make an adjustment thereof in cash at the current market value
thereof. For these purposes, the current market value of a share of Common Stock
shall be the Closing Price on the first day (which is not a Legal Holiday)
immediately preceding the day on which the Securities (or specified portions
thereof) are deemed to have been converted.

        The Company covenants that all shares of Common Stock delivered upon
conversion of the Securities shall be newly issued shares or treasury shares,
shall be duly authorized, validly issued, fully paid and non-assessable and
shall be free from preemptive rights and free of any lien or adverse claim.

        The Company will endeavor promptly to comply with all federal and state
securities laws regulating the offer and delivery of shares of Common Stock upon
conversion of Securities, if any, and will list or cause to have quoted such
shares of Common Stock on each national securities exchange or in the
over-the-counter market or such other market on which the Common Stock is then
listed or quoted.




                                       40
<PAGE>   46
SECTION 4.6 ADJUSTMENT OF CONVERSION PRICE.

        The conversion price (the "Conversion Price") shall be that price set
forth in paragraph 9 of the form of Security attached hereto as Exhibit A and
shall be adjusted from time to time by the Company as follows:

        (a) In case the Company shall (i) pay a dividend or other distribution
in shares of Common Stock to holders of Common Stock, (ii) subdivide its
outstanding Common Stock into a greater number of shares, (iii) combine its
outstanding Common Stock into a smaller number of shares, or (iv) reclassify its
outstanding Common Stock, the Conversion Price in effect immediately prior
thereto shall be adjusted so that the Holder of any Security thereafter
surrendered for conversion shall be entitled to receive the number of shares of
Common Stock which it would have owned or have been entitled to receive had such
Security been converted immediately prior to the happening of such event. An
adjustment made pursuant to this subsection (a) shall become effective
immediately after the record date in the case of a dividend or distribution and
shall become effective immediately after the effective date in the case of
subdivision or combination.

        (b) In case the Company shall issue rights, warrants or options to all
or substantially all holders of its Common Stock entitling them (for a period
commencing no earlier than the record date described below and expiring not more
than 45 days after such record date) to subscribe for or purchase shares of
Common Stock (or securities convertible into Common Stock) at a price per share
less than the current market price per share of Common Stock (as determined in
accordance with subsection (e) below) at the record date for the determination
of stockholders entitled to receive such rights, warrants or options, the
Conversion Price in effect immediately prior thereto shall be adjusted so that
the Conversion Price shall equal the price determined by multiplying the
Conversion Price in effect immediately prior to such record date by a fraction
of which the numerator shall be the number of shares of Common Stock outstanding
on such record date, plus the number of shares which the aggregate subscription
or purchase price for the total number of shares of Common Stock offered by the
rights, warrants or options so issued (or the aggregate conversion price of the
convertible securities offered by such rights, warrants or options) would
purchase at such current market price, and of which the denominator shall be the
number of shares of Common Stock outstanding on such record date plus the number
of additional shares of Common Stock offered by such rights, warrants or options
(or into which the convertible securities so offered by such rights, warrants or
options are convertible). Such adjustment shall be made successively whenever
any such rights, warrants or options are issued, and shall become effective
immediately after such record date. If at the end of the period during which
such rights, warrants or options are exercisable not all rights, warrants or
options shall have been exercised, the adjusted Conversion Price shall be
immediately readjusted to what it would have been upon application of the
foregoing adjustment substituting the number of additional shares of Common
Stock actually issued (or the number of shares of Common Stock issuable upon
conversion of convertible securities actually issued) for the total number of
shares of Common Stock offered (or the convertible securities offered).

        (c) In case the Company shall distribute to all or substantially all
holders of its Common Stock any shares of capital stock of the Company (other
than Common Stock) or evidences of its indebtedness, cash, other securities or
other assets, or shall distribute to all or

                                       41
<PAGE>   47
substantially all holders of its Common Stock rights, warrants or options to
subscribe for or purchase any of its securities (excluding (i) those rights and
warrants referred to in subsection (b) above; (ii) those dividends,
distributions, subdivisions and combinations referred to in subsection(a) above;
and (iii) dividends and distributions paid in cash from retained earnings in an
aggregate amount that, combined together with (A) all other such cash
distributions made within the preceding 12 months in respect of which no
adjustment has been made under this Section 4.6 and (B) the fair market value of
consideration payable in respect of any repurchases (including by way of tender
offers) by the Company or any of its Subsidiaries or Affiliates, or any employee
benefit plan for the benefit of employees of the Company or any of its
Subsidiaries or Affiliates (a "Company Benefit Plan"), of Common Stock concluded
within the preceding 12 months, in each case in respect of which no adjustment
has been made under this Section 4.6, does not exceed 12.5% of Market
Capitalization as of the record date for such distribution), then in each such
case the Conversion Price shall be adjusted so that the same shall equal the
price determined by multiplying the Conversion Price in effect immediately prior
to the date of such distribution or purchase by a fraction of which the
numerator shall be the current market price per share (as defined in subsection
(e) below) of the Common Stock on the record date mentioned below less the fair
market value on such record date (as determined by the Board of Directors of the
Company, whose determination shall be conclusive evidence of such fair market
value) of the portion of the capital stock or evidences of indebtedness,
securities or assets so distributed or of such rights, warrants or options, in
each case as applicable to one share of Common Stock, and of which the
denominator shall be the current market price per share (as defined in
subsection (e) below) of the Common Stock on such record date. Such adjustment
shall become effective immediately after the record date for the determination
of stockholders entitled to receive such distribution. Notwithstanding the
foregoing, in the event that the Company shall distribute (AA) rights, warrants
or options (other than those referred to in subsection (b) above) ("Rights") pro
rata to holders of Common Stock, the Company may, in lieu of making any
adjustment pursuant to this Section 4.6, or (BB) rights issued pursuant to the
Company's Rights Agreement, dated September 25, 1998, pro rata to holders of
Common Stock the Company shall, make proper provision so that each holder of a
Security who converts such Security (or any portion thereof) after the record
date for such distribution and prior to the expiration or redemption of the
Rights shall be entitled to receive upon such conversion, in addition to the
Conversion Shares, a number of Rights to be determined as follows: (x) if such
conversion occurs on or prior to the date for the distribution to the holders of
Rights of separate certificates evidencing such Rights (the "Distribution
Date"), the same number of Rights to which a holder of a number of shares of
Common Stock equal to the number of Conversion Shares is entitled at the time of
such conversion in accordance with the terms and provisions of and applicable to
the Rights; and (y) if such conversion occurs after the Distribution Date, the
same number of Rights to which a holder of the number of shares of Common Stock
into which the principal amount of the Security so converted was convertible
immediately prior to the Distribution Date would have been entitled on the
Distribution Date in accordance with the terms and provisions of, and applicable
to, the Rights. If the Company implements a new stockholder rights plan, the
Company agrees that such rights plan will provide that upon conversion of the
Notes, the Holders of the Common Stock issued upon


                                       42
<PAGE>   48

conversion shall receive the rights issued under such plan, whether or not
such rights have separated from the Common Stock at the time of such conversion.
If the rights under such new plan have become separated from the Common Stock
prior to the conversion of a Security, the Holders of the Common Stock issued
upon conversion shall receive the Rights that they would have received if the
Security had been converted immediately prior to the separation of the Rights.

        (d) In case the Company or any of its Subsidiaries or any Company
Benefit Plan shall repurchase (including by way of tender offer) shares of
Common Stock, and the fair market value of the sum of (i) the aggregate
consideration paid for such Common Stock, (ii) the aggregate fair market value
of cash dividends and distributions of the type described in clause (iii) of the
preceding paragraph (c) paid within the twelve (12) months preceding the date of
purchase of such shares of Common Stock in respect of which no adjustment
pursuant to this Section 4.6 previously has been made, and (iii) the aggregate
fair market value of any amounts previously paid for the repurchase of Common
Stock of a type described in this paragraph (d) within the twelve (12) months
preceding the date of purchase of such shares of Common Stock in respect of
which no adjustment pursuant to this Section 4.6 previously has been made,
exceeds 12.5% of Market Capitalization on the date of, and after giving effect
to, such repurchase, then the Conversion Price shall be adjusted so that the
same shall equal the price determined by multiplying the Conversion Price in
effect immediately prior to the date of such distribution or purchase by a
fraction of which the numerator shall be the current market price per share (as
defined in subsection (e) below) of the Common Stock on the date of such
repurchase, less the amount of cash so distributed (through dividend,
distribution or repurchase of shares) applicable to one share of Common Stock
and of which the denominator shall be the current market price per share (as
defined in subsection (e) below) of the Common Stock on the date of such
repurchase. Such adjustment shall become effective immediately after the date of
such repurchase.

        (e) For the purpose of any computation under subsections (b), (c) and
(d) above, the current market price per share of Common Stock on any date shall
be deemed to be the average of the Closing Prices for 20 consecutive Trading
Days commencing 30 Trading Days before the record date with respect to any
distribution, issuance or other event requiring such computation. The Closing
Price for each day shall be (i) the last sale price, or the closing bid price if
no sale occurred, of such class of stock on the principal securities exchange on
which such class of stock is listed, if the Common Stock is listed or admitted
for trading on any national securities exchange, (ii) the last reported sale
price of Common Stock on The Nasdaq Stock Market, or any similar system of
automated dissemination of quotations of securities prices then in common use,
if so quoted, or (iii) if not quoted as described in clause (i), the mean
between the high bid and low asked quotations for Common Stock as reported by
the National Quotation Bureau Incorporated if at least two securities dealers
have inserted both bid and asked quotations for such class of stock on at least
5 of the 10 preceding days. If the Common Stock is quoted on a national
securities or central market system, in lieu of a market or quotation system
described above, the Closing Price shall be determined in the manner set forth
in clause (iii) of the preceding sentence if bid and asked quotations are
reported but actual transactions are not, and in the manner set forth in clause
(ii) of the preceding sentence if actual transactions are reported. If none of
the conditions set forth above is met, the Closing Price of Common Stock on any
day or the average of such last reported sale prices for any period shall be the
fair market value of such class of stock as determined by a member firm of the
New York Stock Exchange, Inc. selected by the Company. As used herein the term
"Trading Days" with respect to Common Stock means (i) if the Common Stock is
listed or admitted for trading on any national securities exchange,

                                       43
<PAGE>   49
days on which such national securities exchange is open for business or (ii) if
the Common Stock is quoted on The Nasdaq Stock Market or any similar system of
automated dissemination of quotations of securities prices, days on which trades
may be made on such system.

        (f) Rights, warrants or options distributed by the Company to all
holders of Common Stock entitling the holders thereof to subscribe for or
purchase shares of the Company's capital stock (either initially or under
certain circumstances), which rights, warrants or options, until the occurrence
of a specified event or events ("Trigger Event"):

        (1) are deemed to be transferred with such shares of Common Stock,

        (2) are not exercisable, and

        (3) are also issued in respect of future issuances of Common Stock,

shall not be deemed distributed for purposes of this Section 4.6 until the
occurrence of the earliest Trigger Event. In addition, in the event of any
distribution of rights, warrants or options, or any Trigger Event with respect
thereto, that shall have resulted in an adjustment to the Conversion Price under
this Section 4.6, (1) in the case of any such rights, warrants or options which
shall all have been redeemed or repurchased without exercise by any holders
thereof, the Conversion Price shall be readjusted upon such final redemption or
repurchase to give effect to such distribution or Trigger Event, as the case may
be, as though it were a cash distribution, equal to the per share redemption or
repurchase price received by a holder of Common Stock with respect to such
rights, warrants or options (assuming such holder had retained such rights,
warrants or options), made to all holders of Common Stock as of the date of such
redemption or repurchase, and (2) in the case of any such rights, warrants or
options all of which shall have expired without exercise by any holder thereof,
the Conversion Price shall be readjusted as if such issuance had not occurred.

        (g) In any case in which this Section 4.6 shall require that an
adjustment be made immediately following a record date established for purposes
of Section 4.6, the Company may elect to defer (but only until five Business
Days following the filing by the Company with the Trustee of the certificate
described in Section 4.10 below) issuing to the holder of any Security converted
after such record date the shares of Common Stock and other capital stock of the
Company issuable upon such conversion over and above the shares of Common Stock
and other capital stock of the Company issuable upon such conversion only on the
basis of the Conversion Price prior to adjustment; and, in lieu of the shares
the issuance of which is so deferred, the Company shall issue or cause its
transfer agents to issue due bills or other appropriate evidence of the right to
receive such shares.

SECTION 4.7 NO ADJUSTMENT.

        No adjustment in the Conversion Price shall be required unless the
adjustment would require an increase or decrease of at least 1% in the
Conversion Price as last adjusted; provided, however, that any adjustments which
by reason of this Section 4.7 are not required to be made shall be carried
forward and taken into account in any subsequent adjustment. All calculations


                                       44
<PAGE>   50
under this Article 4 shall be made to the nearest cent or to the nearest
one-hundredth of a share, as the case may be.

        No adjustment need be made for rights to purchase Common Stock or
issuances of Common Stock pursuant to a Company plan for reinvestment of
dividends or interest.

        No adjustment need be made for a change in the par value or a change to
no par value of the Common Stock.

        To the extent that the Securities become convertible into cash, no
adjustment need be made thereafter as to the cash. Interest will not accrue on
the cash.

SECTION 4.8 EQUIVALENT ADJUSTMENTS.

        In the event that, as a result of an adjustment made pursuant to Section
4.6 above, the holder of any Security thereafter surrendered for conversion
shall become entitled to receive any shares of capital stock of the Company
other than shares of its Common Stock, thereafter the Conversion Price of such
other shares so receivable upon conversion of any Securities shall be subject to
adjustment from time to time in a manner and on terms as nearly equivalent as
practicable to the provisions with respect to Common Stock contained in this
Article 4.

SECTION 4.9 ADJUSTMENT FOR TAX PURPOSES.

        The Company shall be entitled to make such reductions in the Conversion
Price, in addition to those required by Section 4.6, as it in its discretion
shall determine to be advisable in order that any stock dividends, subdivision
of shares, distribution of rights to purchase stock or securities, or a
distribution or securities convertible into or exchangeable for stock hereafter
made by the Company to its stockholders shall not be taxable.

SECTION 4.10 NOTICE OF ADJUSTMENT.

        Whenever the Conversion Price is adjusted, or Securityholders become
entitled to other Securities or due bills, the Company shall promptly mail to
Securityholders a notice of the adjustment and file with the Trustee an
Officers' Certificate briefly stating the facts requiring the adjustment and the
manner of computing it. The certificate shall be conclusive evidence of the
correctness of such adjustment and the Trustee may conclusively assume that,
unless and until such certificate is received by it, no such adjustment is
required.

SECTION 4.11 NOTICE OF CERTAIN TRANSACTIONS.

        In case:

        (a) the Company shall declare a dividend (or any other distribution) on
its Common Stock (other than in cash out of retained earnings); or

        (b) the Company shall authorize the granting to the holders of its
Common Stock of rights, warrants or options to subscribe for or purchase any
share of any class or any other rights, warrants or options; or


                                       45
<PAGE>   51

        (c) of any reclassification of the Common Stock of the Company (other
than a subdivision or combination of its outstanding Common Stock, or a change
in par value, or from par value to no par value, or from no par value to par
value), or of any consolidation or merger to which the Company is a party and
for which approval of any stockholders of the Company is required, or of the
sale or transfer of all or substantially all of the assets of the Company; or

        (d) of the voluntary or involuntary dissolution, liquidation or
winding-up of the Company;

the Company shall cause to be filed with the Trustee and to be mailed to each
holder of Securities at its address appearing on the list, provided for in
Section 2.5 of this Indenture, as promptly as possible but in any event at least
fifteen days prior to the applicable date hereinafter specified, a notice
stating (x) the date on which a record is to be taken for the purpose of such
dividend, distribution or rights, warrants or options, or, if a record is not to
be taken, the date as of which the holders of Common Stock of record to be
entitled to such dividend, distribution or rights are to be determined, or (y)
the date on which such reclassification, consolidation, merger, sale, transfer,
dissolution, liquidation or winding-up is expected to become effective or occur,
and the date as of which it is expected that holders of Common Stock of record
shall be entitled to exchange their Common Stock for securities or other
property deliverable upon such reclassification, consolidation, merger, sale,
transfer, dissolution, liquidation or winding-up. Failure to give such notice,
or any defect therein, shall not affect the legality or validity of such
dividend, distribution, reclassification, consolidation, merger, sale, transfer,
dissolution, liquidation or winding-up.

SECTION 4.12 EFFECT OF RECLASSIFICATION, CONSOLIDATION, MERGER OR SALE ON
             CONVERSION PRIVILEGE.

        If any of the following shall occur, namely: (i) any reclassification or
change of outstanding shares of Common Stock (other than a change in par value,
or from par value to no par value, or from no par value to par value, or as a
result of a subdivision or combination); (ii) any consolidation, combination or
merger to which the Company is a party other than a merger in which the Company
is the continuing corporation and which does not result in any reclassification
of, or change (other than a change in name, or par value, or from par value to
no par value, or from no par value to par value, or as a result of a subdivision
or combination) in, outstanding shares of Common Stock; or (iii) any sale or
conveyance of all or substantially all of the property or business of the
Company, then the Company, or such successor or purchasing corporation, as the
case may be, shall, as a condition precedent to such reclassification, change,
consolidation, merger, sale or conveyance, execute and deliver to the Trustee a
supplemental indenture providing that the Holder of each Security then
outstanding shall have the right to convert such Security into the kind and
amount of shares of stock and other securities and property (including cash)
receivable upon such reclassification, change, consolidation, merger, sale or
conveyance by a holder of the number of shares of Common Stock deliverable upon
conversion of such Security immediately prior to such reclassification, change,
consolidation, merger, sale or conveyance. Such supplemental indenture shall
provide for adjustments of the Conversion Price which shall be as nearly
equivalent as may be practicable to the adjustments of the Conversion Price
provided for in this Article 4. The foregoing, however, shall not in any way
affect the right a holder of a  Security may otherwise have, pursuant to clause
(ii) of the last

                                       46
<PAGE>   52
sentence of subsection (c) of Section 4.6, to receive Rights upon conversion of
a Security. If, in the case of any such consolidation, merger, sale or
conveyance, the stock or other securities and property (including cash)
receivable thereupon by a holder of Common Stock includes shares of stock or
other securities and property of a corporation other than the successor or
purchasing corporation, as the case may be, in such consolidation, merger, sale
or conveyance, then such supplemental indenture shall also be executed by such
other corporation and shall contain such additional provisions to protect the
interests of the Holders of the Securities as the Board of Directors of the
Company shall reasonably consider necessary by reason of the foregoing. The
provision of this Section 4.12 shall similarly apply to successive
consolidations, mergers, sales or conveyances. Notwithstanding the foregoing, a
distribution by the Company to all or substantially all holders of its Common
Stock for which an adjustment to the Conversion Price or provision for
conversion of the Securities may be made pursuant to Section 4.6 hereof shall
not be deemed to be a sale or conveyance of all or substantially all of the
property or business of the Company for purposes of this Section 4.12.

        In the event the Company shall execute a supplemental indenture pursuant
to this Section 4.12, the Company shall promptly file with the Trustee an
Officers' Certificate briefly stating the reasons therefor, the kind or amount
of shares of stock or securities or property (including cash) receivable by
Holders of the Securities upon the conversion of their Securities after any such
reclassification, change, consolidation, merger, sale or conveyance, any
adjustment to be made with respect thereto and that all conditions precedent
have been complied with.

SECTION 4.13 TRUSTEE'S DISCLAIMER.

        The Trustee has no duty to determine when an adjustment under this
Article 4 should be made, how it should be made or what such adjustment should
be made, but may accept as conclusive evidence of the correctness of any such
adjustment, and shall be protected in relying upon, the Officers' Certificate
with respect thereto which the Company is obligated to file with the Trustee
pursuant to Section 4.10. The Trustee makes no representation as to the validity
or value of any securities or assets issued upon conversion of Securities, and
the Trustee shall not be responsible for the Company's failure to comply with
any provisions of this Article 4.

        The Trustee shall not be under any responsibility to determine the
correctness of any provisions contained in any supplemental indenture executed
pursuant to Section 4.12, but may accept as conclusive evidence of the
correctness thereof, and shall be protected in relying upon, the Officers'
Certificate with respect thereto which the Company is obligated to file with the
Trustee pursuant to Section 4.12.

SECTION 4.14 VOLUNTARY REDUCTION.

        The Company from time to time may reduce the Conversion Price by any
amount for any period of time if the period is at least 20 days or such longer
period as may be required by law and if the reduction is irrevocable during the
period; provided, that in no event may the Conversion Price be less than the par
value of a share of Common Stock.




                                       47
<PAGE>   53
                                   ARTICLE 5.

                                  SUBORDINATION

SECTION 5.1 SECURITIES SUBORDINATED TO SENIOR INDEBTEDNESS.


        The Company covenants and agrees, and each holder of Securities by his
acceptance thereof likewise covenants and agrees, that all Securities are
subject to the provisions of this Article 5; and each Person holding any
Security, whether upon original issue or upon transfer or assignment thereof,
accepts and agrees to be bound by such provisions and acknowledges that such
provisions are for the benefit of, and shall be enforceable directly by, the
holders of Senior Indebtedness.

        Each holder of Securities authorizes and directs the Trustee on such
holder's behalf to take such action as may be necessary or appropriate, in the
sole discretion of the Trustee, to acknowledge or effectuate the subordination
between the holders of Securities and the holders of Senior Indebtedness as
provided in this Article and appoints the Trustee as such holder's
attorney-in-fact for any and all such purposes.

        The payment of the principal of, premium, if any (including the
Make-Whole Payment, if any), and interest on and any other payment due pursuant
to this Indenture or any Securities issued hereunder (including, without
limitation, the payment or deposit of the redemption price or repurchase price
pursuant to Article 3 and any deposit pursuant to Section 6.3) shall, to the
extent and in the manner hereinafter set forth, be subordinated and subject in
right of payment to the prior payment in full of all Senior Indebtedness,
whether outstanding at the date of this Indenture or thereafter created,
incurred, assumed or guaranteed.

SECTION 5.2 SECURITIES SUBORDINATED TO PRIOR PAYMENT OF ALL SENIOR INDEBTEDNESS
            ON DISSOLUTION, LIQUIDATION, REORGANIZATION, ETC., OF THE COMPANY.

        Upon any payment or distribution of the assets of the Company of any
kind or character, whether in cash, property or securities (including any
collateral at any time securing the Securities), to creditors upon any
dissolution, winding-up, total or partial liquidation, or reorganization of the
Company (whether voluntary or involuntary, or in bankruptcy, insolvency,
reorganization, liquidation, or receivership proceedings, or upon an assignment
for the benefit of creditors, or any marshalling of the assets and liabilities
of the Company, or otherwise), then in such event:

        (a) all Senior Indebtedness (including principal thereof and interest
thereon) shall first be paid in full before any Payment of the Securities (as
defined in Section 5.5) is made;

        (b) any payment or distribution of assets of the Company of any kind or
character, whether in cash, property or securities (including any collateral at
any time securing the Securities) (other than Reorganization Securities), to
which the Holders or the Trustee on behalf of the Holders would be entitled
except for the provisions of this Article 5, including any such payment or
distribution which may be payable or deliverable by reason of the payment of
another debt of the Company being subordinated to the payment of the Securities,
shall be paid


                                       48
<PAGE>   54
or delivered by any debtor, Custodian or other person making such payment or
distribution, directly to the holders of the Senior Indebtedness or their
representative or representatives, or to the trustee or trustees under any
indenture pursuant to which any instruments evidencing any of such Senior
Indebtedness may have been issued, ratably according to the aggregate amounts
remaining unpaid on account of the principal of and interest on the Senior
Indebtedness held or represented by each, for application to payment of all
Senior Indebtedness remaining unpaid, to the extent necessary to pay all Senior
Indebtedness in full after giving effect to any concurrent payment or
distribution, or provision therefor, to the holders of such Senior Indebtedness;
and

        (c) in the event that, notwithstanding the foregoing provisions of this
Section 5.2, any payment or distribution of assets of the Company of any kind or
character, whether in cash, property or securities (other than Reorganization
Securities), shall be received by the Trustee or the Holders before all Senior
Indebtedness is paid in full, such payment or distribution (subject to the
provisions of Sections 5.6 and 5.7) shall be held in trust for the benefit of,
and shall be immediately paid or delivered by the Trustee or such Holders, as
the case may be, to the holders of Senior Indebtedness remaining unpaid, or
their Representative or Representatives, ratably according to the aggregate
amounts remaining unpaid on account of the principal of and interest on the
Senior Indebtedness held or represented by each, for application to the payment
of all Senior Indebtedness remaining unpaid, to the extent necessary to pay all
Senior Indebtedness in full after giving effect to any concurrent payment or
distribution, or provision therefor, to or for the holders of such Senior
Indebtedness.

        The Company shall give prompt notice to the Trustee of any dissolution,
winding-up, liquidation or reorganization of the Company.

        Upon any distribution of assets of the Company referred to in this
Article 5, the Trustee, subject to the provisions of Sections 9.1 and 9.2, and
the Holders shall be entitled to rely upon any order or decree by any court of
competent jurisdiction in which such dissolution, winding-up, liquidation or
reorganization proceeding is pending, or a certificate of the liquidating
trustee or agent or other person making any distribution to the Trustee or to
the Holders, for the purpose of ascertaining the persons entitled to participate
in such distribution, the holders of the Senior Indebtedness and other
indebtedness of the Company, the amount thereof or payable thereon, the amount
or amounts paid or distributed thereon and all other facts pertinent thereto or
to this Article 5; provided that the foregoing shall apply only if such court,
trustee, liquidating trustee or other person has been fully apprised of the
provisions of this Article.

SECTION 5.3 SECURITYHOLDERS TO BE SUBROGATED TO RIGHT OF HOLDERS OF SENIOR
            INDEBTEDNESS.

        Subject to the prior payment in full of all Senior Indebtedness, the
Holders shall be subrogated (equally and ratably with the holders of all
indebtedness of the Company which by its express terms is subordinated to
indebtedness of the Company to substantially the same extent as the Securities
are subordinated and is entitled to like rights of subrogation) to the rights of
the holders of Senior Indebtedness to receive payments or distributions of
assets of the Company applicable to the Senior Indebtedness until the principal
of and interest on the Securities shall be paid in full, and for purposes of
such subrogation, no payments or distributions to the holders of Senior
Indebtedness of assets, whether in cash, property or securities, distributable
to the holders


                                       49
<PAGE>   55
of Senior Indebtedness under the provisions hereof to which the Holders would be
entitled except for the provisions of this Article 5, and no payment pursuant to
the provisions of this Article 5 to the holders of Senior Indebtedness by the
Holders shall, as among the Company, its creditors other than the holders of
Senior Indebtedness, and the Holders, be deemed to be a payment by the Company
to or on account of Senior Indebtedness, it being understood that the provisions
of this Article 5 are, and are intended, solely for the purpose of defining the
relative rights of the Holders, on the one hand, and the holders of Senior
Indebtedness, on the other hand.

SECTION 5.4 OBLIGATIONS OF THE COMPANY UNCONDITIONAL.

        Nothing contained in this Article 5 or elsewhere in this Indenture or in
any Security is intended to or shall impair the obligation of the Company, which
is absolute and unconditional, to pay to the Holders the principal of and
interest on the Securities, as and when the same shall become due and payable in
accordance with the terms of the Securities, or to affect the relative rights of
the Holders and other creditors of the Company other than the holders of Senior
Indebtedness, nor shall anything herein or therein prevent the Trustee or any
Holder from exercising all remedies otherwise permitted by applicable law upon
the happening of an Event of Default under this Indenture, subject to the
provisions of Article 8, and the rights, if any, under this Article 5 of the
holders of Senior Indebtedness in respect of assets, whether in cash, property
or securities, of the Company received upon the exercise of any such remedy.

SECTION 5.5 COMPANY NOT TO MAKE PAYMENT WITH RESPECT TO SECURITIES IN CERTAIN
            CIRCUMSTANCES.

        Upon the occurrence of a Payment Default, unless and until the amount of
such Senior Indebtedness then due shall have been paid in full, or such default
shall have been cured or waived or shall have ceased to exist, the Company shall
not pay principal of, premium, if any (including the Make-Whole Payment, if
any), or interest on the Securities or any other amount due pursuant to this
Indenture or any Securities or make any deposit pursuant to Article 3 or Section
6.3 or 10.1 and shall not repurchase, redeem or otherwise retire any Securities
(collectively, "a Payment of the Securities").

        Unless Section 5.2 shall be applicable, upon (1) the occurrence of a
default on Senior Indebtedness (other than a Payment Default) that occurs and is
continuing that permits the holders of such Senior Indebtedness (or their
Representative or Representatives) to accelerate its maturity and (2) receipt by
the Company and the Trustee from the Senior Agent of written notice of such
occurrence and the imposition of a Payment Blockage Period hereunder, then the
Company shall not make any Payment of the Securities for a period (the "Payment
Blockage Period") commencing on the earlier of the date of receipt by the
Company or the Trustee of such notice from the Senior Agent and ending on the
earlier of (subject to any blockage of payments that may then be in effect under
subsection (a) of this Section) (x) the date 179 days after such date, (y) the
date such default shall have been cured or waived in writing or shall have
ceased to exist or such Senior Indebtedness shall have been discharged, or (z)
the date such Payment Blockage Period shall have been terminated by written
notice to the Company or the Trustee from the Senior Agent, after which, in case
of clause (x), (y) or (z), as the case may be, the Company shall resume making
any and all required payments. Notwithstanding any other provision of this
Agreement, only one Payment Blockage Period may be commenced within any


                                       50
<PAGE>   56
consecutive 365-day period, and no event of default with respect to any Senior
Indebtedness which existed or was continuing on the date of the commencement of
any Payment Blockage Period with respect to such Senior Indebtedness shall be,
or can be made, the basis for the commencement of a second Payment Blockage
Period whether or not within a period of 365 consecutive days unless such event
of default shall have been cured or waived for a period of not less than 90
consecutive days. In no event will a Payment Blockage Period extend beyond 179
days.

        In the event that, notwithstanding the foregoing provisions of this
Section 5.5, any Payment of the Securities shall be made by or on behalf of the
Company and received by the Trustee, any Holder or any Paying Agent (or, if the
Company is acting as its own Paying Agent, money for any such payment shall be
segregated and held in trust), which payment was prohibited by this Section 5.5,
then, unless and until the amount of Senior Indebtedness then due, as to which a
default shall have occurred, shall have been paid in full, or such default shall
have been cured or waived, such payment (subject, in each case, to the
provisions of Sections 5.6 and 5.7) shall be held in trust for the benefit of,
and shall be immediately paid over to, the holders of Senior Indebtedness or
their Representative or Representatives, ratably according to the aggregate
amounts remaining unpaid on account of the principal of and interest on the
Senior Indebtedness held or represented by each, for application to the payment
of all Senior Indebtedness remaining unpaid to the extent necessary to pay all
Senior Indebtedness in accordance with its terms, after giving effect to any
concurrent payment or distribution to or for the benefit of the holders of
Senior Indebtedness. The Company shall give prompt written notice to the Trustee
of any default under any Senior Indebtedness or under any agreement pursuant to
which Senior Indebtedness may have been issued.

SECTION 5.6 NOTICE TO TRUSTEE.

        The Company shall give prompt written notice to the Trustee of any fact
known to the Company which would prohibit the making of any payment to or by the
Trustee in respect of the Securities. Notwithstanding the provisions of this
Article 5 or any other provision of this Indenture, the Trustee shall not at any
time be charged with knowledge of the existence of any facts which would
prohibit the making of any payment to or by the Trustee, unless and until the
Trustee shall have received notice thereof from the Company or from the holder
or holders of Senior Indebtedness or from their Representative or
Representatives; and, prior to the receipt of any such notice, the Trustee,
subject to the provisions of Sections 9.1 and 9.2, shall be entitled to assume
conclusively that no such facts exist.

        The Trustee shall be entitled to rely on the delivery to it of a written
notice by a person representing himself to be a holder of Senior Indebtedness
(or a Representative of such holder) to establish that such notice has been
given by a holder of Senior Indebtedness or a Representative of any such holder.
In the event that the Trustee determines in good faith that further evidence is
required with respect to the right of any person as a holder of Senior
Indebtedness to participate in any payment or distribution pursuant to this
Article 5, the Trustee may request such person to furnish evidence to the
reasonable satisfaction of the Trustee as to the amount of Senior Indebtedness
held by such person, the extent to which such person is entitled to participate
in such payment or distribution and any other facts pertinent to the rights of
each person under this


                                       51
<PAGE>   57
Article 5, and if such evidence is not furnished, the Trustee may defer any
payment to such person pending judicial determination as to the right of such
person to receive such payment.

SECTION 5.7 APPLICATION BY TRUSTEE OF MONIES DEPOSITED WITH IT.

        Money or U.S. Government Obligations deposited in trust with the Trustee
pursuant to Sections 6.3 and 10.1 and not in violation of this Article 5 shall
be for the sole benefit of Securityholders and shall thereafter not be subject
to the subordination provisions of this Article 5. Otherwise, any deposit of
monies by the Company with the Trustee or any Paying Agent (whether or not in
trust) for the payment of the principal of or interest on any Securities shall
be subject to the provisions of Sections 5.1, 5.2, 5.3 and 5.5; except that, if
two Business Days prior to the date on which by the terms of this Indenture any
such monies may become payable for any purpose (including, without limitation,
the payment of either the principal of or interest on any Security), the Trustee
shall not have received with respect to such monies the notice provided for in
Section 5.6, then the Trustee or any Paying Agent shall have full power and
authority to receive such monies and to apply such monies to the purpose for
which they were received, and shall not be affected by any notice to the
contrary which may be received by it on or after such date. This Section 5.7
shall be construed solely for the benefit of the Trustee and the Paying Agent
and shall not otherwise affect the rights that holders of Senior Indebtedness
may have to recover any such payments from the Holders in accordance with the
provisions of this Article 5.

SECTION 5.8 SUBORDINATION RIGHTS NOT IMPAIRED BY ACTS OR OMISSIONS OF COMPANY OR
            HOLDERS OF SENIOR INDEBTEDNESS.

        No right of any present or future holders of any Senior Indebtedness to
enforce subordination, as herein provided, shall at any time in any way be
prejudiced or impaired by any act or failure to act on the part of the Company
or by any act or failure to act, in good faith, by any such holder, or by any
noncompliance by the Company with the terms, provisions and covenants of this
Indenture, regardless of any knowledge thereof which any such holder may have or
be otherwise charged with. The holders of any Senior Indebtedness may extend,
renew, modify or amend the terms of such Senior Indebtedness or any security
therefor and release, sell or exchange such security and otherwise deal freely
with the Company, all without affecting the liabilities and obligations of the
parties to this Indenture or the Holders. No amendment of this Article 5 or any
defined terms used herein or any other Sections referred to in this Article 5
which adversely affects the rights hereunder of holders of Senior Indebtedness,
shall be effective unless the holders of such Senior Indebtedness (required
pursuant to the terms of such Senior Indebtedness to give such consent) have
consented thereto.

SECTION 5.9 TRUSTEE TO EFFECTUATE SUBORDINATION.

        Each holder of a Security by his acceptance thereof authorizes and
directs the Trustee in his behalf to take such action as may be necessary or
appropriate to acknowledge and effectuate the subordination provided in this
Article 5 and appoints the Trustee his attorney-in-fact for any and all such
purposes.



                                       52
<PAGE>   58

SECTION 5.10 RIGHT OF TRUSTEE TO HOLD SENIOR INDEBTEDNESS.

        The Trustee, in its individual capacity, shall be entitled to all of the
rights set forth in this Article 5 in respect of any Senior Indebtedness at any
time held by it to the same extent as any other holder of Senior Indebtedness,
and nothing in this Indenture shall be construed to deprive the Trustee of any
of its rights as such holder.

SECTION 5.11 ARTICLE 5 NOT TO PREVENT EVENTS OF DEFAULT.

        The failure to make a Payment of the Securities by reason of any
provision in this Article 5 shall not be construed as preventing the occurrence
of an Event of Default under Section 8.1.

SECTION 5.12 NO FIDUCIARY DUTY CREATED TO HOLDERS OF SENIOR INDEBTEDNESS.

        Notwithstanding any other provision in this Article 5, the Trustee shall
not be determined to owe any fiduciary duty to the holders of Senior
Indebtedness by virtue of the provisions of this Article 5.

SECTION 5.13 ARTICLE APPLICABLE TO PAYING AGENTS.

        In case at any time any Paying Agent other than the Trustee shall have
been appointed by the Company and be then acting hereunder, the term "Trustee"
as used in this Article 5 shall in such case (unless the context shall otherwise
require) be construed as extending to and including such Paying Agent within its
meaning as fully for all intents and purposes as if such Paying Agent were named
in this Article 5 in addition to or in place of the Trustee; provided, however,
that Sections 5.6, 5.10 and 5.12 shall not apply to the Company if it acts as
Paying Agent.

SECTION 5.14 CERTAIN CONVERSION DEEMED PAYMENT.

        For the purposes of this Article only, (1) the issuance and delivery of
junior securities upon conversion of Securities in accordance with Article 4
shall not be deemed to constitute a payment or distribution on account of the
principal of or premium or interest on Securities or on account of the purchase
or other acquisition of Securities, and (2) the payment, issuance or delivery of
cash, property or securities (other than junior securities) upon conversion of a
Security shall be deemed to constitute payment on account of principal of such
Security. For the purposes of this Section, the term "junior securities" means
(a) shares of any stock of any class of the Company and (b) securities of the
Company which are subordinated in right of payment to all Senior Indebtedness
which may be outstanding at the time of issuance or delivery of such securities
to substantially the same extent as, or to a greater extent than, the Securities
are so subordinated as provided in this Article. Nothing contained in this
Article or elsewhere in this Indenture or in the Securities is intended to or
shall impair, as among the Company, its creditors other than holders of Senior
Indebtedness and the Holders of the Securities, the right, which is absolute and
unconditional, of the Holder of any Security to convert such Security in
accordance with Article 4.



                                       53
<PAGE>   59

                                   ARTICLE 6.

                                    COVENANTS


SECTION 6.1 PAYMENT OF SECURITIES.

        The Company covenants and agrees that it will duly and punctually pay or
cause to be paid the principal amount at maturity, Redemption Price (and, if
applicable, Make-Whole Payment), Repurchase Price and interest, in respect of
each of the Securities at the places, at the respective times and in the manner
provided herein and in the Securities. Each installment of interest on the
Securities may be paid by mailing checks for the interest payable to or upon the
written order of the holders of Securities entitled thereto as they shall appear
on the registry books of the Company; provided that with respect to any holder
of Securities with an aggregate principal amount equal to or in excess of $5
million, at the request of such holder in writing the Company shall pay interest
on such holder's Securities by wire transfer in immediately available funds.

SECTION 6.2 SEC REPORTS; 144A INFORMATION.

        The Company shall file all reports and other information and documents
which it is required to file with the SEC pursuant to Section 13 or 15(d) of the
Exchange Act, and within 15 days after it files them with the SEC, the Company
shall file copies of all such reports, information and other documents with the
Trustee. The Company will cause any quarterly and annual reports which it mails
to its stockholders to be mailed to the Holders of the Securities.

        In the event the Company is at any time no longer subject to the
reporting requirements of Section 13 or 15(d) of the Exchange Act, the Company
will prepare, for the first three quarters of each fiscal year, quarterly
financial statements substantially equivalent to the financial statements
required to be included in a report on Form 10-Q under the Exchange Act. The
Company will also prepare, on an annual basis, complete audited consolidated
financial statements including, but not limited to, a balance sheet, a statement
of income and retained earnings, a statement of cash flows and all appropriate
notes. All such financial statements will be prepared in accordance with
generally accepted accounting principles consistently applied, except for
changes with which the Company's independent accountants concur, and except that
quarterly statements may be subject to year-end adjustments. The Company will
cause a copy of such financial statements to be filed with the Trustee and
mailed to the Holders of the Securities within 50 days after the close for each
of the first three quarters of each fiscal year and within 95 days after the
close of each fiscal year. The Company will also comply with the other
provisions of TIA 314(a).

        At any time when the Company is not subject to Section 13 or 15(d) of
the Exchange Act, upon the request of a holder or beneficial owner of a
Security, the Company will promptly furnish or cause to be furnished Rule 144A
Information (as defined below) to such holder, to such beneficial owner or to a
prospective purchaser designated by such Securityholder or beneficial owner, as
the case may be, in order to permit compliance by such Securityholder or
beneficial owner with Rule 144A under the Securities Act in connection with the
resale of such Note by such Securityholder or beneficial owner; provided,
however, the Company shall not be



                                       54
<PAGE>   60

required to furnish such information in connection with any request made on or
after the date which is two years from the later of (i) the date such Note (or
any predecessor Note) was acquired from the Company or (ii) the date such Note
(or any predecessor Note) was last acquired from an "affiliate" of the Company
within the meaning of Rule 144 under the Securities Act. "Rule 144A Information"
shall be such information as is specified pursuant to Rule 144A(d)(4) under the
Securities Act (or any successor provision thereto).

SECTION 6.3 LIQUIDATION.

        Subject to the provisions of Article 5, insofar as they may be
applicable hereto, the Board of Directors or the stockholders of the Company may
not adopt a plan of liquidation which plan provides for, contemplates, or the
effectuation of which is preceded by (a) the sale, lease, conveyance or other
disposition of all or substantially all of the assets of the Company otherwise
than substantially as an entirety (Article 7 of this Indenture being the Article
which governs any such sale, lease, conveyance or other disposition
substantially as an entirety), and (b) the distribution of all or substantially
all of the proceeds of such sale, lease, conveyance or other disposition and of
the remaining assets of the Company to the holders of the capital stock of the
Company, unless the Company shall in connection with the adoption of such plan
make provision for, or agree that prior to making any liquidating distributions
to the holders of capital stock of the Company it will make provision for, the
satisfaction of the Company's obligations hereunder and under the Securities as
to the payment of principal and interest. The Company shall be deemed to have
made provision for such payments only if (1) the Company irrevocably deposits in
trust with the Trustee money or U.S. Government Obligations maturing as to
principal and interest in such amounts and at such times as are sufficient,
without consideration of any reinvestment of such interest, to pay the principal
of and interest on the Securities then outstanding to maturity and to pay all
other sums payable by it hereunder, or (2) there is an express assumption of the
due and punctual payment of the Company's obligations hereunder and under the
Securities and the performance and observance of all covenants and conditions to
be performed by the Company hereunder, by the execution and delivery of a
supplemental indenture in form reasonably satisfactory to the Trustee by a
person who acquires, or will acquire (otherwise than pursuant to a lease) a
portion of the assets of the Company, and which person will have Consolidated
Net Worth (immediately after the acquisition) equal to not less than the
Consolidated Net Worth of the Company (immediately preceding such acquisition),
and which is a corporation organized under the laws of the United States, any
State thereof or the District of Columbia; provided, however, that the Company
shall not make any liquidating distribution to the holders of capital stock of
the Company described in the first sentence of this Section 6.3 until after the
Company shall have certified to the Trustee with an Officers' Certificate at
least five days prior to the making of any liquidating distribution that it has
complied with the provisions of this Section 6.3.

SECTION 6.4 COMPLIANCE CERTIFICATES.

        The Company shall deliver to the Trustee within 120 days after the end
of each fiscal year of the Company, an Officers' Certificate as to the signer's
knowledge of the Company's compliance with all conditions and covenants on its
part contained in this Indenture and stating whether or not the signer knows of
any default or Event of Default. If such signer knows of such a default or Event
of Default, the Certificate shall describe the default or Event of Default and
the



                                       55
<PAGE>   61

efforts to remedy the same. For the purposes of this Section 6.4, compliance
shall be determined without regard to any grace period or requirement of notice
provided pursuant to the terms of this Indenture. The Certificate need not
comply with Section 12.4 hereof.

SECTION 6.5 NOTICE OF DEFAULTS.

        The Company will give notice to the Trustee, promptly upon becoming
aware thereof, of the existence of any Event of Default hereunder.

SECTION 6.6 PAYMENT OF TAXES AND OTHER CLAIMS.

        The Company will pay or discharge or cause to be paid or discharged,
before the same shall become delinquent, (1) all material taxes, assessments and
governmental charges levied or imposed upon the Company, directly or by reason
of its ownership of any Subsidiary or upon the income, profits or property of
the Company; and (2) all material lawful claims for labor, materials and
supplies, which, if unpaid, might by law become a lien upon the property of the
Company; provided, however, that the Company shall not be required to pay or
discharge or cause to be paid or discharged any such tax, assessment, charge or
claim whose amount, applicability or validity is being contested in good faith
by appropriate proceedings and for which adequate provision has been made.

SECTION 6.7 CORPORATE EXISTENCE.

        Subject to Section 6.3 and Article 7, the Company will do or cause to be
done all things necessary to preserve and keep in full force and effect its
corporate existence and rights (charter and statutory); provided, however, that
the Company shall not be required to preserve any right if the Company shall
determine that the preservation is no longer desirable in the conduct of the
Company's business and that the loss thereof is not, and will not be, adverse in
any material respect to the Holders.

SECTION 6.8 MAINTENANCE OF PROPERTIES.

        Subject to Section 6.3, the Company will cause all material properties
owned, leased or licensed in the conduct of its business to be maintained and
kept in good condition, repair and working order and supplied with all necessary
equipment and will cause to be made all necessary repairs, renewals,
replacements, betterments and improvements thereof and thereto, all as in the
judgment of the Company may be necessary so that the business carried on in
connection therewith may be properly and advantageously conducted at all times
while any Securities are outstanding; provided, however, that nothing in this
Section 6.8 shall prevent the Company from doing otherwise if, in the judgment
of the Company, the same is desirable in the conduct of the Company's business
and is not, and will not be, adverse in any material respect to the Holders.

SECTION 6.9 FURTHER INSTRUMENTS AND ACTS.

        Upon request of the Trustee, the Company will execute and deliver such
further instruments and do such further acts as may be reasonably necessary or
proper to carry out more effectively the purposes of this Indenture.



                                       56
<PAGE>   62

SECTION 6.10 MAINTENANCE OF OFFICE OR AGENCY.

        The Company will maintain in The City of New York an office or agency
where Securities may be presented or surrendered for payment or repurchase,
where Securities may be surrendered for registration of transfer or exchange and
where notices and demands to or upon the Company in respect of the Securities
and this Indenture may be served. The office of the agent of the Trustee in The
City of New York shall be such office or agency of the Company, unless the
Company shall designate and maintain some other office or agency for one or more
of such purposes. The Company will give prompt written notice to the Trustee of
any change in the location of any such office or agency. If at any time the
Company shall fail to maintain any such required office or agency or shall fail
to furnish the Trustee with the address thereof, such presentations, surrenders,
notices and demands may be made or served at the Corporate Trust Office of the
Trustee, and the Company hereby appoints the Trustee as its agent to receive all
such presentations, surrenders, notices and demands.

        The Company may from time to time designate one or more other offices or
agencies where the Securities may be presented or surrendered for any or all
such purposes and may from time to time rescind such designation; provided,
however, that no such designation or rescission shall in any manner relieve the
Company of its obligation to maintain an office or agency in The City of New
York for such purposes. The Company will give prompt written notice to the
Trustee of any such designation or rescission and any change in the location of
any such office or agency.

SECTION 6.11 RESALE OF CERTAIN SECURITIES; REPORTING ISSUER.

        During the period beginning on the last date of original issuance of the
Securities and ending on the date that is two years from such date, the Company
will not, and will use all reasonable efforts not to permit any of its
"affiliates" (as defined under Rule 144 under the Securities Act or any
successor provision thereto) to, resell (x) any Securities which constitute
"restricted securities" under Rule 144 or (y) any securities into which the
Securities have been converted under this Indenture which constitute "restricted
securities" under Rule 144, that in either case have been reacquired by any of
them. The Trustee shall have no responsibility in respect of the Company's
performance of its agreement in the preceding sentence.

SECTION 6.12 REGISTRATION RIGHTS.

        (a) The Company agrees that the Holders (and any Person that has a
beneficial interest in a Security) from time to time of Registrable Securities
(as such term is defined in the Registration Rights Agreement) are entitled to
the benefits of the Registration Rights Agreement. Pursuant to the Registration
Rights Agreement, the Company has agreed for the benefit of the Holders from
time to time of Registrable Securities, at the Company's expense, (i) to file
within 90 days after the first date of original issuance of the Securities, a
shelf registration statement (the "Shelf Registration Statement") with the
Commission with respect to resales of the Transfer Restricted Securities, (ii)
to use all reasonable efforts to cause such Shelf Registration Statement to be
declared effective by the Commission not later than 180 days after the first
date of original issuance of the Securities, and (iii) to use all reasonable
efforts to maintain such Shelf



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<PAGE>   63

Registration Statement continuously effective under the Securities Act subject
to and in accordance with the terms of the Registration Rights Agreement.

        Additional interest (the "Additional Interest") with respect to the
Securities shall be assessed if an Event (as defined in the Registration Rights
Agreement) occurs. Additional Interest shall accrue on the Securities over and
above the interest set forth in the title of the Securities from and including
the date on which any such Event shall occur, to but excluding the date on which
such Event has been cured (in the manner described in the Registration Rights
Agreement), at a rate of 0.50% per annum.

        (b) Any amounts of Additional Interest due pursuant to clause (a) of
this Section 6.12 shall be payable in cash on the regular interest payment
dates. The amount of Additional Interest shall be determined by multiplying the
applicable Additional Interest rate by the principal amount of the Securities,
multiplied by a fraction, the numerator of such period (determined on the basis
of a 360-day year comprised of twelve 30-day months), and the denominator of
which is 360.

        Whenever in this Indenture there is mentioned, in any context, the
payment of the principal of, premium, if any, or interest on, or in respect of,
any Security, such mention shall be deemed to include mention of the payment of
Additional Interest provided for in this Section to the extent that, in such
context, Additional Interest are, were or would be payable in respect thereof
pursuant to the provisions of this Section 6.12 and express mention of the
payment of Additional Interest (if applicable) in any provisions hereof shall
not be construed as excluding Additional Interest in those provisions hereof
where such express mention is not made.

SECTION 6.13 ADDITIONAL INTEREST.

        If Additional Interest is payable pursuant to the Registration Rights
Agreement, the Company shall deliver to the Trustee a certificate to that effect
stating (i) the amount of such Additional Interest that is payable and (ii) the
date on which such interest is payable. Unless and until a Trust Officer
receives at the Corporate Trust Office such a certificate, the Trustee may
assume without inquiry that no such interest is payable. If the Company has paid
Additional Interest directly to the Persons entitled to it, the Company shall
deliver to the Trustee a certificate setting forth the particulars of such
payment.

SECTION 6.14 STAY, EXTENSION AND USURY LAWS.

        The Company covenants (to the extent that it may lawfully do so) that it
will not at any time insist upon, plead, or in any manner whatsoever claim or
take the benefit or advantage of, any stay, extension or usury law wherever
enacted, now or at any time hereafter in force, which may affect the covenants
or the performance of this Indenture; and the Company (to the extent it may
lawfully do so) hereby expressly waives all benefit or advantage of any such
law, and covenants that it will not, by resort to any such law, hinder, delay or
impede the execution of any power herein granted to the Trustee, but will suffer
and permit the execution of every such power as though no such law had been
enacted.



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                                   ARTICLE 7.

                              SUCCESSOR CORPORATION


SECTION 7.1 WHEN COMPANY MAY MERGE, ETC.

        The Company shall not consolidate with or merge into any other Person,
or convey, transfer or lease its properties and assets substantially as an
entirety to any Person, and shall not permit any Person (other than a Subsidiary
wholly-owned by the Company) to consolidate with or merge into the Company or
convey, transfer or lease its properties and assets substantially as an entirety
to the Company, unless:

        (a) in case the Company shall consolidate with or merge into another
Person or convey, transfer or lease its properties and assets substantially as
an entirety to any Person, the Person formed by such consolidation or into which
the Company is merged or the Person which acquires by conveyance or transfer, or
which leases, the properties and assets of the Company substantially as an
entirety shall be a corporation, partnership or trust, shall be organized and
validly existing under the laws of the United States of America, any State
thereof or the District of Columbia and shall expressly assume, by an indenture
supplemental thereto, executed and delivered to the Trustee, in form
satisfactory to the Trustee, the due and punctual payment of the principal of
(and premium, if any) and interest on all the Securities and the performance or
observance of every covenant of this Indenture on the part of the Company to be
performed or observed and shall have provided for conversion rights in
accordance with Section 4.12;

        (b) immediately after giving effect to such transaction and treating any
indebtedness which becomes an obligation of the Company or a Subsidiary as a
result of such transaction as having been incurred by the Company or such
Subsidiary at the time of such transaction, no Event of Default, and no event
which, after notice or lapse of time or both, would become an Event of Default,
shall have happened and be continuing; and

        (c) the Company has delivered to the Trustee an Officers' Certificate
and an Opinion of Counsel, each stating that such consolidation, merger,
conveyance, transfer or lease and, if a supplemental indenture is required in
connection with such transaction, such supplemental indenture comply with this
Article and that all conditions precedent herein provided for relating to such
transaction have been complied with.

SECTION 7.2 SUCCESSOR CORPORATION SUBSTITUTED.

        Upon any consolidation of the Company with, or merger of the Company
into, any other Person or any conveyance, transfer or lease of the properties
and assets of the Company substantially as an entirety in accordance with
Section 7.1, the successor person formed by such consolidation or into which the
Company is merged or to which such conveyance, transfer or lease is made shall
succeed to, and be substituted for, and may exercise every right and power of,
the Company under this Indenture with the same effect as if such successor
Person had been named as the Company herein, and thereafter, except in the case
of a lease, the predecessor Person shall be relieved of all obligations and
covenants under this Indenture and the Notes.



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<PAGE>   65

                                   ARTICLE 8.

                              DEFAULT AND REMEDIES

SECTION 8.1 EVENTS OF DEFAULT.

        An "Event of Default" occurs if:

        (1) the Company defaults in the payment of interest (including
Additional Interest) on any Security when the same becomes due and payable and
the default continues for a period of 30 days;

        (2) the Company defaults in the payment of the principal of any Security
when the same becomes due and payable at maturity, upon redemption or otherwise;

        (3) the Company fails to comply with any other covenant, warranty or
agreement contained in the Securities or this Indenture and the default
continues for the period and after the notice specified below;

        (4) the Company or any Subsidiary shall fail to pay when due and owing
principal of, premium, if any, or interest on any indebtedness for borrowed
money or upon acceleration of such indebtedness under the terms of the
instruments evidencing such indebtedness (provided, however, such acceleration
is not withdrawn, cancelled or otherwise annulled within 10 days following the
occurrence of such acceleration); provided, however, no such Event of Default
shall exist under this Section 8.1(4) unless the aggregate amount of such
principal, premium, if any, and interest is in excess of $10,000,000;

        (5) the Company or any Subsidiary pursuant to or within the meaning of
any Bankruptcy Law:

            A. commences a voluntary case or proceeding;

            B. consents to the entry of an order for relief against it in an
involuntary case or proceeding;

            C. consents to the appointment of a Custodian of it or for all or
substantially all of its property; or

            D. makes a general assignment for the benefit of its creditors; or

        (6) a court of competent jurisdiction enters an order or decree under
any Bankruptcy Law that:

            A. is for relief against the Company or any Subsidiary in an
involuntary case or proceeding;

            B. appoints a Custodian of the Company or any Subsidiary or for all
or substantially all of the property of any of them; or



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<PAGE>   66

            C. orders the liquidation of the Company or any Subsidiary;

        and in each case the order or decree remains unstayed and in effect for
60 days.

        The term "Bankruptcy Law" means Title 11, U.S. Code or any similar
Federal or state law for the relief of debtors. For purposes of this Section
8.1, the term "Custodian" means any receiver, trustee, assignee, liquidator,
sequestrator or similar official under any Bankruptcy Law.

        A default under clause (3) is not an Event of Default until the Trustee
notifies the Company, or the Holders of at least 25% in principal amount of the
Securities then outstanding notify the Company and the Trustee, of the default,
and the Company does not cure the default within 60 days after receipt of such
notice. The notice given pursuant to this Section 8.1 must specify the default,
demand that it be remedied and state that the notice is a "Notice of Default."
When a default is cured, it ceases.

        Subject to the provisions of Sections 9.1 and 9.2, the Trustee shall not
be charged with knowledge of any Event of Default unless written notice thereof
shall have been given to a Trust Officer at the Corporate Trust Office of the
Trustee by the Company, the Paying Agent, any Holder or an agent of any Holder.

SECTION 8.2 ACCELERATION.

        If an Event of Default (other than an Event of Default specified in
Section 8.1(5) or (6)) occurs and is continuing, the Trustee may, by notice to
the Company, or the Holders of at least 25% in principal amount of the
Securities then outstanding may, by notice to the Company and the Trustee, and
the Trustee shall, upon the request of such Holders, declare all unpaid
principal of and accrued interest to the date of acceleration on the Securities
then outstanding (if not then due and payable) to be due and payable upon any
such declaration, and the same shall become and be immediately due and payable.
If an Event of Default specified in Section 8.1(5) or (6) occurs, all unpaid
principal of and accrued interest on the Securities then outstanding shall ipso
facto become and be immediately due and payable without any declaration or other
act on the part of the Trustee or any Securityholder.

        The Holders of a majority in principal amount of the Securities then
outstanding by notice to the Trustee may rescind an acceleration and its
consequences if (i) all existing Events of Default, other than the nonpayment of
the principal of and accrued interest on the Securities which has become due
solely by such declaration of acceleration, have been cured or waived; (ii) the
Company has paid or deposited with the Trustee a sum sufficient to pay (a) all
overdue interest on the Securities; (b) the principal of any Security which has
become due otherwise then by such declaration of acceleration, and (c) to the
extent the payment of such interest is lawful, interest on overdue installments
of interest and overdue principal, which has become due otherwise than by such
declaration of acceleration; (iii) the rescission would not conflict with any
judgment or decree of a court of competent jurisdiction; and (iv) all payments
due to the Trustee and any predecessor Trustee under Section 9.7 have been made.
No such rescission shall affect any subsequent default or impair any right
consequent thereon. Anything herein contained to the contrary notwithstanding,
in the event of any acceleration pursuant to this Section 8.2, the Company shall
not be obligated to pay any premium which it would have had to pay if it had



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then elected to redeem the Securities pursuant to paragraph 5 or 6 of the
Securities, except in the case of any Event of Default occurring by reason of
any willful action (or inaction) taken (or not taken) by or on behalf of the
Company with the intention of avoiding payment of the premium which it would
have had to pay if it had then elected to redeem the Securities pursuant to
paragraph 5 or 6 of the Securities, in which case an equivalent premium shall
also become and be immediately due and payable to the extent permitted by law.

SECTION 8.3 OTHER REMEDIES.

        In case of an Event of Default hereunder, the Trustee may in its
discretion proceed to protect and enforce the rights vested in it by this
Indenture by such appropriate judicial proceedings as the Trustee shall deem
most effectual to protect and enforce any of such rights, either by suit in
equity or by action at law or by proceeding in bankruptcy or otherwise, whether
for the specific enforcement of any covenant or agreement contained in this
Indenture or in aid of the exercise of any power granted in this Indenture, or
to enforce any other legal or equitable right vested in the Trustee by this
Indenture or by law.

        The Trustee may maintain a proceeding even if it does not possess any of
the Securities or does not produce any of them in the proceeding. A delay or
omission by the Trustee or any Securityholder in exercising any right or remedy
accruing upon an Event of Default shall not impair the right or remedy or
constitute a waiver of or acquiescence in the Event of Default. No remedy is
exclusive of any other remedy. All available remedies are cumulative to the
extent permitted by law.

SECTION 8.4 WAIVER OF DEFAULTS AND EVENTS OF DEFAULT.


        Subject to Section 8.7, the Holders of a majority in principal amount of
the Securities then outstanding by notice to the Trustee may waive an existing
default or Event of Default and its consequences, except a default in the
payment of the principal of (or premium, if any) or interest on any Security as
specified in clauses (1) and (2) of Section 8.1, or a default in respect of a
covenant or provision hereof which cannot be modified or amended pursuant to
Section 11.2 without the consent of the holder of each Note affected thereby.
When a default or Event of Default is waived, it is cured and ceases.

SECTION 8.5 CONTROL BY MAJORITY.

        The Holders of a majority in principal amount of the Securities then
outstanding may direct the time, method and place of conducting any proceeding
for any remedy available to the Trustee or exercising any trust or power
conferred on it. However, the Trustee may refuse to follow any direction that
conflicts with law or this Indenture; provided that the Trustee may take any
other action deemed proper by the Trustee which is not inconsistent with such
direction.

SECTION 8.6 LIMITATION ON SUITS.

        A Securityholder may not pursue any remedy with respect to this
Indenture or the Securities (except actions for payment of overdue principal or
interest or for the conversion of the Securities pursuant to Article 4) unless:



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        (1) the Holder gives to the Trustee written notice of a continuing Event
of Default;

        (2) the Holders of at least 25% in principal amount of the then
outstanding Securities make a written request to the Trustee to pursue the
remedy;

        (3) such Holder or Holders offer to the Trustee indemnity reasonably
satisfactory to the Trustee against any loss, liability or expense;

        (4) the Trustee does not comply with the request within 60 days after
receipt of the request and the offer of indemnity; and

        (5) no direction inconsistent with such written request has been given
to the Trustee during such 60-day period by the Holders of a majority in
principal amount of the Securities then outstanding.

        A Securityholder may not use any provision of this Indenture to
prejudice the rights of another Securityholder or to obtain a preference or
priority over such other Securityholder, or to enforce any rights under this
Indenture other than in the manner herein provided and for the equal and ratable
benefit of all the Securityholders.

SECTION 8.7 RIGHTS OF HOLDERS TO RECEIVE PAYMENT.

        Notwithstanding any other provision of this Indenture (but subject to
Article 5 hereof), the right of any Holder of a Security to receive payment of
principal of (and premium, if any) and interest on the Security, on or after the
respective dates on which such payments are due as expressed in the Security, or
to convert the Security, or to bring suit for the enforcement of any such
payment on or after such respective dates, is absolute and unconditional and
shall not be impaired or affected without the consent of the Holder.

SECTION 8.8 COLLECTION SUIT BY TRUSTEE.

        If an Event of Default in the payment of principal or interest specified
in Section 8.1(1) or (2) occurs and is continuing, the Trustee may recover
judgment in its own name and as trustee of an express trust against the Company
or another obligor on the Securities for the whole amount of principal and
accrued interest remaining unpaid, together with interest on overdue principal
and, to the extent that payment of such interest is lawful, interest on overdue
installments of interest, in each case at the rate per annum borne by the
Securities and such further amount as shall be sufficient to cover the costs and
expenses of collection, including the reasonable compensation, expenses,
disbursements and advances of the Trustee, its agents and counsel.

SECTION 8.9 TRUSTEE MAY FILE PROOFS OF CLAIM.

        The Trustee may file such proofs of claim and other papers or documents
as may be necessary or advisable in order to have the claims of the Trustee
(including any claim for the reasonable compensation, expenses, disbursements
and advances of the Trustee, its agents and counsel) and the Securityholders
allowed in any judicial proceedings relative to the Company (or any other
obligor on the Securities), its creditors or its property and shall be entitled
and empowered to collect and receive any monies or other property payable or
deliverable on any



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such claims and to distribute the same, and any Custodian in any such judicial
proceeding is hereby authorized by each Securityholder to make such payments to
the Trustee and, in the event that the Trustee shall consent to the making of
such payments directly to the Securityholders, to pay to the Trustee any amount
due to it for the reasonable compensation, expenses, disbursements and advances
of the Trustee, its agents and counsel, and any other amounts due the Trustee
under Section 9.7, and to the extent that such payment of the reasonable
compensation, expenses, disbursements and advances in any such proceedings shall
be denied for any reason, payment of the same shall be secured by a lien on, and
shall be paid out of, any and all distributions, dividends, monies, securities
and other property which the Securityholders may be entitled to receive in such
proceedings, whether in liquidation or under any plan of reorganization or
arrangement or otherwise. Nothing herein contained shall be deemed to authorize
the Trustee to authorize or consent to or the Trustee to authorize or accept or
adopt on behalf of any Securityholder any plan of reorganization, arrangement,
adjustment or composition affecting the Securities or the rights of any Holder
thereof, or to authorize the Trustee to vote in respect of the claim of any
Securityholder in any such proceeding.

SECTION 8.10 PRIORITIES.

        Subject to Article 5, if the Trustee collects any money pursuant to this
Article 8, it shall pay out the money in the following order:

        First, to the Trustee for amounts due under Section 9.7;

        Second, to Securityholders for amounts due and unpaid on the Securities
for principal and interest, ratably, without preference or priority of any kind,
according to the amounts due and payable on the Securities for principal and
interest, respectively; and

        Third, to the Company.

        The Trustee may fix a record date and payment date for any payment to
Securityholders pursuant to this Section 8.10.

SECTION 8.11 UNDERTAKING FOR COSTS.

        In any suit for the enforcement of any right or remedy under this
Indenture or in any suit against the Trustee for any action taken or omitted by
it as Trustee, a court in its discretion may require the filing by any party
litigant in the suit of an undertaking to pay the costs of the suit, and the
court in its discretion may assess reasonable costs, including reasonable
attorneys' fees, against any party litigant in the suit, having due regard to
the merits and good faith of the claims or defenses made by the party litigant.
This Section 8.11 does not apply to a suit made by the Trustee, a suit by a
Holder pursuant to Section 8.7, or a suit by any Holder, or group of Holders, of
more than 10% in principal amount of the Securities then outstanding.

SECTION 8.12 RESTORATION OF RIGHTS AND REMEDIES.

        If the Trustee or any Securityholder has instituted any proceeding to
enforce any right or remedy under this Indenture and such proceeding has been
discontinued or abandoned for any



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reason, or has been determined adversely to the Trustee or to such
Securityholder, then and in every such case, subject to any determination in
such proceeding, the Company, the Trustee and the Securityholders shall be
restored severally and respectively to their former positions hereunder and
thereafter all rights and remedies of the Trustee and the Securityholders shall
continue as though no such proceeding had been instituted.

SECTION 8.13 RIGHTS AND REMEDIES CUMULATIVE.

        Except as otherwise provided with respect to the replacement or payment
of mutilated, destroyed, lost or stolen Securities in the last paragraph of
Section 2.7, no right or remedy herein conferred upon or reserved to the Trustee
or to the Securityholders is intended to be exclusive of any other right or
remedy, and every right and remedy shall, to the extent permitted by law, be
cumulative and in addition to every other right and remedy given hereunder or
now or hereafter existing at law or in equity or otherwise. The assertion or
employment of any right or remedy hereunder, or otherwise, shall not prevent the
concurrent assertion or employment of any other appropriate right or remedy.

SECTION 8.14 DELAY OR OMISSION NOT WAIVER.

        No delay or omission of the Trustee or of any Securityholder to exercise
any right or remedy accruing upon any Event of Default shall impair any such
right or remedy or constitute a waiver of any such Event of Default or an
acquiescence therein. Every right and remedy given by this Article or by law to
the Trustee or to the Securityholders may be exercised from time to time, and as
often as may be deemed expedient, by the Trustee or by the Securityholders, as
the case may be.

                                   ARTICLE 9.

                                     TRUSTEE

SECTION 9.1 DUTIES OF TRUSTEE.

        (a) If an Event of Default has occurred and is continuing, the Trustee
shall exercise such of the rights and powers vested in it by this Indenture and
use the same degree of care and skill in their exercise as a prudent person
would exercise or use under the circumstances in the conduct of his own affairs.

        (b) Except during the continuance of an Event of Default:

        (1) the Trustee need perform only those duties as are specifically set
forth in this Indenture and no others; and

        (2) in the absence of bad faith on its part, the Trustee may
conclusively rely, as to the truth of the statements and the correctness of the
opinions expressed therein, upon certificates or opinions furnished to the
Trustee and conforming to the requirements of this Indenture. The Trustee,
however, shall examine the certificates and opinions to determine whether or not
they conform to the requirements of this Indenture.



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        (c) The Trustee may not be relieved, and no provision of this Indenture
shall be construed to relieve the Trustee, from liability for its own negligent
action, its own negligent failure to act, or its own willful misconduct, except
that:

        (1) this paragraph does not limit the effect of paragraph (b) of this
Section 9.1;

        (2) the Trustee shall not be liable for any error of judgment made in
good faith by a Trust Officer, unless it is proved that the Trustee was
negligent in ascertaining the pertinent facts; and

        (3) the Trustee shall not be liable with respect to any action it takes
or omits to take in good faith in accordance with a direction received by it
pursuant to Section 8.5.

        (d) The Trustee may refuse to perform any duty or exercise any right or
power unless it receives indemnity reasonably satisfactory to it against any
loss, liability, expense or fee.

        (e) Every provision of this Indenture that in any way relates to the
Trustee is subject to paragraphs (a), (b), (c) and (d) of this Section 9.1.

        (f) The Trustee shall not be liable for interest on any money received
by it except as the Trustee may agree in writing with the Company. Money held in
trust by the Trustee need not be segregated from other funds except to the
extent required by law.

SECTION 9.2 RIGHTS OF TRUSTEE.

        Subject to Section 9.1:

        (a) The Trustee may rely on any document believed by it to be genuine
and to have been signed or presented by the proper person. The Trustee need not
investigate any fact or matter stated in the document.

        (b) Whenever in the administration of this Indenture the Trustee shall
deem it desirable that a matter be proved or established prior to taking,
suffering or omitting any action hereunder, it may require an Officers'
Certificate or an Opinion of Counsel, which shall conform to Section 12.4(b).
The Trustee shall not be liable for any action it takes or omits to take in good
faith in reliance on such Certificate or Opinion.

        (c) The Trustee may act through its agents and shall not be responsible
for the misconduct or negligence of any agent appointed with due care.

        (d) The Trustee shall not be liable for any action it takes or omits to
take in good faith which it believes in good faith to be authorized or within
its rights or powers.

        (e) The Trustee may consult with counsel and the advice or opinion of
such counsel as to matters of law that shall be full and complete authorization
and protection in respect of any action taken, omitted or suffered by it
hereunder in good faith and in accordance with the advice or opinion of such
counsel.



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SECTION 9.3 INDIVIDUAL RIGHTS OF TRUSTEE.

        The Trustee in its individual or any other capacity may become the owner
or pledgee of Securities and may otherwise deal with the Company or an affiliate
of the Company with the same rights it would have if it were not Trustee. Any
Agent may do the same with like rights. However, the Trustee is subject to
Sections 9.10 and 9.11.

SECTION 9.4 TRUSTEE'S DISCLAIMER.

        The Trustee makes no representation as to the validity or adequacy of
this Indenture or the Securities, it shall not be accountable for the Company's
use of the proceeds from the Securities, and it shall not be responsible for any
statement in the Securities other than its certificate of authentication.

SECTION 9.5 NOTICE OF DEFAULT OR EVENTS OF DEFAULT.

        If a default or an Event of Default occurs and is continuing and if it
is known to the Trustee, the Trustee shall mail to each Securityholder notice of
the default or Event of Default within 90 days after it occurs. Except in the
case of a default or an Event of Default in payment of the principal of or
interest on any Security, the Trustee may withhold the notice if and so long as
a committee of its Trust Officers in good faith determines that withholding the
notice is in the interest of Securityholders.

SECTION 9.6 REPORTS BY TRUSTEE TO HOLDERS.

        If such report is required by TIA 313, within 60 days after each May 15,
beginning with the May 15 following the date of this Indenture, the Trustee
shall mail to each Securityholder a brief report dated as of such May 15 that
complies with TIA 313(a). The Trustee also shall comply with TIA 313(b) (2) and
(c).

        A copy of each report at the time of its mailing to Securityholders
shall be mailed to the Company and filed with the SEC and each stock exchange,
if any, on which the Securities are listed. The Company shall notify the Trustee
whenever the Securities become listed on any stock exchange and any changes in
the stock exchanges on which the Securities are listed.

SECTION 9.7 COMPENSATION AND INDEMNITY.

        The Company shall pay to the Trustee from time to time reasonable
compensation for its services (which compensation shall not be limited by any
provision of law in regard to the compensation of a trustee of an express
trust). The Company shall reimburse the Trustee upon request for all reasonable
disbursements, expenses and advances incurred or made by it. Such expenses may
include the reasonable compensation, disbursements and expenses of Trustee's
agents and counsel.

        The Company shall indemnify the Trustee for, and hold it harmless
against, any loss, liability or expense incurred by it in connection with its
duties under this Indenture or any action or failure to act as authorized or
within the discretion or rights or powers conferred upon the Trustee hereunder.
The Trustee shall notify the Company promptly of any claim asserted against



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the Trustee for which it may seek indemnity. The Trustee shall have the option
of undertaking the defense of such claims; provided, however, that if the
Trustee opts not to defend itself, the Trustee may have separate counsel and the
Company shall pay the reasonable fees and expenses of such counsel. The Company
need not pay for any settlement without its written consent.

        The Company need not reimburse the Trustee for any expense or indemnify
it against any loss or liability incurred by it through its own negligent
action, failure to act or willful misconduct.

        When the Trustees incurs expenses or renders services after an Event of
Default specified in Section 8.1(6) or (7) occurs, the expenses and the
compensation for the services are intended to constitute expenses of
administration under any Bankruptcy Law.

SECTION 9.8 REPLACEMENT OF TRUSTEE.

        The Trustee may resign by so notifying the Company; provided, however,
no such resignation shall be effective until a successor Trustee has accepted
its appointment pursuant to this Section 9.8. The Holders of a majority in
principal amount of the Securities then outstanding may remove the Trustee by so
notifying the Trustee and may appoint a successor Trustee with the Company's
written consent. The Company may remove the Trustee if:

        (1) the Trustee fails to comply with Section 9.10;

        (2) the Trustee is adjudged a bankrupt or an insolvent;

        (3) a receiver or other public officer takes charge of the Trustee or
its property; or

        (4) the Trustee becomes incapable of acting as trustee.

        If the Trustee resigns or is removed or if a vacancy exists in the
office of Trustee for any reason, the Company shall promptly appoint a successor
Trustee.

        If a successor Trustee does not take office within 45 days after the
retiring Trustee resigns or is removed, the retiring Trustee, the Company or the
Holders of 10% in principal amount of the Securities then outstanding may
petition any court of competent jurisdiction for the appointment of a successor
Trustee.

        If the Trustee fails to comply with Section 9.10 any Securityholder may
petition any court of competent jurisdiction for the removal of the Trustee and
the appointment of a successor Trustee.

        A successor Trustee shall deliver a written acceptance of its
appointment to the retiring Trustee and to the Company. Immediately after that,
the retiring Trustee shall transfer all property held by it as Trustee to the
successor Trustee and be released from its obligations (exclusive of any
liabilities Trustee may have incurred while acting as Trustee) hereunder, the
resignation or removal of the retiring Trustee shall become effective, and the
successor Trustee shall have all the rights, powers and duties of the Trustee
under this Indenture. A successor Trustee shall mail notice of its succession to
each Securityholder.



                                       68
<PAGE>   74

        Notwithstanding replacement of the Trustee pursuant to this Section 9.8,
the Company's obligations under Section 9.7 hereof shall continue for the
benefit of the retiring Trustee.

SECTION 9.9 SUCCESSOR TRUSTEE BY MERGER, ETC.

        If the Trustee consolidates with, merges or converts into, or transfers
all or substantially all of its corporate trust assets (including the
administration of this Indenture) to, another corporation, the resulting,
surviving or transferee corporation without any further act shall be the
successor Trustee, provided such transferee corporation shall qualify and be
eligible under Section 9.10.

SECTION 9.10 ELIGIBILITY; DISQUALIFICATION.

        There shall at all times be a Trustee hereunder which shall be a
corporation organized and doing business under the laws of the United States of
America, any State thereof or the District of Columbia, authorized under such
laws to exercise corporate trust process, having (together with any Person
directly or indirectly controlling the Trustee) a combined capital and surplus
of at least $25,000,000, subject to supervision or examination by federal or
state authority. If such corporation publishes reports of condition at least
annually, pursuant to law or to the requirements of said supervising or
examining authority, then for the purposes of this Section, the combined capital
and surplus of such corporation shall be deemed to be its combined capital and
surplus as set forth in its most recent report of condition so published. If at
any time the Trustee shall cease to be eligible in accordance with the
provisions of this Section, it shall resign immediately in the manner and with
the effect specified above in this Article.

SECTION 9.11 PREFERENTIAL COLLECTION OF CLAIMS AGAINST COMPANY.

        The Trustee shall comply with TIA 311(a), excluding any creditor
relationship listed in TIA 311(b). A trustee who has resigned or been removed
shall be subject to TIA 311(a) to the Government Obligations in accordance with
Section 10.1; provided, however, that if the Company has made any payment of the
principal of or premium (including the Make-Whole Payment, if any) or interest
on any Securities because of the reinstatement of its obligations, the Company
shall be subrogated to the rights of the Holders of such Securities to receive
any such payment from the money or U.S. Government Obligations held by the
Trustee or the Paying Agent.

                                  ARTICLE 10.

                     SATISFACTION AND DISCHARGE OF INDENTURE

SECTION 10.1 TERMINATION OF COMPANY'S OBLIGATIONS.

        The Company may terminate all of its obligations under the Securities
and this Indenture (except those obligations referred to in the immediately
succeeding paragraph) if all Securities previously authenticated and delivered
(other than destroyed, lost or stolen Securities which have been replaced or
paid or Securities for whose payment money has theretofore been held in trust
and thereafter repaid to the Company, as provided in Section 10.3) have been
delivered to the



                                       69
<PAGE>   75

Trustee for cancellation and the Company has paid all sums payable by it
hereunder, or if the Company irrevocably deposits in trust with the Trustee
money or U.S. Government Obligations maturing as to principal and interest in
such amounts and at such times as are sufficient, without consideration of any
reinvestment of such interest, to pay the principal of and premium, if any
(including the Make-Whole Payment, if any), and interest on the Securities then
outstanding to maturity or to the date fixed for redemption and to pay all other
sums payable by it hereunder. The Company may make an irrevocable deposit
pursuant to this Section 10.1 only if at such time it is not prohibited from
doing so under the provisions of Article 5 and the Company shall have delivered
to the Trustee and any such Paying Agent an Officers' Certificate to that effect
and that all other conditions to such deposit have been complied with.

        The Company's obligations in paragraphs 9 and 13 of the Securities, in
Sections 6.1, 6.2, 9.7, 9.8 and 10.4, and in Articles 2 and 4 shall survive
until the Securities are no longer outstanding. Thereafter, the Company's
obligations in such paragraph 13 and in Section 9.7 shall survive.

        After such irrevocable deposit, the Trustee upon request shall
acknowledge in writing the discharge of the Company's obligations under the
Securities and this Indenture, except for those surviving obligations specified
above.

        "U.S. Government Obligations" means direct non-callable obligations of,
or non-callable obligations guaranteed by, the United States of America for the
payment of which guarantee or obligation the full faith and credit of the United
States is pledged.

SECTION 10.2 APPLICATION OF TRUST MONEY.

        The Trustee or the Paying Agent shall hold in trust, for the benefit of
the Holders, money or U.S. Government Obligations deposited with it pursuant to
Section 10.1, and shall apply the deposited money and the money from U.S.
Government Obligations in accordance with this Indenture to the payment of the
principal of and interest on the Securities. Money and U.S. Government
Obligations so held in trust and deposited in compliance with Section 10.1 and
Article 5 shall not be subject to the subordination provisions of Article 5.

SECTION 10.3 REPAYMENT TO COMPANY.

        Subject to Section 10.1, the Trustee and the Paying Agent shall promptly
pay to the Company upon request any excess money or U.S. Government Obligations
held by them at any time.

        The Trustee and the Paying Agent shall pay to the Company upon request
any money held by them for the payment of principal or interest that remains
unclaimed for two years after a right to such money has matured; provided,
however, that the Trustee or such Paying Agent, before being required to make
any such payment, may at the expense of the Company cause to be published once
in a newspaper of general circulation in The City of New York or mail to each
Holder entitled to such money notice that such money remains unclaimed and that
after a date specified therein, which shall be at least 30 days from the date of
such publication or mailing, any unclaimed balance of such money then remaining
will be repaid to the Company. After that,



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<PAGE>   76

Holders entitled to money must look to the Company for payment unless an
abandoned property law designates another person.

SECTION 10.4 REINSTATEMENT.

        If the Trustee or the Paying Agent is unable to apply any money or U.S.
Government Obligations in accordance with Section 10.1 by reason of any legal
proceeding or by reason of any order or judgment of any court or governmental
authority enjoining, restraining or otherwise prohibiting such application, the
Company's obligations under this Indenture and the Securities shall be revived
and reinstated as though no deposit had occurred pursuant to Section 10.1 until
such time as the Trustee or Paying Agent is permitted to apply all such money or
U.S. Government Obligations in accordance with Section 10.1; provided, however,
that if the Company has made any payment of the principal of or premium
(including the Make-Whole Payment, if any) or interest on any Securities because
of the reinstatement of its obligations, the Company shall be subrogated to the
rights of the Holders of such Securities to receive any such payment from the
money or U.S. Government Obligations held by the Trustee or the Paying Agent.

                                  ARTICLE 11.

                       AMENDMENTS, SUPPLEMENTS AND WAIVERS

SECTION 11.1 WITHOUT CONSENT OF HOLDERS.

        The Company and the Trustee may amend or supplement this Indenture or
the Securities without notice to or consent of any Securityholder:

        (a) to comply with Sections 4.12, 6.3 and 7.1;

        (b) to cure any ambiguity, omission, defect or inconsistency, or to make
any other change that does not adversely affect the rights of any
Securityholder;

        (c) to make provisions with respect to the conversion right of the
Holders pursuant to Section 4.6(c);

        (d) to evidence and provide for the acceptance of appointment hereunder
by a successor Trustee with respect to the Securities; or

        (e) to comply with the provisions of the TIA or with any requirement of
the SEC arising solely as a result of the qualification of this Indenture under
the TIA.

SECTION 11.2 WITH CONSENT OF HOLDERS.

        The Company and the Trustee may amend or supplement this Indenture or
the Securities without notice to any Securityholder but with the written consent
of the Holders of a majority in aggregate principal amount of the Securities
then outstanding. The Holders of a majority in aggregate principal amount of the
Securities then outstanding may waive compliance in a particular instance by the
Company with any provision of this Indenture or the Securities without



                                       71
<PAGE>   77

notice to any Securityholder. Subject to Section 11.4, without the written
consent of each Securityholder affected, however, an amendment, supplement or
waiver, including a waiver pursuant to Section 8.4, may not:

        (a) change the stated maturity date of the principal of, or any
installment of interest on, any Security;

        (b) reduce the principal amount of, or the rate of interest on, or any
premium (including the Make-Whole Payment, if any) payable on, any Security,
whether upon acceleration, redemption or otherwise;

        (c) change the currency for payment of principal of, or premium
(including the Make-Whole Payment, if any) or interest (including Additional
Interest) on any Security;

        (d) impair the right to institute suit for the enforcement of any
payment of principal of, or premium or interest on any Security when due;

        (e) adversely affect the conversion rights provided in Article 4 hereof;

        (f) modify the provisions of Article 5 hereof with respect to the
subordination of the Securities in a manner adverse to the holders;

        (g) modify the obligation of the Company hereunder to purchase
Securities upon a Change of Control in a manner adverse to the holders;

        (h) reduce the percentage of principal amount of Securities necessary to
modify or amend this Indenture or to consent to any waiver provided for in this
Indenture;

        (i) waive a default in the payment of the principal of or premium
(including the Make-Whole Payment, if any) or interest (including Additional
Interest) on any Security; or

        (j) make any changes in Section 8.4, 8.7 or this sentence.

        It shall not be necessary for the consent of the Holders under this
Section to approve the particular form of any proposed amendment, supplement or
waiver, but it shall be sufficient if such consent approves the substance
thereof.

        After an amendment, supplement or waiver under this Section becomes
effective, the Company shall mail to the Holders affected thereby a notice
briefly describing the amendment, supplement or waiver. Any failure of the
Company to mail such notice, or any defect therein, shall not, however, in any
way impair or affect the validity of any such amendment, supplement or waiver.

        An amendment under this Section 11.2 may not make any change that
adversely affects the rights under Article 5 of any holder of an issue of Senior
Indebtedness unless the holders of that issue, pursuant to its terms, consent to
the change.



                                       72
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SECTION 11.3 COMPLIANCE WITH TRUST INDENTURE ACT.

        Every amendment to or supplement of this Indenture or the Securities
shall comply with TIA as in effect at the date of such amendment or supplement.

SECTION 11.4 REVOCATION AND EFFECT OF CONSENTS.

        Until an amendment, supplement or waiver becomes effective, a consent to
it by a Holder is a continuing consent by the Holder and every subsequent Holder
of a Security or portion of a Security that evidences the same debt as the
consenting Holder's Security, even if notation of the consent is not made on any
Security. However, any such Holder or subsequent Holder may revoke the consent
as to his Security or portion of a Security if the Trustee receives the notice
of revocation before the date the amendment, supplement or waiver becomes
effective.

        After an amendment, supplement or waiver becomes effective, it shall
bind every Securityholder, unless it makes a change described in any of clauses
(a) through (h) of Section 11.2. In that case the amendment, supplement or
waiver shall bind each Holder of a Security who has consented to it and every
subsequent Holder of a Security or portion of a Security that evidences the same
debt as the consenting Holder's Security.

SECTION 11.5 NOTATION ON OR EXCHANGE OF SECURITIES.

        If an amendment, supplement or waiver changes the terms of a Security,
the Trustee may require the Holder of the Security to deliver it to the Trustee.
The Trustee may place an appropriate notation on the Security about the changed
terms and return it to the Holder. Alternatively, if the Company or the Trustee
so determines, the Company in exchange for the Security shall issue and the
Trustee shall authenticate a new Security that reflects the changed terms.

SECTION 11.6 TRUSTEE TO SIGN AMENDMENTS, ETC.

        The Trustee shall sign any amendment or supplement authorized pursuant
to this Article 11 if the amendment or supplement does not adversely affect the
rights, duties, liabilities or immunities of the Trustee. If it does, the
Trustee may but need not sign it. In signing or refusing to sign such amendment
or supplement, the Trustee shall be entitled to receive and, subject to Section
9.1 shall be fully protected in relying upon, an Opinion of Counsel stating that
such amendment or supplement is authorized or permitted by this Indenture. The
Company may not sign an amendment or supplement until the Board of Directors
approves it.

                                  ARTICLE 12.

                                  MISCELLANEOUS

SECTION 12.1 TRUST INDENTURE ACT CONTROLS.

        If any provision of this Indenture limits, qualifies or conflicts with
the duties imposed by any of Sections 310 to 317, inclusive, of the TIA through
operation of Section 318(c) thereof, upon qualification of this Indenture
thereunder such imposed duties shall control.



                                       73
<PAGE>   79


SECTION 12.2 NOTICES.

        Any notice or communication shall be given in writing and delivered in
person or mailed by first class mail, postage prepaid, addressed as follows:


                             If to the Company:

                             Incyte Pharmaceuticals, Inc.
                             3174 Porter Drive
                             Palo Alto, California 94304

                             Attention:  Chief Financial Officer


                             If to the Trustee:

                             State Street Bank and Trust
                             Company of California, N.A.
                             633 West 5th Street, 12th Floor
                             Los Angeles, CA  90071

                             Attention:  Corporate Trust Department
                                         (Incyte Pharmaceuticals, Inc.
                                         5.5% Convertible Subordinated
                                         Notes Due 2007)

        Such notices or communications shall be effective when received.

        The Company or the Trustee by notice to the other may designate
additional or different addresses for subsequent notice or communications.

        Any notice or communication mailed to a Securityholder shall be mailed
by first class mail to him at his address shown on the register kept by the
Registrar.

        Failure to mail a notice or communication to a Securityholder or any
defect in it shall not affect its sufficiency with respect to other
Securityholders. If a notice or communication to a Securityholder is mailed in
the manner provided above, it is duly given, whether or not the addressee
receives it.

SECTION 12.3 COMMUNICATIONS BY HOLDERS WITH OTHER HOLDERS.

        Securityholders may communicate pursuant to TIA 312(b) with other
Securityholders with respect to their rights under this Indenture or the
Securities. The Company, the Trustee, the Registrar and any other person shall
have the protection of TIA 312(c).

SECTION 12.4 CERTIFICATE AND OPINION AS TO CONDITIONS PRECEDENT.

        (a) Upon any request or application by the Company to the Trustee to
take any action under this Indenture, the Company shall furnish to the Trustee
at the request of the Trustee:



                                       74
<PAGE>   80

        (1) an Officers' Certificate stating that, in the opinion of the
signers, all conditions precedent (including any covenants compliance with which
constitutes a condition precedent), if any, provided for in this Indenture
relating to the proposed action have been complied with; and

        (2) an Opinion of Counsel stating that, in the opinion of such counsel,
all such conditions precedent (including any covenants compliance with which
constitutes a condition precedent) have been complied with.

        (b) Each Officers' Certificate and Opinion of Counsel with respect to
compliance with a condition or covenant provided for in this Indenture (other
than annual certificates provided pursuant to Section 6.4 hereof) shall include:

        (1) a statement that the person making such certificate or opinion has
read such covenant or condition;

        (2) a brief statement as to the nature and scope of the examination or
investigation upon which the statements or opinions contained in such
certificate or opinion are based;

        (3) a statement that, in the opinion of such person, he has made such
examination or investigation as is necessary to enable him to express an
informed opinion as to whether or not such covenant or condition has been
complied with; and

        (4) a statement as to whether or not, in the opinion of such person,
such condition or covenant has been complied with; provided, however, that with
respect to matters of fact an Opinion of Counsel may rely on Officers'
Certificates or certificates of public officials.

SECTION 12.5 RECORD DATE FOR VOTE OR CONSENT OF SECURITYHOLDERS.

        The Company (or, in the event deposits have been made pursuant to
Section 6.3 or 10.1, the Trustee) may set a record date for purposes of
determining the identity of Securityholders entitled to vote or consent to any
action by vote or consent authorized or permitted under this Indenture, which
record date shall be the later of 10 days prior to the first solicitation of
such vote or consent or the date of the most recent list of Securityholders
furnished to the Trustee pursuant to Section 2.5 hereof prior to such
solicitation. If a record date is fixed, those persons who were Holders of
Securities at such record date (or their duly designated proxies), and only
those persons, shall be entitled to take such action by vote or consent or to
revoke any vote or consent previously given, whether or not such persons
continue to be Holders after such record date.

SECTION 12.6 RULES BY TRUSTEE, PAYING AGENT, REGISTRAR.

        The Trustee may make reasonable rules for action by or at a meeting of
Holders. The Registrar or the Paying Agent may make reasonable rules for its
functions.

SECTION 12.7 LEGAL HOLIDAYS.

        A "Legal Holiday" is a Saturday, or a Sunday or a day on which state or
Federally chartered banking institutions in New York or the city and state where
the Trust Office of the



                                       75
<PAGE>   81

Trustee is located (which initially is Los Angeles, California) are not required
to be open. If a payment date is a Legal Holiday at a place of payment, payment
may be made at that place on the next succeeding day that is not a Legal
Holiday, and no interest shall accrue for the intervening period.

SECTION 12.8 GOVERNING LAW.

        The laws of the State of New York shall govern this Indenture and the
Securities without regard to principles of conflicts of law.

SECTION 12.9 NO ADVERSE INTERPRETATION OF OTHER AGREEMENTS.

        This Indenture may not be used to interpret another indenture, loan or
debt agreement of the Company or a Subsidiary. Any such indenture, loan or debt
agreement may not be used to interpret this Indenture.

SECTION 12.10 NO RECOURSE AGAINST OTHERS.

        All liability described in paragraph 18 of the Securities of any
director, officer, employee or stockholder, as such, of the Company is waived
and released.

SECTION 12.11 SUCCESSORS.

        All agreements of the Company in this Indenture and the Securities shall
bind its successor. All agreements of the Trustee in this Indenture shall bind
its successor.

SECTION 12.12 MULTIPLE COUNTERPARTS.

        The parties may sign multiple counterparts of this Indenture. Each
signed counterpart shall be deemed an original, but all of them together
represent the same agreement.

SECTION 12.13 SEPARABILITY.

        In case any provision in this Indenture or in the Securities shall be
invalid, illegal or unenforceable, the validity, legality and enforceability of
the remaining provisions shall not in any way be affected or impaired thereby.

SECTION 12.14 TABLE OF CONTENTS, HEADINGS, ETC.

        The table of contents, cross-reference sheet and headings of the
Articles and Sections of this Indenture have been inserted for convenience of
reference only, are not to be considered a part hereof, and shall in no way
modify or restrict any of the terms or provisions hereof.



                                       76
<PAGE>   82










                                       77
<PAGE>   83

        IN WITNESS WHEREOF, the parties hereto have hereunto set their hands as
of the 4th day of February, 2000.

                                       INCYTE PHARMACEUTICALS, INC.


                                       By:  /s/ John M. Vuko
                                          ---------------------------------
                                       Title:  Chief Financial Officer


                                       STATE STREET BANK AND TRUST
                                       COMPANY OF CALIFORNIA, N.A., as Trustee


                                       By:  /s/ Scott C. Emmons
                                          ---------------------------------
                                       Title:  Vice President



                                       78
<PAGE>   84

                                                                       EXHIBIT A


                                FORM OF SECURITY
(Certificated Note - Rule 144A Global Note - Regulation S Permanent Global Note)

Number ______                                                  CUSIP [45337CAA0]
                                                                CINS [U45236AA1]

                              [GLOBAL NOTE LEGEND:

UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION ("DTC"), TO INCYTE
PHARMACEUTICALS, INC. OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE, OR
PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR
IN SUCH OTHER NAME AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC (AND
ANY PAYMENT IS MADE TO CEDE & CO. OR TO SUCH OTHER ENTITY AS IS REQUESTED BY AN
AUTHORIZED REPRESENTATIVE OF DTC), ANY TRANSFER, PLEDGE, OR OTHER USE HEREOF FOR
VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL INASMUCH AS THE REGISTERED
OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.

TRANSFERS OF THIS GLOBAL NOTE SHALL BE LIMITED TO TRANSFER IN WHOLE, BUT NOT IN
PART, TO NOMINEES OF DTC OR TO A SUCCESSOR THEREOF OR SUCH SUCCESSOR'S NOMINEE
AND TRANSFERS MADE IN ACCORDANCE WITH THE RESTRICTIONS SET FORTH IN THE
INDENTURE REFERRED TO ON THE REVERSE HEREOF.]

                   [GLOBAL NOTE RESTRICTED SECURITIES LEGEND:

THIS SECURITY HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED (THE "SECURITIES ACT"). THE HOLDER HEREOF, BY PURCHASING THIS SECURITY,
AGREES FOR THE BENEFIT OF THE COMPANY THAT THIS SECURITY MAY NOT BE RESOLD,
PLEDGED OR OTHERWISE TRANSFERRED (X) PRIOR TO THE EXPIRATION OF THE HOLDING
PERIOD UNDER RULE 144(k) (OR ANY SUCCESSOR THERETO) UNDER THE SECURITIES ACT
WHICH IS APPLICABLE TO THIS SECURITY OR (Y) BY ANY HOLDER THAT WAS AN
"AFFILIATE" (WITHIN THE MEANING OF RULE 144 UNDER THE SECURITIES ACT) OF THE
COMPANY AT ANY TIME DURING THE THREE MONTHS PRECEDING THE DATE OF SUCH TRANSFER,
IN EITHER CASE, OTHER THAN (1) TO THE COMPANY, (2) SO LONG AS THIS SECURITY IS
ELIGIBLE FOR RESALE PURSUANT TO RULE 144A UNDER THE SECURITIES ACT ("RULE
144A"), TO A PERSON WHOM THE SELLER REASONABLY BELIEVES IS A QUALIFIED
INSTITUTIONAL BUYER WITHIN THE MEANING OF RULE 144A, PURCHASING FOR ITS OWN
ACCOUNT OR FOR THE ACCOUNT OF A QUALIFIED INSTITUTIONAL BUYER TO WHOM NOTICE IS
GIVEN



                                      A-1
<PAGE>   85
THAT THE RESALE, PLEDGE OR OTHER TRANSFER IS BEING MADE IN RELIANCE ON RULE
144A, (3) IN AN OFFSHORE TRANSACTION (AS DEFINED IN REGULATION S UNDER THE
SECURITIES ACT) IN ACCORDANCE WITH REGULATION S UNDER THE SECURITIES ACT, (4) TO
AN INSTITUTION THAT IS AN "ACCREDITED INVESTOR" AS DEFINED IN RULE 501(a)(1),
(2), (3) OR (7) UNDER THE SECURITIES ACT ("INSTITUTIONAL ACCREDITED INVESTOR")
THAT IS ACQUIRING THIS SECURITY FOR INVESTMENT PURPOSES AND NOT FOR
DISTRIBUTION, AND THAT, PRIOR TO SUCH TRANSFER, DELIVERS TO THE COMPANY AND THE
TRUSTEE A SIGNED LETTER CONTAINING CERTAIN REPRESENTATIONS AND AGREEMENTS
RELATING TO THE RESTRICTIONS ON TRANSFER OF THE SECURITY EVIDENCED HEREBY (THE
FORM OF WHICH LETTER MAY BE OBTAINED FROM THE TRUSTEE), (5) PURSUANT TO AN
EXEMPTION FROM REGISTRATION UNDER THE SECURITIES ACT PROVIDED BY RULE 144 (IF
APPLICABLE) UNDER THE SECURITIES ACT OR (6) PURSUANT TO AN EFFECTIVE
REGISTRATION STATEMENT UNDER THE SECURITIES ACT, IN EACH CASE IN ACCORDANCE WITH
ANY APPLICABLE SECURITIES LAWS OF ANY STATE OF THE UNITED STATES. THE HOLDER
HEREOF, BY PURCHASING THIS SECURITY, REPRESENTS AND AGREES FOR THE BENEFIT OF
THE COMPANY THAT IT IS (1) A QUALIFIED INSTITUTIONAL BUYER OR (2) AN
INSTITUTIONAL ACCREDITED INVESTOR AND THAT IT IS HOLDING THIS SECURITY FOR
INVESTMENT PURPOSES AND NOT FOR DISTRIBUTION OR (3) NOT A U.S. PERSON AND IS
OUTSIDE THE UNITED STATES WITHIN THE MEANING OF (OR AN ACCOUNT SATISFYING THE
REQUIREMENTS OF PARAGRAPH (k)(2) OF RULE 902 UNDER) REGULATION S UNDER THE
SECURITIES ACT. IN ANY CASE THE HOLDER HEREOF WILL NOT, DIRECTLY OR INDIRECTLY,
ENGAGE IN ANY HEDGING TRANSACTION WITH REGARD TO THIS SECURITY OR ANY COMMON
STOCK ISSUABLE UPON CONVERSION OF THIS SECURITY EXCEPT AS PERMITTED BY THE
SECURITIES ACT

                [CERTIFICATED NOTE RESTRICTED SECURITIES LEGEND:

THIS SECURITY HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED (THE "SECURITIES ACT"). THE HOLDER HEREOF, BY PURCHASING THIS SECURITY,
AGREES FOR THE BENEFIT OF THE COMPANY THAT THIS SECURITY MAY NOT BE RESOLD,
PLEDGED OR OTHERWISE TRANSFERRED (X) PRIOR TO THE EXPIRATION OF THE HOLDING
PERIOD UNDER RULE 144(k) (OR ANY SUCCESSOR THERETO) UNDER THE SECURITIES ACT
WHICH IS APPLICABLE TO THIS SECURITY OR (Y) BY ANY HOLDER THAT WAS AN
"AFFILIATE" (WITHIN THE MEANING OF RULE 144 UNDER THE SECURITIES ACT) OF THE
COMPANY AT ANY TIME DURING THE THREE MONTHS PRECEDING THE DATE OF SUCH TRANSFER,
IN EITHER CASE, OTHER THAN (1) TO THE COMPANY, (2) SO LONG AS THIS SECURITY IS
ELIGIBLE FOR RESALE PURSUANT TO RULE 144A UNDER THE SECURITIES ACT ("RULE
144A"), TO A PERSON WHOM THE SELLER REASONABLY BELIEVES IS A QUALIFIED
INSTITUTIONAL BUYER WITHIN THE MEANING OF RULE 144A, PURCHASING FOR ITS OWN
ACCOUNT OR FOR THE ACCOUNT OF A QUALIFIED INSTITUTIONAL BUYER TO WHOM NOTICE IS
GIVEN



                                      A-2
<PAGE>   86
THAT THE RESALE, PLEDGE OR OTHER TRANSFER IS BEING MADE IN RELIANCE ON RULE 144A
(AS INDICTED BY THE BOX CHECKED BY THE TRANSFEROR ON THE CERTIFICATE OF TRANSFER
ON THE REVERSE OF THIS SECURITY), (3) IN AN OFFSHORE TRANSACTION (AS DEFINED IN
REGULATION S UNDER THE SECURITIES ACT) IN ACCORDANCE WITH REGULATION S UNDER THE
SECURITIES ACT (AS INDICATED BY THE BOX CHECKED BY THE TRANSFEROR ON THE
CERTIFICATE OF TRANSFER ON THE REVERSE OF THIS SECURITY), (4) TO AN INSTITUTION
THAT IS AN "ACCREDITED INVESTOR" AS DEFINED IN RULE 501(a)(1) (2), (3) or (7)
UNDER THE SECURITIES ACT ("INSTITUTIONAL ACCREDITED INVESTOR") (AS INDICATED BY
THE BOX CHECKED BY THE TRANSFEROR ON THE CERTIFICATE OF TRANSFER ON THE REVERSE
OF THIS SECURITY) THAT IS ACQUIRING THIS SECURITY FOR INVESTMENT PURPOSES AND
NOT FOR DISTRIBUTION, AND THAT, PRIOR TO SUCH TRANSFER, DELIVERS TO THE COMPANY
AND THE TRUSTEE A SIGNED LETTER CONTAINING CERTAIN REPRESENTATIONS AND
AGREEMENTS RELATING TO THE RESTRICTIONS ON TRANSFER OF THE SECURITY EVIDENCED
HEREBY (THE FORM OF WHICH LETTER MAY BE OBTAINED FROM THE TRUSTEE), (5) PURSUANT
TO AN EXEMPTION FROM REGISTRATION UNDER THE SECURITIES ACT PROVIDED BY RULE 144
(IF APPLICABLE) UNDER THE SECURITIES ACT (AS INDICATED BY THE BOX CHECKED BY THE
TRANSFEROR ON THE CERTIFICATE OF TRANSFER ON THE REVERSE OF THIS SECURITY) OR
(6) PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT, IN
EACH CASE ACCORDANCE WITH ANY APPLICABLE SECURITIES LAWS OF ANY STATE OF THE
UNITED STATES. PRIOR TO A TRANSFER OF THIS SECURITY (OTHER THAN A TRANSFER
PURSUANT TO CLAUSE (6) ABOVE), THE HOLDER OF THIS SECURITY MUST, PRIOR TO SUCH
TRANSFER, FURNISH TO THE COMPANY AND THE TRUSTEE SUCH CERTIFICATES AND OTHER
INFORMATION AND, IN THE CASE OF A TRANSFER PURSUANT TO CLAUSE (5) ABOVE, A LEGAL
OPINION AS THEY MAY REASONABLY REQUIRE TO CONFIRM THAT ANY TRANSFER BY IT OF
THIS SECURITY COMPLIES WITH THE FOREGOING RESTRICTIONS. THE HOLDER HEREOF, BY
PURCHASING THIS SECURITY, REPRESENTS AND AGREES FOR THE BENEFIT OF THE COMPANY
THAT IT IS (1) A QUALIFIED INSTITUTIONAL BUYER OR (2) AN INSTITUTIONAL
ACCREDITED INVESTOR AND THAT HOLDING THIS SECURITY FOR INVESTMENT PURPOSES AND
NOT FOR DISTRIBUTION OR (3) NOT A U.S. PERSON AND IS OUTSIDE THE UNITED STATES
WITHIN THE MEANING OF (OR AN ACCOUNT SATISFYING THE REQUIREMENTS OF PARAGRAPH
(k)(2) OF RULE 902) UNDER REGULATION S UNDER THE SECURITIES ACT. IN ANY CASE THE
HOLDER HEREOF WILL NOT, DIRECTLY OR INDIRECTLY, ENGAGE IN ANY HEDGING
TRANSACTION WITH REGARD TO THIS SECURITY OR ANY COMMON STOCK ISSUABLE UPON
CONVERSION OF THIS SECURITY EXCEPT AS PERMITTED BY THE SECURITIES ACT



                                      A-3
<PAGE>   87

                           [FORM OF FACE OF SECURITY]

                          INCYTE PHARMACEUTICALS, INC.

                   5.5% Convertible Subordinated Note Due 2007

        Incyte Pharmaceuticals, Inc., a Delaware corporation, promises to pay to
__________________ or registered assigns, the principal sum of
________________________ Dollars ($__________) on February 1, 2007 and to pay
interest on the principal amount of this Note beginning February 4, 2000 at the
rate of 5.5% per annum.

Interest Payment Dates:      February 1 and August 1
Record Dates:                January 15 and July 15

        This Note is convertible at such times and as specified on the other
side of this Note. Additional provisions of this Note are set forth on the other
side of this Note.

Dated:  February 4, 2000               INCYTE PHARMACEUTICALS, INC.

                                       By:
                                          ---------------------------------
                                          Name:
                                          Title:

[SEAL]

Attest:

-----------------------------------
Name:
Title:

Trustee's Certificate of
Authentication:

This is one of the Securities
referred to in the within mentioned
Indenture.

STATE STREET BANK AND TRUST COMPANY OF CALIFORNIA, N.A., as Trustee
By:
   -----------------------------------
         Authorized Signatory



                                      A-4
<PAGE>   88



                       [FORM OF REVERSE SIDE OF SECURITY]

                          INCYTE PHARMACEUTICALS, INC.

                   5.5% Convertible Subordinated Note Due 2007

1.      Interest.

        Incyte Pharmaceuticals, Inc., a Delaware corporation (the "Company"),
promises to pay interest on the principal amount of this Note at the rate per
annum shown above. The Company shall pay interest semi-annually on February 1
and August 1 of each year, commencing August 1, 2000. Interest on the Notes will
accrue from the most recent date to which interest has been paid or, if no
interest has been paid, from February 4, 2000. Interest will be computed on the
basis of a 360-day year of twelve 30-day months.

        The Holder of this Note is entitled to the benefits of the Registration
Rights Agreement, dated February 4, 2000, among the Company, Deutsche Bank
Securities Inc. and Warburg Dillon Read LLC.

2.      Method of Payment.

        The Company will pay interest on this Note (except defaulted interest)
to the person who is the registered Holder of this Note at the close of business
on the January 15 and July 15 next preceding the interest payment date. The
Holder must surrender this Note to the Paying Agent to collect payment of
principal. The Company will pay principal and interest in money of the United
States that at the time of payment is legal tender for payment of public and
private debts. The Company, however, may pay principal and interest by its check
payable in such money. It may mail an interest check to the Holder's registered
address.

3.      Paying Agent, Registrar and Conversion Agent.

        Initially, State Street Bank and Trust Company of California, N.A. (the
"Trustee") will act as Paying Agent, Registrar and Conversion Agent. The Company
may change any Paying Agent, Registrar or Conversion Agent without notice to the
holder. The Company or any of its Subsidiaries may act as Paying Agent,
Registrar or Conversion Agent.

4.      Indenture; Limitations.

        This Note is one of a duly authorized issue of Notes of the Company
designated as its 5.5% Convertible Subordinated Notes Due 2007 (the "Notes"),
issued under an Indenture dated as of February 4, 2000 (the "Indenture"),
between the Company and the Trustee. The terms of this Note include those stated
in the Indenture and those made part of the Indenture by reference to the Trust
Indenture Act of 1939 (15 U.S.C. 77aaa-77bbbb), as amended by the Trust
Indenture Reform Act of 1990, as in effect on the date hereof or, from and after
the date that the Indenture shall be qualified thereunder, as in effect on such
date. This Note is subject to all such terms, and the holder of this Note is
referred to the Indenture and said Act for a statement of them.



                                      A-5
<PAGE>   89

        The Notes are subordinated unsecured obligations of the Company limited
to up to $150,000,000 aggregate principal amount plus an additional principal
amount not exceeding $50,000,000 in the aggregate as may be issued upon the
exercise by the Initial Purchasers, in whole or in part, of the Purchase Option.

5.      Provisional Redemption.

        The Notes may be provisionally redeemed by the Company, in whole or in
part, at any time prior to February 7, 2003, at a Redemption Price equal to
$1,000 per Security to be redeemed plus accrued and unpaid interest, if any
(including Additional Interest, if any) to the Redemption Date if (i) the
closing price of the Common Stock shall have exceeded 150% of the conversion
price then in effect for at least 20 Trading Days in any consecutive 30-Trading
Day period ending on the Trading Day prior to the date of mailing of the notice
of Provisional Redemption, which date shall be no more than 60 nor less than 20
days prior to the Redemption Date and (ii) the Shelf Registration Statement is
effective and available for use and is expected to remain effective and
available for use for the 30 days immediately following the Redemption Date.
Upon any such Provisional Redemption, the Company shall make an additional
Make-Whole Payment in cash with respect to the Securities called for redemption
to Holders on the date of mailing of the notice of Provisional Redemption in an
amount equal to $165 per $1,000 Security, less the amount of any interest
actually paid on such Security prior to such date. The Company shall make the
Make-Whole Payment on all Securities called for Provisional Redemption,
including any Securities converted after the date of mailing of the notice of
Provisional Redemption and prior to the Redemption Date.

6.      Optional Redemption.

        The Notes may be redeemed at the Company's option, in whole or in part,
at any time and from time to time on and after February 7, 2003. The redemption
price for the Notes, expressed as a percentage of the principal amount, is 102.2
% if the Notes are redeemed in the period beginning February 7, 2003 and ending
February 1, 2004, and is as follows for the 12-month periods beginning February
1 as follows:

<TABLE>
<CAPTION>
               Year                                    Percentage
               ----                                    ----------
<S>                                                    <C>
               2004                                    101.1%
               2005 and thereafter                     100.0%
</TABLE>

together in the case of any such redemption with accrued interest to the date of
redemption, but any interest payment that is due and payable on or prior to such
date of redemption will be payable to the Holders of such Notes, or one or more
predecessor Notes, of record at the close of business on the relevant record
dates referred to on the face hereof, all as provided in the Indenture.

7.      Notice of Redemption.

        Notice of redemption will be mailed by first class mail at least 20 days
but not more than 60 days before the redemption date to each Holder of Notes to
be redeemed at his registered address. Notes in denominations larger than $1,000
may be redeemed in part, but only in whole



                                      A-6
<PAGE>   90

multiples of $1,000. On and after the redemption date, subject to the deposit
with the Paying Agent of funds sufficient to pay the redemption price, interest
ceases to accrue on Notes or portions of them called for redemption.

8.      Repurchase of Notes at Option of Holder upon a Change in Control.

        If at any time that Notes remain outstanding there shall have occurred a
Change in Control (as defined in the Indenture), at the option of the Holder and
subject to the terms and conditions of the Indenture, the Company shall become
obligated to repurchase all or any part specified by the Holder (so long as the
principal amount of such part is $1,000 or an integral multiple thereof) of the
Notes held by such Holder on the Repurchase Date. The Holder shall have the
right to withdraw any Repurchase Notice by delivering a written notice of
withdrawal to the Paying Agent in accordance with the terms of the Indenture.
The Repurchase Price is payable in cash or, at the Company's option but subject
to the satisfaction of certain conditions set forth in the Indenture, in shares
of Common Stock valued at 95% of the average Closing Prices of the Common Stock
for the five Trading Days preceding and including the third Trading Day prior to
the Repurchase Date.

9.      Conversion.

        At any time after 90 days following the latest date of original issuance
of the Notes and prior to the close of business on February 1, 2007, a Holder of
a Note may convert such Note into shares of Common Stock of the Company;
provided, however, that if the Note is called for redemption, the conversion
right will terminate at the close of business on the third business day before
the redemption date of such Note (unless the Company shall default in making the
redemption payment when due, in which case the conversion right shall terminate
at the close of business on the date such default is cured and such Note is
redeemed). The initial conversion price is $134.839 per share, subject to
adjustment under certain circumstances as described in the Indenture. The number
of shares issuable upon conversion of a Note is determined by dividing the
principal amount converted by the conversion price in effect on the conversion
date. Upon conversion, no adjustment for interest or dividends will be made. No
fractional shares will be issued upon conversion; in lieu thereof, an amount
will be paid in cash based upon the current market price (as defined in the
Indenture) of the Common Stock on the last trading day prior to the date of
conversion.

        To convert a Note, a Holder must (a) complete and sign the conversion
notice set forth below and deliver such notice to the Conversion Agent, (b)
surrender the Note to the Conversion Agent, (c) furnish appropriate endorsements
or transfer documents if required by the Registrar or the Conversion Agent and
(d) pay any transfer or similar tax, if required. If a Holder surrenders a Note
for conversion between the record date for the payment of an installment of
interest and the next interest payment date, the Note must be accompanied by
payment of an amount equal to the interest payable on such interest payment date
on the principal amount of the Note or portion thereof then converted; provided,
however, that no such payment shall be required if such Note has been called for
redemption between such record date and the date five business days after such
interest payment date, or if such Note is surrendered for conversion on the
interest payment date. A Holder may convert a portion of a Note equal to $1,000
or any integral multiple thereof.



                                      A-7
<PAGE>   91

        A Note in respect of which a Holder had delivered a Repurchase Notice
exercising the option of such Holder to require the Company to repurchase such
Note may be converted only if the notice of exercise is withdrawn as provided
above and in accordance with the terms of the Indenture.

10.     Subordination.

        The indebtedness evidenced by the Notes is, to the extent and in the
manner provided in the Indenture, subordinate and junior in right of payment to
the prior payment in full of all Senior Indebtedness of the Company, as defined
in the Indenture. Any Holder by accepting this Note agrees to and shall be bound
by such subordination provisions and authorizes the Trustee to give them effect.

        In addition to all other rights of Senior Indebtedness described in the
Indenture, the Senior Indebtedness shall continue to be Senior Indebtedness and
entitled to the benefits of the subordination provisions irrespective of any
amendment, modification or waiver of any terms of any instrument relating to the
Senior Indebtedness or any extension or renewal of the Senior Indebtedness.

11.     Denominations, Transfer, Exchange.

        The Notes are in registered form without coupons in denominations of
$1,000 and integral multiples thereof. A Holder may register the transfer of or
exchange Notes in accordance with the Indenture. The Registrar may require a
Holder, among other things, to furnish appropriate endorsements and transfer
documents and to pay any taxes or other governmental charges that may be imposed
by law or permitted by the Indenture.

        [Global Note Insert:

        The aggregate principal amount of the Note in global form represented
        hereby may from time to time be reduced or increased to reflect
        exchanges of a part of this Note in global form for definitive Notes or
        exchanges of definitive Notes for a part of this Note in global form or
        conversions or redemptions of a part of this Note in global form or
        cancellations of a part of this Note in global form or transfers of
        definitive Notes in return for a part of this Note in global form or
        transfers of a part of this Note in global form effected by delivery of
        definitive Notes, in each case, and in any such case, by means of
        notations on the Schedule of Exchanges, Conversions, Redemptions,
        Cancellations and Transfers on the last page hereof. Notwithstanding any
        provision of this Note to the contrary, (i) exchanges of a part of this
        Note in global form for definitive Notes, (ii) exchanges of definitive
        Notes for a part of this Note in global form, (iii) conversions or
        redemptions of a part of this Note in global form, (iv) cancellations of
        a part of this Note in global form, (v) transfers of definitive Notes in
        return for a part of this Note in global form and (vi) transfers of a
        part of this Note in global form effected by delivery of definitive
        Notes may be effected without the surrendering of this Note in global
        form, provided that appropriate notations on the Schedule of Exchanges,
        Conversions, Redemptions, Cancellations and Transfers are made by the
        Trustee, or the Custodian at the direction of the Trustee, to



                                      A-8
<PAGE>   92

        reflect the appropriate reduction or increase, as the case may be, in
        the aggregate principal amount of this Note in a global form resulting
        therefrom or as a consequence thereof.]

12.     Persons Deemed Owners.

        The registered holder of a Note may be treated as the owner of it for
all purposes.

13.     Unclaimed Money.

        If money for the payment of principal or interest remains unclaimed for
two years, the Trustee or Paying Agent will pay the money back to the Company at
its request. After that, Holders entitled to money must look to the Company for
payment unless an abandoned property law designates another person.

14.     Amendment, Supplement, Waiver.

        Subject to certain exceptions, the Indenture or the Notes may be amended
or supplemented with the consent of the Holders of a majority in principal
amount of the Notes then outstanding and any past default or compliance with any
provision may be waived in a particular instance with the consent of the Holders
of a majority in principal amount of the Notes then outstanding. Without the
consent of or notice to any Holder, the Company and the Trustee may amend or
supplement the Indenture or the Notes to, among other things, provide for
uncertificated Notes in addition to or in place of certificated Notes, or to
cure any ambiguity, omission, defect or inconsistency or make any other change
that does not adversely affect the rights of any Holder.

15.     Successor Corporation.

        When a successor corporation assumes all the obligations of its
predecessor under the Notes and the Indenture, the predecessor corporation will
be released from those obligations.

16.     Defaults and Remedies.

        An Event of Default is: default for 30 days in payment of interest on
the Notes; default in payment of principal on the Notes when due; failure by the
Company for 60 days after notice to it to comply with any of its other
agreements contained in the Indenture or the Notes; default by the Company or
any Subsidiary with respect to its obligation to pay principal of or interest on
indebtedness for borrowed money aggregating more than $10 million or the
acceleration of such indebtedness if not withdrawn within 10 days from the date
of such acceleration; and certain events of bankruptcy, insolvency or
reorganization of the Company or any of its subsidiaries. If an Event of Default
(other than as a result of certain events of bankruptcy, insolvency or
reorganization) occurs and is continuing, the Trustee or the Holders of at least
25% in principal amount of the Notes then outstanding may declare all unpaid
principal of and accrued interest to the date of acceleration on the Notes then
outstanding to be due and payable immediately, all as and to the extent provided
in the Indenture. If an Event of Default occurs as a result of certain events of
bankruptcy, insolvency or reorganization, all unpaid principal of and accrued
interest on the Notes then outstanding shall become due and payable immediately
without any



                                      A-9
<PAGE>   93
declaration or other act on the part of the Trustee or any Holder, all as and to
the extent provided in the Indenture. Holders may not enforce the Indenture or
the Notes except as provided in the Indenture. The Trustee may require indemnity
satisfactory to it before it enforces the Indenture or the Notes. Subject to
certain limitations, Holders of a majority in principal amount of the Notes then
outstanding may direct the Trustee in its exercise of any trust or power. The
Trustee may withhold from Holders notice of any continuing default (except a
default in payment of principal or interest) if it determines that withholding
notice is in their interests. The Company is required to file periodic reports
with the Trustee as to the absence of default.

17.     Trustee Dealings with the Company.

        State Street Bank and Trust Company of California, N.A., the Trustee
under the Indenture, in its individual or any other capacity, may make loans to,
accept deposits from, and perform services for the Company or an Affiliate of
the Company, and may otherwise deal with the Company or an Affiliate of the
Company, as if it were not the Trustee.

18.     No Recourse Against Others.

        A director, officer, employee or stockholder, as such, of the Company
shall not have any liability for any obligations of the Company under the Notes
or the Indenture or for any claim based on, in respect or by reason of, such
obligations or their creation. The Holder of this Note by accepting this Note
waives and releases all such liability. The waiver and release are part of the
consideration for the issue of this Note.

19.     Discharge Prior to Maturity.

        If the Company deposits with the Trustee or the Paying Agent money or
U.S. Government Obligations sufficient to pay the principal of and interest on
the Notes to maturity as provided in the Indenture, the Company will be
discharged from the Indenture except for certain Sections thereof.

20.     Authentication.

        This Note shall not be valid until the Trustee or an authenticating
agent signs the certificate of authentication on the other side of this Note.

21.     Abbreviations and Definitions.

        Customary abbreviations may be used in the name of a Holder or an
assignee, such as: TEN COM (= tenants in common), TEN ENT (= tenants by the
entireties), JT TEN (= joint tenants with right of survivorship and not as
tenants in common), CUST (= Custodian) and U/G/M/A (= Uniform Gifts to Minors
Act).

        All capitalized terms used in this Note and not specifically defined
herein are defined in the Indenture and are used herein as so defined.



                                      A-10
<PAGE>   94

22.     Indenture to Control.

        In the case of any conflict between the provisions of this Note and the
Indenture, the provisions of the Indenture shall control.

        The Company will furnish to any Holder, upon written request and without
charge, a copy of the Indenture. Requests may be made to: Incyte
Pharmaceuticals, Inc., 3174 Porter Drive, Palo Alto, California 94304,
Attention: Chief Financial Officer.



                                      A-11
<PAGE>   95

                                 TRANSFER NOTICE

This Transfer Notice Relates to $__________ principal amount of the 5.5%
Convertible Subordinated Notes Due 2007 of Incyte Pharmaceuticals, Inc., a
Delaware corporation, held by ______________________________ (the "Transferor").

            (I) or (we) assign and transfer this Convertible Note to

--------------------------------------------------------------------------------
              (Print or type assignee's name, address and zip code)

--------------------------------------------------------------------------------

--------------------------------------------------------------------------------
               (Insert assignee's social security or tax I.D. no.)

and irrevocably appoint _______________________________ agent to transfer this
Note on the books of the Company. The agent may substitute another to act for
him.

         Your Signature:
                        --------------------------------------------------------
 (Sign exactly as your name appears on the other side of this Convertible Note)

         Date:
              ------------------------------------------------------------------

         Signature Guarantee:(1)
                                ------------------------------------------------

In connection with any transfer of any of the Notes evidenced by this
certificate occurring prior to the date that is three years after the later of
the date of original issuance of such Notes and the last date, if any, on which
such Notes were owned by the Company or any Affiliate of the Company, the
undersigned confirms that such Notes are being transferred:

CHECK ONE BOX BELOW

        (1) [ ] to Incyte Pharmaceuticals, Inc.; or

        (2) [ ] pursuant to and in compliance with Rule 144A under the
Securities Act of 1933, as amended; or

        (3) [ ] pursuant to and in compliance with Regulation S under the
Securities Act of 1933, as amended; or

        (4) [ ] to an institutional "accredited investor" (as defined in Rule
501(a)(1), (2), (3) or (7) under the Securities Act of 1933, as amended, that
has furnished to the Trustee a signed letter containing certain representations
and agreements (the form of which letter can be obtained from the Trustee); or

--------------
(1) Signature must be guaranteed by a commercial bank, trust company or member
    firm of the New York Stock Exchange.


                                      A-12
<PAGE>   96
        (5) [ ] pursuant to another available exemption from the registration
requirements of the Securities Act of 1933; or

         (6) [ ] pursuant to an effective registration statement under the
Securities Act of 1933.

                  Unless one of the boxes is checked, the Trustee will refuse to
                  register any of the Notes evidenced by this certificate in the
                  name of any person other than the registered holder thereof;
                  provided, however, that if box (2), (3), (4) or (5) is
                  checked, the Trustee may require, prior to registering any
                  such transfer of the Notes such legal opinions, certifications
                  and other information as the Company has reasonably requested
                  to confirm that such transfer is being made pursuant to an
                  exemption from, or in a transaction not subject to, the
                  registration requirements of the Securities Act of 1933, such
                  as the exemption provided by Rule 144 under such Act.

                  Unless the box below is checked, the undersigned confirms that
                  such Note is not being transferred to an "affiliate" of the
                  Company as defined in Rule 144 under the Securities Act of
                  1933, as amended (an "Affiliate"):

        7. [ ] The transferee is an Affiliate of the Company.

                                       ------------------------------------
                                       Signature

                                       ------------------------------------
                                       Date

                                       ------------------------------------
                                       Signature Guarantee(1)


              TO BE COMPLETED BY PURCHASER IF (2) ABOVE IS CHECKED.

-----------------

(1) Signature must be guaranteed by a commercial bank, trust company or member
    firm of the New York Stock Exchange.

                                      A-13
<PAGE>   97

        The undersigned represents and warrants that it is purchasing this Note
for its own account or an account with respect to which it exercises sole
investment discretion and that it and any such account is a "qualified
institutional buyer" within the meaning of Rule 144A under the Securities Act of
1933, and is aware that the sale to it is being made in reliance on Rule 144A
and acknowledges that it has received such information regarding the Company as
the undersigned has requested pursuant to Rule 144A or has determined not to
request such information and that it is aware that the transferor is relying
upon the undersigned's foregoing representations in order to claim the exemption
from registration provided by Rule 144A.

Dated:
      ------------------------------   ------------------------------------
                                       [Signature of executive officer of
                                       purchaser]

                                       Name:
                                            -------------------------------

                                       Title:
                                             ------------------------------



                                      A-14
<PAGE>   98
                                CONVERSION NOTICE

To Incyte Pharmaceuticals, Inc.:

        The undersigned owner of this Note hereby irrevocably exercises the
option to convert this Note, or the portion below designated, into Common Stock
of Incyte Pharmaceuticals, Inc. in accordance with the terms of the Indenture
referred to in this Note, and directs that the shares issuable and deliverable
upon conversion, together with any check in payment for fractional shares, be
issued in the name of and delivered to the undersigned, unless a different name
has been indicated in the assignment below. If shares are to be issued in the
name of a person other than the undersigned, the undersigned will pay all
transfer taxes payable with respect thereto.

        Any holder of Notes, upon exercise of its conversion rights in
accordance with the terms of the Indenture and the Security, agrees to be bound
by the terms of the Registration Rights Agreement relating to the Common Stock
issuable upon conversion of the Notes.

[ ] Convert whole                      [ ]  Convert in part
                                            Amount of Note to be
                                            converted ($1,000 or integral
                                            multiples thereof):
                                            $
                                            -----------------

                                       ------------------------------------
                                       Signature (sign exactly as name
                                       appears on the other side of this Note)

                                       ------------------------------------
                                       Signature Guarantee:(1)

-----------------

(1) Signature must be guaranteed by a commercial bank, trust company or member
    firm of the New York Stock Exchange.

                                      A-15
<PAGE>   99

If you want the stock certificate made out in another person's name, complete
the following for such person:

-------------------------------------------------
Name

-------------------------------------------------
Social Security or Taxpayer Identification Number

-------------------------------------------------
Street Address

-------------------------------------------------
City, State and Zip Code



                                      A-16
<PAGE>   100
                      OPTION OF HOLDER TO ELECT REPURCHASE

        If you want to elect to have this Note repurchased by the Company
pursuant to Section 3.10 of the Indenture, check the box:

                                       [ ]

        If you want to elect to have only part of this Note repurchased by the
Company pursuant to Section 3.10 of the Indenture, state the principal amount
(which shall be $1,000 or a multiple thereof) to be repurchased:
$____________________

Dated:
-----------------------------------     -----------------------------------
                                        Signature (sign exactly as name
                                        appears on the other side of this Note)

-----------------------------------
Signature Guarantee:(1)

-----------------

(1) Signature must be guaranteed by a commercial bank, trust company or member
    firm of the New York Stock Exchange.



                                      A-17
<PAGE>   101

                            [Schedule A to Exhibit A

                          GLOBAL NOTE TRANSFER SCHEDULE

                 Changes to Principal Amount of Global Security

<TABLE>
<CAPTION>
               Principal Amount of Securities by
              which this Global Security Is to Be   Remaining Principal Amount of this     Authorized Signature
               Reduced or Increased, and Reason               Global Security             of officer of Trustee
   Date           for Reduction or Increase          (following increase or decrease)       or Note Custodian
---------     --------------------------------      ----------------------------------    ---------------------
<S>           <C>                                   <C>                                   <C>




</TABLE>

Schedule to be maintained by Depositary in cooperation with Trustee.]



                                      A-18
<PAGE>   102
                                                                     EXHIBIT B-1

         FORM OF PURCHASER LETTER FOR INSTITUTIONAL ACCREDITED INVESTORS

Incyte Pharmaceuticals, Inc.
3174 Porter Drive
Palo Alto, California  94304

State Street Bank and Trust Company of California, N.A.
633 West 5th Street, 12th Floor
Los Angeles, CA  90071
Attn:   Corporate Trust Department
        (Incyte Pharmaceuticals, Inc. 5.5%
        Convertible Subordinated Notes Due 2007)

        Re:  Incyte Pharmaceuticals, Inc. 5.5% Convertible Subordinated Notes
             Due 2007

Dear Ladies and Gentlemen:

        We are delivering this letter in connection with an offering of one or
more of the 5.5% Convertible Subordinated Notes Due 2007 (the "Notes"), which
are convertible into shares of Common Stock, par value $.001 per share, of
Incyte Pharmaceuticals, Inc. (the "Company"), all as described in the Offering
Memorandum relating to the Offering.

        We hereby confirm that:

                  (i) we are an "accredited investor" within the meaning of Rule
        501(a) (1), (2), (3) or (7) under the Securities Act of 1933 (the
        "Securities Act") or an entity in which all of the equity owners are
        accredited investors within the meaning of Rule 501(a) (1), (2), (3) or
        (7) under the Securities Act (an "Institutional Accredited Investor");

                  (ii) (A) any purchase of Notes by us will be for our own
        account or for the account of one or more other Institutional Accredited
        Investors or as fiduciary for the account of one or more trusts, each of
        which is an "accredited investor" within the meaning of Rule 501(a)(7)
        under the Securities Act and for each of which the undersigned exercises
        sole investment discretion or (B) we are a "bank," within the meaning of
        Section 3(a)(2) of the Securities Act, or a "savings and loan
        association" or other institution described in Section 3(a)(5)(A) of the
        Securities Act that is acquiring Notes as fiduciary for the account of
        one or more institutions for which we exercise sole investment
        discretion;

                  (iii) in the event that we purchase any Notes, we will acquire
        Notes having a minimum principal amount of not less than $250,000 for
        our own account or for any separate account for which we are acting;



                                      B1-1
<PAGE>   103

                  (iv) we have such knowledge and experience in financial and
        business matters that we are capable of evaluating the merits and risks
        of purchasing Notes;

                  (v) we are not acquiring Notes with a view to distribute or
        with any present intention of offering or selling Notes or the Common
        Stock issuable upon conversion thereof, except as permitted below;
        provided that the disposition of our property and property of any
        accounts for which we are acting as fiduciary shall remain at all times
        within its control; and

                  (vii) we have received a copy of the Offering Memorandum and
        acknowledge that we have had access to such financial and other
        information, and have been afforded the opportunity to access such
        financial and other information, and have been afforded the opportunity
        to ask such questions of representatives of the Company and receive
        answers thereto, as we deem necessary in connection with our decision to
        purchase Notes.

             We understand that the Notes are being offered in a transaction not
involving any public offering within the United States within the meaning of the
Securities Act and that the Notes and the shares of Common Stock issuable upon
conversion thereof (collectively, the "Securities") have not been registered
under the Securities Act. We agree, on our own behalf and on behalf of each
account for which we acquire any Securities, that if in the future we decide to
resell or otherwise transfer such Securities, such Securities may be resold or
otherwise transferred only (i) to the Company or any subsidiary thereof; or (ii)
inside the United States to a person who is a "qualified institutional buyer"
(as defined in Rule 144A under the Securities Act) in a transaction meeting the
requirements of Rule 144A; or (iii) inside the United States to an Institutional
Accredited Investor that, prior to such transfer, furnished to the transfer
agent or registrar for such securities a signaled letter containing certain
representations and agreements relating to the restrictions on transfer or such
securities (the form of which letter can be obtained from such transfer agent or
registrar). or (iv) outside the United States in a transaction meeting the
requirements of Rule 904 under the Securities Act, or (v) pursuant to the
exemption for registration provided by Rule 144 under the Securities Act (if
applicable); or (vi) pursuant to a registration statement which has been
declared effective under the Securities Act (and which constitutes to be
effective at the time of such transfer). We agree that any such transfer of
Securities referred to in this paragraph shall be in accordance with any
applicable securities laws of any State of the United States or any other
applicable jurisdiction and in accordance with the legends set forth on the
Securities.

             We further agree to provide any person purchasing any of the
Securities from us, other than pursuant to clause (vi) above, a notice advising
such purchaser that resales of such securities are restricted as stated herein.
We understand that the registrar and transfer agent for the Securities will not
be required to accept for registration of transfer any Securities except upon
presentation of evidence satisfactory to the Company that we have complied with
the foregoing restrictions on transfer. We further understand that any
Securities will be in the form of definitive physical certificates and that such
certificates will bear a legend (unless the sale of the Securities has been
registered under the Securities Act) reflecting the substance of this paragraph.



                                      B1-2
<PAGE>   104

             We acknowledge that the Company, others and you will rely upon our
confirmations, acknowledgements and agreements set forth herein, and we agree to
notify you promptly in writing if any of our representations or warranties
herein ceases to be accurate and complete.


                                       (Name of Purchaser)

Dated:                   ,             By:
       ------------------ --------        ----------------------------------

                                       Name:
                                            ---------------------------------

                                       Title:
                                             --------------------------------

                                       Address:

                                               ------------------------------

                                               ------------------------------



                                      B1-3
<PAGE>   105
                                                                     Exhibit B-2

          FORM OF CERTIFICATE FOR EXCHANGE OR REGISTRATION OF TRANSFER
             FROM RULE 144A GLOBAL NOTE TO REGULATION S GLOBAL NOTE
                (Pursuant to Section 2.6(a) (i) of the Indenture)

Incyte Pharmaceuticals, Inc.
3174 Porter Drive
Palo Alto, California  94304

State Street Bank and Trust Company of California, N.A.
633 West 5th Street, 12th Floor
Los Angeles, CA  90071
Attn:   Corporate Trust Department
        (Incyte Pharmaceuticals, Inc. 5.5%
        Convertible Subordinated Notes Due 2007)

        Re:  Incyte Pharmaceuticals, Inc. 5.5% Convertible Subordinated Notes
             Due 2007

Dear Ladies and Gentlemen:

        Reference is hereby made to the Indenture, dated as of February 4, 2000
(the "Indenture"), between Incyte Pharmaceuticals, Inc., as issuer (the
"Company") and State Street Bank and Trust Company of California, N.A., as
trustee. Capitalized terms used but not defined herein shall have the meanings
given to them in the Indenture.

        This letter relates to U.S. $150,000,000 principal amount of Notes which
are evidenced by one or more Rule 144A Global Notes (CUSIP No. 45337CAA0) and
held with the Depositary in the name of ____________________________ (the
"Transferor"). The Transferor has requested a transfer of such beneficial
interest in the Notes to a Person who will take delivery thereof in the form of
an equal principal amount of Notes evidenced by one or more Regulation S Global
Notes (CINS No. U45236AA1), which amount, immediately after such transfer, is to
be held with the Depositary through Euroclear or Clearstream Banking or both
(Common Code ___________).

        In connection with such request and in respect of such Notes, the
Transferor hereby certifies that such transfer has been effected in compliance
with the transfer restrictions applicable to the Global Notes and pursuant to
and in accordance with Rule 903 or Rule 904 under the United States Securities
Act of 1933, as amended (the "Securities Act"), and accordingly the Transferor
hereby further certifies that:

        (1)  The offer of the Notes was not made to a person in the United
             States;

        (2)  either:

             (a)  at the time the buy order was originated, the transferee was
                  outside the United States or the Transferor and any person
                  acting on its behalf



                                      B2-1
<PAGE>   106

                  reasonably believed and believes that the transferee was
                  outside the United States; or

             (b)  the transaction was executed in, on or through the facilities
                  of a designated offshore securities market and neither the
                  Transferor nor any person acting on its behalf knows that the
                  transaction was prearranged with a buyer in the United States;

        (3)  no directed selling efforts have been made in contravention of the
             requirements of Rule 904(b) of Regulation S;

        (4)  the transaction is not part of a plan or scheme to evade the
             registration requirements of the Securities Act; and

        (5)  upon completion of the transaction, the beneficial interest being
             transferred as described above is to be held with the Depositary
             through Euroclear or Clearstream Banking or both (Common Code
             ____________).

        (6)  With respect to transfers made in reliance on Rule 144, the Notes
             are being transferred in a transaction permitted by Rule 144 under
             the Securities Act; and with respect to transfer made in reliance
             on Rule 144A, that such Notes are being transferred in accordance
             with Rule 144A under the Securities Act to a transferee that the
             Transferor reasonably believes is purchasing the Notes for its own
             account or an account with respect to which the transferee
             exercises sole investment discretion and the transferee and any
             such account is a "qualified institutional buyer" within the
             meaning of Rule 144A, in a transaction meeting the requirements of
             Rule 144A and in accordance with applicable securities laws of any
             state of the United States or any other jurisdiction.

             In addition, if the sale is made during a restricted period and the
provisions of Rule 903(c)(2) or (3) or Rule 904(c)(1) of Regulation S are
applicable thereto, we confirm that such sale has been made in accordance with
the applicable provisions of Rule 903(c)(2) or (3) or Rule 904(c)(1), as the
case may be.

             Upon giving effect to this request to exchange a beneficial
interest in a Rule 144A Global Note for a beneficial interest in a Regulation S
Global Note, the resulting beneficial interest shall be subject to the
restrictions on transfer applicable to Regulation S Global Notes pursuant to the
Indenture and the Securities Act.



                                      B2-2
<PAGE>   107

             This certificate and the statements contained herein are made for
your benefit and the benefit of the Company and Deutsche Bank Securities Inc.
and Warburg Dillon Read LLC, the initial purchasers of such Notes being
transferred, and you and each of them is entitled to rely on the contents of
this certificate. Terms used in this certificate and not otherwise defined in
the Indenture have the meanings set forth in Regulation S under the Securities
Act.

                                       ------------------------------------
                                       [Insert Name of Transferor]

                                       By:
                                          ---------------------------------
                                          Name:
                                          Title:
Dated:                       ,
      ----------------------- -----

cc:      Incyte Pharmaceuticals, Inc.
         Deutsche Bank Securities Inc.
         Warburg Dillon Read LLC



                                      B2-3
<PAGE>   108

                                                                     Exhibit B-3

          FORM OF CERTIFICATE FOR EXCHANGE OR REGISTRATION OF TRANSFER
             FROM REGULATION S GLOBAL NOTE TO RULE 144A GLOBAL NOTE
                (Pursuant to Section 2.6(a)(ii) of the Indenture)

Incyte Pharmaceuticals, Inc.
3174 Porter Drive
Palo Alto, California  94304

State Street Bank and Trust Company of California, N.A.
633 West 5th Street, 12th Floor
Los Angeles, CA  90071
Attn:   Corporate Trust Department (Incyte Pharmaceuticals, Inc. 5.5%
        Convertible Subordinated Notes Due 2007)

        Re:  Incyte Pharmaceuticals, Inc. 5.5% Convertible Subordinated Notes
             Due 2007

Dear Ladies and Gentlemen:

        Reference is hereby made to the Indenture, dated as of February 4, 2000
(the "Indenture"), among Incyte Pharmaceuticals, Inc., as issuer (the "Company")
and State Street Bank and Trust Company of California, N.A., as trustee.
Capitalized terms used but not defined herein shall have the meanings given to
them in the Indenture.

        This letter relates to U.S. $_______ principal amount of Notes which are
evidenced by one or more Regulation S Global Notes (CINS No. U45236AA1) and held
with the Depositary through [Euroclear] [Clearstream Banking] (Common Code
_________) in the name of ____________________________ (the "Transferor"). The
Transferor has requested a transfer of such beneficial interest in the Notes to
a Person who will take delivery thereof in the form of an equal principal amount
of Notes evidenced by one or more Rule 144A Global Notes (CUSIP No. 45337CAA0),
to be held with the Depositary.

        In connection with such request and in respect of such Notes, the
Transferor hereby certifies that:

                                   [CHECK ONE]

   [ ]  such transfer is being effected pursuant to and in accordance with Rule
        144A under the United States Securities Act of 1933, as amended (the
        "Securities Act") , and, accordingly, the Transferor hereby further
        certifies that the Notes are being transferred to a Person that the
        Transferor reasonably believes is purchasing the Notes for its own
        account, or for one or more accounts with respect to which such Person
        exercises sole investment discretion, and such Person and each such
        account is a "qualified institutional buyer" within the meaning of Rule
        144A in a transaction meeting the requirements of Rule 144A;



                                      B3-1
<PAGE>   109

                                       or

   [ ]  such transfer is being effected pursuant to and in accordance with Rule
        144 under the Securities Act;

                                       or

   [ ]  such transfer is being effected pursuant to an effective registration
        statement under the Securities Act;

                                       or

   [ ]  such transfer is being effected pursuant to an exemption from the
        registration requirements of the Securities Act other than Rule 144A or
        Rule 144, and the Transferor hereby further certifies that the Notes are
        being transferred in compliance with the transfer restrictions
        applicable to the Global Notes and in accordance with the requirements
        of the exemption claimed, which certification is supported by an Opinion
        of Counsel, provided by the transferor or the transferee (a copy of
        which the Transferor has attached to this certification) in form
        reasonably acceptable to the Company and to the Registrar, to the effect
        that such transfer is in compliance with the Securities Act;

and such Notes are being transferred in compliance with any applicable blue sky
securities laws of any state of the United States.

        Upon giving effect to this request to exchange a beneficial interest in
Regulation S Global Notes for a beneficial interest in Rule 144A Global Notes,
the resulting beneficial interest shall be subject to the restrictions on
transfer applicable to Rule 144A Global Notes pursuant to the Indenture and the
Securities Act.



                                      B3-2
<PAGE>   110

        This certificate and the statements contained herein are made for your
benefit and the benefit of the Company and Deutsche Ban Securities Inc. and
Warburg Dillon Read LLC, the initial purchasers of such Notes being transferred,
and you and each of them is entitled to rely on the contents of this
certificate. Terms used in this certificate and not otherwise defined in the
Indenture have the meanings set forth in Regulation S under the Securities Act.


                                       ------------------------------------
                                       [Insert Name of Transferor]

                                       By:
                                          ---------------------------------
                                          Name:
                                          Title:
Dated:                  ,
      ------------------ ------

cc:      Incyte Pharmaceuticals, Inc.
         Deutsche Bank Securities Inc.
         Warburg Dillon Read LLC



                                      B3-3
<PAGE>   111

                                                                     Exhibit B-4

          FORM OF CERTIFICATE FOR EXCHANGE OR REGISTRATION OF TRANSFER
                              OF CERTIFICATED NOTES
                  (Pursuant to Section 2.6(b) of the Indenture)

Incyte Pharmaceuticals, Inc.
3174 Porter Drive
Palo Alto, California  94304

State Street Bank and Trust Company of California, N.A.
633 West 5th Street, 12th Floor
Los Angeles, CA  90071
Attn:   Corporate Trust Department (Incyte Pharmaceuticals, Inc. 5.5%
        Convertible Subordinated Notes Due 2007)

        Re:  Incyte Pharmaceuticals, Inc. 5.5% Convertible Subordinated Notes
             Due 2007

Dear Ladies and Gentlemen:

        Reference is hereby made to the Indenture, dated as of February 4, 2000
(the "Indenture"), among Incyte Pharmaceuticals, Inc., as issuer (the "Company")
and State Street Bank and Trust Company of California, N.A., as trustee.
Capitalized terms used but not defined herein shall have the meanings given to
them in the Indenture.

        This certificate relates to U.S. $__________ aggregate principal amount
of Notes which are held in Certificated Form (CUSIP No. 45337CAA0) in the name
of ______________ (the "Transferor") and is executed in connection with the
exchange or transfer of such securities.

        In connection with such request and in respect of the Notes surrendered
to the Trustee herewith for exchange (the "Surrendered Notes"), the Holder of
such Surrendered Notes hereby certifies that:

                                   [CHECK ONE]

the Surrendered Notes are being acquired for the Transferor's own account,
without transfer;

                                       or

the Surrendered Notes are being transferred to the Company;

                                       or

the Surrendered Notes are being transferred pursuant to and in accordance with
Rule 144A under the United States Securities Act of 1933, as amended (the
"Securities Act"), and, accordingly, the Transferor hereby further certifies
that the Surrendered Notes are being transferred to a Person that the Transferor
reasonably believes is purchasing the Surrendered Notes for its own


                                      B4-1
<PAGE>   112

account, or for one or more accounts with respect to which such Person exercises
sole investment discretion, and such Person and each such account is a
"qualified institutional buyer" within the meaning of Rule 144A, in each case in
a transaction meeting the requirements of Rule 144A;

                                       or

   [ ]  the Surrendered Notes are being transferred in a transaction permitted
        by Rule 144 under the Securities Act;


                                       or

   [ ]  the Surrendered Notes are being transferred pursuant to an effective
        registration statement under the Securities Act;


                                       or

   [ ]  such transfer is being effected pursuant to an exemption from the
        registration requirements of the Securities Act other than Rule 144A or
        Rule 144, and the Transferor hereby further certifies that the Notes are
        being transferred in compliance with the transfer restrictions
        applicable to the Global Notes and in accordance with the requirements
        of the exemption claimed, which certification is supported by an Opinion
        of Counsel, provided by the transferor or the transferee (a copy of
        which the Transferor has attached to this certification) in form
        reasonably acceptable to the Company and to the Registrar, to the effect
        that such transfer is in compliance with the Securities Act;

and the Surrendered Notes are being transferred in compliance with any
applicable blue sky securities laws of any state of the United States.



                                      B4-2
<PAGE>   113

        This certificate and the statements contained herein are made for your
benefit and the benefit of the Company and Deutsche Bank Securities Inc. and
Warburg Dillon Read LLC, the initial purchasers of such Notes being transferred
and you and each of them is entitled to rely on the contents of this
certificate. Terms used in this certificate and not otherwise defined in the
Indenture have the meanings set forth in Regulation S under the Securities Act.

                                       ------------------------------------
                                       [Insert Name of Transferor]

                                       By:
                                          ---------------------------------
                                          Name:
                                          Title:
Dated:                  ,
      ------------------ ------

cc:      Incyte Pharmaceuticals, Inc.
         Deutsche Bank Securities Inc.
         Warburg Dillon Read LLC



                                      B4-3
<PAGE>   114

                                                                     Exhibit B-5

                 FORM OF CERTIFICATE FOR EXCHANGE OR REGISTRATION OF TRANSFER
             FROM RULE 144A GLOBAL NOTE OR REGULATION S GLOBAL NOTE
                              TO CERTIFICATED NOTE
                  (Pursuant to Section 2.6(c) of the Indenture)

Incyte Pharmaceuticals, Inc.
3174 Porter Drive
Palo Alto, California  94304

State Street Bank and Trust Company of California, N.A.
633 West 5th Street, 12th Floor
Los Angeles, CA  90071
Attn:   Corporate Trust Department (Incyte Pharmaceuticals, Inc. 5.5%
        Convertible Subordinated Notes Due 2007)

        Re:  Incyte Pharmaceuticals, Inc. 5.5% Convertible Subordinated Notes
             Due 2007

Dear Ladies and Gentlemen:

        Reference is hereby made to the Indenture, dated as of February 4, 2000
(the "Indenture"), among Incyte Pharmaceuticals, Inc., as issuer (the "Company")
and State Street Bank and Trust Company of California, N.A., as trustee.
Capitalized terms used but not defined herein shall have the meanings given to
them in the Indenture.

        This letter relates to U.S. $__________ aggregate principal amount of
Convertible Notes which are held [in the form of the [Global] [Regulation S]
Security (CUSIP No. 45337CAA0 / CINSNo. U45236AA1) with the Depositary] in the
name of [__________] (the "Transferor") to effect the transfer of the
Securities.

        In connection with such request and in respect of the Notes surrendered
to the Trustee herewith for exchange (the "Surrendered Notes"), the Holder of
such Surrendered Notes hereby certifies that the Notes are being exchanged or
transferred in accordance with the transfer restrictions set forth in the Notes
and that:

                                   [CHECK ONE]

   [ ]  the Surrendered Notes are being transferred to the beneficial owner of
        such Notes;


                                       or

   [ ]  the Surrendered Notes are being transferred pursuant to and in
        accordance with Rule 144A under the United States Securities Act of
        1933, as amended (the "Securities Act"), and, accordingly, the
        Transferor hereby further certifies that the



                                      B5-1
<PAGE>   115

        Surrendered Notes are being transferred to a Person that the Transferor
        reasonably believes is purchasing the Surrendered Notes for its own
        account, or for one or more accounts with respect to which such Person
        exercises sole investment discretion, and such Person and each such
        account is a "qualified institutional buyer" within the meaning of Rule
        144A, in each case in a transaction meeting the requirements of Rule
        144A;


                                       or

   [ ]  the Surrendered Notes are being transferred in a transaction permitted
        by Rule 144 under the Securities Act;


                                       or

   [ ]  the Surrendered Notes are being transferred pursuant to an effective
        registration statement under the Securities Act;


                                       or

   [ ]  such transfer is being effected pursuant to an exemption from the
        registration requirements of the Securities Act other than Rule 144A or
        Rule 144, and the Transferor hereby further certifies that the Notes are
        being transferred in compliance with the transfer restrictions
        applicable to the Global Notes and in accordance with the requirements
        of the exemption claimed, which certification is supported by an Opinion
        of Counsel, provided by the transferor or the transferee (a copy of
        which the Transferor has attached to this certification) in form
        reasonably acceptable to the Company and to the Registrar, to the effect
        that such transfer is in compliance with the Securities Act;

and the Surrendered Notes are being transferred in compliance with any
applicable blue sky securities laws of any state of the United States.

        [IF TRANSFER OR EXCHANGE FROM REGULATION S GLOBAL NOTE ALSO INCLUDE:

        1. We are either not a U.S. person (as defined below) or we have
purchased our beneficial interest in the above referenced Regulation S Global
Note in a transaction that is exempt from the registration requirements under
the Securities Act.

        2. We are delivering this certificate in connection with obtaining a
beneficial interest in Certificated Securities in exchange for our beneficial
interest in the Regulation S Global Note.



                                      B5-2
<PAGE>   116

        For purposes of this certificate, "U.S. person" means (i) any individual
resident in the United States, (ii) any partnership or corporation organized or
incorporated under the laws of the United States, (iii) any estate of which an
executor or administrator is a U.S. person (other than an estate governed by
foreign law and of which at least one executor or administrator is a non-U.S.
person who has sole or shared investment discretion with respect to its assets,
(iv) any trust of which any trustee is a U.S. person (other than a trust of
which at least one trustee is a non-U.S. person who has sole or shared
investment discretion with respect to its assets and no beneficiary of the trust
(and no settlor if the trust is revocable) is a U.S. person), (v) any agency or
branch of a foreign entity located in the United States, (vi) any
non-discretionary or similar account (other than an estate or trust) held by a
dealer or other fiduciary for the benefit or account of a U.S. person, (vii) any
discretionary or similar account (other than an estate or trust) held by a
dealer or other fiduciary organized, incorporated or (if an individual) resident
in the United States (other than such an account held for the benefit or account
of a non-U.S. person), (viii) any partnership or corporation organized or
incorporated under the laws of a foreign jurisdiction and formed by a U.S.
person principally for the purpose of investing in securities not registered
under the Securities Act (unless it is organized or incorporated, and owned, by
accredited investors within the meaning of Rule 501(a) under the Securities Act
who are not natural persons, estates or trusts); provided, however, that the
term "U.S. person" shall not include (A) a branch or agency of a U.S. person
that is located and operating outside the United States for valid business
purposes as a locally regulated branch or agency engaged in the banking or
insurance business, (B) any employee benefit plan established and administered
in accordance with the law, customary practices and documentation of a foreign
country and (C) the international organizations set forth in Section 902(o) (7)
of Regulation S under the Securities Act and any other similar international
organizations, and their agencies, affiliates and pension plans.]

        This certificate and the statements contained herein are made for your
benefit and the benefit of the Company and Deutsche Bank Securities Inc. and
Warburg Dillon Read LLC, the initial purchasers of such Notes being transferred
and you and each of them is entitled to rely on the contents of this
certificate. Terms used in this certificate and not otherwise defined in the
Indenture have the meanings set forth in Regulation S under the Securities Act.


                                       ------------------------------------
                                       [Insert Name of Transferor]

                                       By:
                                          ---------------------------------
                                          Name:
                                          Title:
Dated:                  ,
      ------------------ ------


                                      B5-3
<PAGE>   117

                                                                     Exhibit B-6

                FORM OF LETTER OF REPRESENTATION TO BE DELIVERED
                 BY PURCHASERS OF NOTES PURSUANT TO REGULATION S

Incyte Pharmaceuticals, Inc.
3174 Porter Drive
Palo Alto, California  94304

Deutsche Bank Securities Inc.
Warburg Dillon Read LLC
c/o Deutsche Bank Securities Inc.
101 California Street, 48th Floor
San Francisco, California 94111

Ladies and Gentlemen:

        We are delivering this letter of representation in connection with our
purchase of 5.5% Convertible Subordinated Notes Due 2007 (the "Notes") of Incyte
Pharmaceuticals, Inc., as described in the Offering Memorandum relating to such
offering.

        We hereby certify that:

        1. we are not a "U.S. person" within the meaning of Rule 902(k) of
Regulation S under the United States Securities Act of 1933 (the "Securities
Act");

        2. the Notes are not being purchased on behalf of or for the account or
benefit of a "U.S. person";

        3. we agree to resell such Notes only in accordance with the provisions
of Rule 901 through 905 of Regulation S, pursuant to registration under the
Securities Act, or pursuant to an available exemption from registration; and

        4. we agree not to engage in hedging transactions with regard to the
Notes unless in compliance with the Securities Act.

        We acknowledge that you, the Company, the Transfer Agent for the Notes
and others will rely upon our representations set forth herein, and we agree to
notify you promptly in writing if any of our representations herein ceases to be
accurate and complete.



                                      B6-1
<PAGE>   118

        THE LETTER SHALL BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE WITH, THE
LAWS OF THE STATE OF CALIFORNIA.


                                       ------------------------------------
                                       (Name of Purchaser)

                                       By:
                                       Name:
                                       Title:



                                      B6-2