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                                                                    EXHIBIT 10.7

                   SERIES C PREFERRED STOCK PURCHASE AGREEMENT

                              ARRAY BIOPHARMA INC.

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                                TABLE OF CONTENTS

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RECITALS          .......................................................................................1

SECTION 1.        PURCHASE AND SALE......................................................................1
        1.1       Authorization of Shares................................................................1
        1.2       Sale and Purchase......................................................................1

SECTION 2.        CLOSING................................................................................1

SECTION 3.        REPRESENTATIONS AND WARRANTIES OF THE COMPANY..........................................2
        3.1       Organization, Good Standing and Qualification..........................................2
        3.2       Capitalization.........................................................................2
        3.3       Authorization..........................................................................3
        3.4       Financial Statements...................................................................3
        3.5       Liabilities............................................................................3
        3.6       Changes................................................................................3
        3.7       Material Contracts.....................................................................5
        3.8       Obligations to Related Parties.........................................................5
        3.9       Assets.................................................................................6
       3.10       Intellectual Property..................................................................6
       3.11       Compliance with Other Instruments......................................................7
       3.12       Litigation.............................................................................7
       3.13       Taxes..................................................................................7
       3.14       Employees and Consultants..............................................................7
       3.15       Employee Benefits Matters..............................................................8
       3.16       Registration Rights....................................................................8
       3.17       Governmental Approvals/Third Party Consents............................................8
       3.18       Compliance with Laws...................................................................8
       3.19       Environmental Matters..................................................................9
       3.20       Offering Valid.........................................................................9
       3.21       Accuracy of Information Furnished......................................................9
       3.22       Insurance..............................................................................9
       3.23       Investment Company Act.................................................................9

SECTION 4.        REPRESENTATIONS AND WARRANTIES OF PURCHASERS...........................................9
        4.1       Requisite Power and Authority..........................................................9
        4.2       Investment Representations............................................................10
        4.3       Restrictive Legends...................................................................11

SECTION 5.        CONDITIONS TO CLOSING.................................................................11
        5.1       Conditions to Purchasers' Obligations at the First Closing............................11
        5.2       Conditions to Obligations of the Company at First Closing.............................13
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SECTION 6.        COVENANTS OF THE COMPANY FOR THE PERIOD FOLLOWING CLOSING.............................13
        6.1       Use of Proceeds.......................................................................13
        6.2       Maintenance of Corporate Status.......................................................14
        6.3       Compliance with Governing Documents...................................................14
        6.4       Compliance with Laws, Licenses and Permits; No Infringement...........................14
        6.5       Discharge of Obligations..............................................................14
        6.6       Maintenance of Properties.............................................................14
        6.7       Maintenance of Proprietary Information................................................14
        6.8       Compensation of Directors.............................................................15
        6.9       Books and Records.....................................................................15

SECTION 7.        MISCELLANEOUS.........................................................................15
        7.1       Governing Law.........................................................................15
        7.2       Survival..............................................................................15
        7.3       Successors and Assigns................................................................15
        7.4       Entire Agreement......................................................................15
        7.5       Severability..........................................................................15
        7.6       Amendment and Waiver..................................................................15
        7.7       Delays or Omissions...................................................................16
        7.8       Notices...............................................................................16
        7.9       Expenses..............................................................................16
       7.10       Indemnification by the Company........................................................16
       7.11       Indemnification by the Purchasers.....................................................16
       7.12       Titles and Subtitles..................................................................17
       7.13       Counterparts..........................................................................17
       7.14       Broker's Fees.........................................................................17
       7.15       Arbitration...........................................................................17
       7.16       Exculpation Among Purchasers..........................................................17
       7.17       Pronouns..............................................................................18
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                   SERIES C PREFERRED STOCK PURCHASE AGREEMENT
                              ARRAY BIOPHARMA INC.

         This Series C Preferred Stock Purchase Agreement (the "AGREEMENT") is
made and entered into as of the 31st day of August 2000, by and among ARRAY
BIOPHARMA INC., a Delaware corporation (the "COMPANY"), and each of the
"PURCHASERS" identified on the signature pages hereto.

                                    RECITALS

         A. The Company has authorized the issuance and sale of a total of
1,666,667 shares (the "SHARES") of Series C Preferred Stock of the Company, par
value $0.001 per share.

         B. The Company desires to sell the Shares to Purchasers, and Purchasers
desire to purchase the Shares from the Company, pursuant to the terms and
conditions contained herein.

                                    AGREEMENT

         NOW THEREFORE, in consideration of the mutual covenants, agreements,
conditions, representations, and warranties contained in this Agreement, the
Company and Purchasers hereby each agree as follows:

SECTION 1. PURCHASE AND SALE.

         1.1 AUTHORIZATION OF SHARES. On or prior to the Closing (as defined in
Section 2 below), the Company shall have authorized (i) the sale and issuance to
Purchasers of the Shares; and (ii) such shares of Common Stock issuable upon
conversion of the Shares (the "CONVERSION SHARES"). The Shares and the
Conversion Shares shall have the rights, preferences, privileges and
restrictions set forth in the Amended and Restated Certificate of Incorporation
of the Company, in the form attached hereto as Exhibit A (the "AMENDED
Certificate").

         1.2 SALE AND PURCHASE. Subject to the terms and conditions hereof, at
the Closing (as defined in Section 2 below) the Company hereby agrees to issue
and sell to each Purchaser, severally and not jointly, and each Purchaser agrees
to purchase from the Company, severally and not jointly, the number of Shares
set forth opposite such Purchaser's name on Exhibit B hereto, at the purchase
price of $6.00 per Share.

SECTION 2. CLOSING.

         The closing of the sale and purchase of the Shares under this Agreement
(the "CLOSING") shall take place at 9:00 a.m. on the date hereof, at the offices
of Hogan & Hartson L.L.P., 1800 Broadway, Suite 200, Boulder Colorado 80302, or
at such other time or place as the Company and Purchasers may mutually agree
(such date is hereinafter referred to as the "CLOSING DATE"). At the Closing,
subject to the terms and conditions hereof, the Company will deliver to the
Purchasers certificates representing the number of Shares to be purchased at the
Closing by each

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Purchaser as set forth opposite such Purchaser's name on Exhibit B, against
payment of the purchase price therefor by check or wire transfer made payable to
the order of the Company.

SECTION 3. REPRESENTATIONS AND WARRANTIES OF THE COMPANY.

         Except as set forth on the Disclosure Schedule attached hereto as
Exhibit C, the Company hereby represents and warrants to each Purchaser that is
purchasing the Shares as follows:

         3.1 ORGANIZATION, GOOD STANDING AND QUALIFICATION. The Company is a
corporation duly organized, validly existing and in good standing under the laws
of the State of Delaware. The Company has all requisite corporate power and
authority to own and operate its properties and assets, to execute and deliver
this Agreement, the Amendment No. 1 to Amended and Restated Investor Rights
Agreement in the form attached hereto as Exhibit D (the "AMENDED INVESTOR RIGHTS
AGREEMENT"), and the Amendment No. 2 to Amended and Restated Shareholders
Agreement in the form attached hereto as Exhibit E (the "AMENDED SHAREHOLDERS
AGREEMENT") (collectively with this Agreement and the Amended Certificate, the
"FINANCING DOCUMENTS"), to issue and sell the Shares and to carry out the
provisions of the Financing Documents, and to carry on its business as presently
conducted and as presently proposed to be conducted. The Company is duly
qualified and is authorized to do business and is in good standing in each
jurisdiction in which the nature of its activities and of its properties (both
owned and leased) makes such qualification necessary, except for those
jurisdictions in which failure to do so would not have a material adverse effect
on the Company or its business. The Company does not own, directly or
indirectly, equity securities of any other corporation, limited partnership,
limited liability company or other similar entity. The Company is not a
participant in any joint venture, partnership or similar arrangement.

         3.2 CAPITALIZATION. The authorized capital stock of the Company,
immediately prior to the Closing, will consist of (a) 20,225,000 shares of
Common Stock, 3,865,743 shares of which are issued and outstanding as of August
31, 2000, 4,837,500 shares of which are reserved for issuance to employees and
consultants pursuant to the Company's 1998 Stock Option Plan, as amended,
6,800,000 shares of which are reserved for issuance upon conversion of the
Series A Preferred Stock and warrants, 3,300,000 shares of which are reserved
for issuance upon conversion of the Series B Preferred Stock, 1,725,000 shares
of which are reserved for issuance upon conversion of the Series C Preferred
Stock; and (b) 11,825,000 shares of Preferred Stock, 6,800,000 shares of which
are designated Series A Preferred Stock, 6,635,000 shares of which are issued
and outstanding; 3,300,000 shares of which are designated Series B Preferred
Stock, 3,199,999 shares of which are issued and outstanding; and 1,725,000
shares of which are designated as Series C Preferred Stock, no shares of which
are issued and outstanding. All issued and outstanding shares of the Company's
Common Stock, Series A Preferred Stock and Series B Preferred Stock (i) have
been duly authorized and validly issued, (ii) are fully paid and nonassessable,
and (iii) were issued in compliance with all applicable state and federal laws
concerning the issuance of securities. The rights, preferences, privileges and
restrictions of the Shares are as stated in the Amended Certificate. The
Conversion Shares have been duly and validly reserved for issuance. Except as
may be granted pursuant to the Financing Documents, the Company's Preferred and
Common Stock Purchase Agreement dated May 18, 1998, as amended, the Company's
Series B Stock Purchase Agreement dated November 16, 1999, and the

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agreements referred therein, options granted pursuant to the Company's 1998
Stock Option Plan, and warrants granted pursuant to certain of the Company's
credit facilities, there are no outstanding options, warrants, rights (including
conversion or preemptive rights and rights of first refusal), proxy or
shareholders agreements, or agreements of any kind for the purchase or
acquisition from the Company of any of its securities. When issued in compliance
with the provisions of this Agreement and the Amended Certificate, and upon
receipt of the consideration therefor, the Shares and the Conversion Shares will
be validly issued, fully paid and nonassessable, and will be free of any liens
or encumbrances; provided, however, that the Shares and the Conversion Shares
may be subject to restrictions on transfer under state and federal securities
laws. A schedule describing the anticipated capitalization of the Company as of
the Closing is attached as Exhibit F hereto.

         3.3 AUTHORIZATION. All corporate action on the part of the Company, its
officers, directors and stockholders necessary for the authorization of the
Financing Documents, the performance of all obligations of the Company hereunder
and thereunder at the Closing, and the authorization, sale, issuance and
delivery of the Shares pursuant hereto and the Conversion Shares pursuant to the
Amended Certificate has been taken or will be taken prior to the Closing. The
Financing Documents, when executed and delivered, will be valid and binding
obligations of the Company enforceable against the Company in accordance with
their terms, except (i) as limited by applicable bankruptcy, insolvency,
reorganization, moratorium or other laws of general application affecting
enforcement of creditors' rights; (ii) general principles of equity that
restrict the availability of equitable remedies; and (iii) to the extent that
the enforceability of the indemnification provisions in the Amended Investor
Rights Agreement may be limited by applicable laws. The sale of the Shares and
the subsequent conversion of the Shares into Conversion Shares are not and will
not be subject to any preemptive rights or rights of first refusal that have not
been properly waived or complied with.

         3.4 FINANCIAL STATEMENTS. The Company's unaudited financial statements
for its fiscal year ended June 30, 2000, and its unaudited balance sheet (the
"BALANCE SHEET") as of July 31, 2000 (the "BALANCE SHEET Date"), and unaudited
statements of operations of the Company for the period from July 1, 2000 through
the Balance Sheet Date, made available to the Purchasers in connection with the
investment contemplated hereby (collectively, the "FINANCIAL STATEMENTS"),
fairly present in all material respects the financial position and the results
of operations of the Company for the period covered thereby.

         3.5 LIABILITIES. The Company has no material liabilities and, to the
best of its knowledge, the Company knows of no material contingent liabilities
not disclosed in the Balance Sheet, except current liabilities incurred in the
ordinary course of business subsequent to the Balance Sheet Date which have not
been, either in any individual case or in the aggregate, materially adverse.

         3.6 CHANGES. Since the Balance Sheet Date, and excluding the
transactions contemplated by the Financing Documents, there has not been:

                  (a) Any change in the assets, liabilities, financial condition
or operations of the Company from that reflected in the Financial Statements,
other than changes in the ordinary

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course of business, none of which individually or in the aggregate has had or is
expected to have a material adverse effect on such assets, liabilities,
financial condition or operations of the Company;

                  (b) Any resignation or termination of any key officers of the
Company; and the Company, to the best of its knowledge, does not know of the
impending resignation or termination of employment of any such officer;

                  (c) Any material change, except in the ordinary course of
business, in the contingent obligations of the Company by way of guaranty,
endorsement, indemnity, warranty or otherwise;

                  (d) Any damage, destruction or loss, whether or not covered by
insurance, materially and adversely affecting the properties, business or
prospects or financial condition of the Company;

                  (e) Any waiver by the Company of a valuable right or of a
material debt owed to it;

                  (f) Any direct or indirect loans made by the Company to any
stockholder, employee, officer or director of the Company, other than advances
made in the ordinary course of business;

                  (g) Any material change in any compensation arrangement or
agreement with any employee, officer, director or stockholder of the Company;

                  (h) Any declaration or payment of any dividend or other
distribution of the assets of the
Company;

                  (i) Any labor organization activity;

                  (j) Any debt, obligation or liability incurred, assumed or
guaranteed by the Company, except those for immaterial amounts and for current
liabilities incurred in the ordinary course of business;

                  (k) Any sale, assignment or transfer of any patents,
trademarks, copyrights, trade secrets
or other intangible assets of the Company;

                  (1) Any change in any material agreement to which the Company
is a party or by which it is bound that materially and adversely affects the
business, assets, liabilities, financial condition, operations or prospects of
the Company, including compensation agreements with the Company's employees; or

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                  (m) Any other event or condition of any character that, either
individually or cumulatively, has materially and adversely affected the
business, assets, liabilities, financial condition, operations or prospects of
the Company.

         3.7 MATERIAL CONTRACTS.

                  (a) Except as set forth on Item 3.7(a) of the Disclosure
Schedule, the Company has no, and is not bound by, any contract, agreement,
lease, commitment, or proposed transaction, judgment, order, writ or decree,
written or oral, absolute or contingent, other than (i) contracts for the
purchase of supplies and services that were entered into in the ordinary course
of business and that do not involve more than $20,000, and do not extend for
more than one year beyond the date hereof; (ii) sales contracts entered into in
the ordinary course of business; and (iii) contracts terminable at will by the
Company on no more than 30 days' notice without cost or liability to the Company
and that do not involve any employment or consulting arrangement and are not
material to the conduct of the Company's business. For the purpose of this
paragraph, employment and consulting contracts and contracts with labor unions,
and license agreements and any other agreements relating to the Company's
acquisition or disposition of patent, copyright, trade secret or other
proprietary rights or technology (other than standard end-user license
agreements) shall not be considered to be contracts entered into in the ordinary
course of business. Every contract disclosed on Item 3.7(a) of the Disclosure
Schedule (collectively, the "MATERIAL CONTRACTS") is a legal, valid and binding
obligation, enforceable in accordance with its terms with respect to the Company
and any other parties bound thereby, and true and complete copies of all
Material Contracts have been provided to Purchasers. The Company has not been
given notice that any other party is currently in breach of any of the terms of
any Material Contract. There is no default or event that, with notice or lapse
of time, or both, would conflict with or constitute a breach of any Material
Contract or would result in the creation or imposition of any lien or
encumbrance on the Company, or any of the Company's property. The Company has
not received notice that any party to any Material Contract intends to cancel,
amend or terminate any such agreement.

                  (b) Except as set forth on Item 3.7(b) of the Disclosure
Schedule, the Company has not engaged in the past three months in any discussion
(i) with any representative of any corporation or corporations regarding the
consolidation or merger of the Company with or into any such corporation or
corporations; (ii) with any corporation, partnership, association or other
business entity or any individual regarding the sale, conveyance or disposition
of all or substantially all of the assets of the Company, or a transaction or
series of related transactions in which more than 50% of the voting power of the
Company is or was to be disposed; or (iii) regarding any other form of
acquisition, liquidation, dissolution or winding up of the Company.

         3.8 OBLIGATIONS TO RELATED PARTIES. There are no obligations of the
Company to officers, directors, stockholders, or employees of the Company other
than (i) for payment of salary for services rendered since the commencement of
the Company's most recent payroll period; (ii) reimbursement for reasonable
expenses incurred on behalf of the Company; and (iii) for other standard
employee benefits made generally available to all employees (including stock
option agreements outstanding under any stock option plan approved by the Board
of Directors of the Company). Except as set forth on Item 3.8 of the Disclosure
Schedule, none of the

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officers, directors or stockholders of the Company, or any members of their
immediate families, are indebted to the Company or have any direct or indirect
ownership interest in any firm or corporation with which the Company is
affiliated or with which the Company has a business relationship, or any firm or
corporation which competes with the Company, except that officers, directors
and/or stockholders of the Company may own stock in publicly traded companies
which may compete with the Company. No officer, director or stockholder, or any
member of their immediate families, is, directly or indirectly, interested in
any material contract with the Company (other than such contracts as relate to
any such person's ownership of capital stock or other securities of the
Company). Except as may be disclosed in the Financial Statements, the Company is
not a guarantor or indemnitor of any indebtedness of any other person, firm or
corporation.

         3.9 ASSETS; REAL PROPERTY. The Company has good title to all of its
personal property, including all assets reflected on the balance sheets included
in the Financial Statements or acquired by the Company since the Balance Sheet
Date, all of which are in good operating condition and free and clear of
material restrictions on or conditions to transfer or assignment, and free and
clear of all liens, claims, mortgages, pledges, charges, equities, easements,
rights of way, covenants, conditions, security interests, encumbrances, or
restrictions, except for liens for current taxes or materialmen not yet due and
payable or being contested in good faith and as set forth on Item 3.9 of the
Disclosure Schedule. The Company does not own any real property. Set forth on
Item 3.9 of the Disclosure Schedule is a correct and complete list (including
the amount of annual rents called for and a summary description of the leased
property) of all leases under which the Company is a lessee. The properties and
leases listed on Item 3.9 of the Disclosure Schedule are sufficient for the
conduct of the Company's business as now being and presently planned to be
conducted. The Company holds a valid leasehold interest in all leases listed on
Item 3.9 of the Disclosure Schedule, free of any liens, claims, or encumbrances
granted by the Company, except for those described in the first sentence of this
Section 3.9, and is not in default under any such lease. The Company enjoys
peaceful and undisturbed possession of all premises leased to it from others,
and does not occupy any real property in material violation of any law,
regulations, or decree.

         3.10 INTELLECTUAL PROPERTY. The Company owns or possesses sufficient
legal rights to all patents, trademarks, service marks, trade names, copyrights,
trade secrets, information and other proprietary rights and processes necessary
for its business as now conducted and as currently proposed to be conducted,
without any known infringement of the rights of others. There are no outstanding
options, licenses or agreements of any kind relating to the foregoing, nor is
the Company bound by or a party to any options, licenses or agreements of any
kind with respect to the patents, trademarks, service marks, trade names,
copyrights, trade secrets, licenses, information and other proprietary rights
and processes of any other person or entity other than such licenses or
agreements arising from the purchase of "off the shelf" or standard products.
The Company has received no communication alleging that the Company has violated
or, by conducting its business as proposed, would violate any of the patents,
trademarks, service marks, trade names, copyrights or trade secrets or other
proprietary rights of any other person or entity. The Company is not aware that
any of its employees is obligated under any contract (including licenses,
covenants or commitments of any nature) or other agreement, or subject to any
judgment, decree or order of any court or administrative agency, that would
interfere with his or

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her duties to the Company or that would conflict with the Company's business as
currently proposed to be conducted. Neither the execution nor delivery of this
Agreement, nor the carrying on of the Company's business by the employees of the
Company, nor the conduct of the Company's business as proposed, will, to the
Company's knowledge, conflict with or result in a breach of the terms,
conditions or provisions of, or constitute a default under, any contract,
covenant or instrument under which any employee is now obligated.

         3.11 COMPLIANCE WITH OTHER INSTRUMENTS. The Company is not in violation
or default of any term of its Amended Certificate or Bylaws, or of any provision
of any mortgage, indenture, contract, agreement, instrument or contract to which
it is party or by which it is bound or of any judgment, decree, order, writ or,
to its knowledge, any statute, rule or regulation applicable to the Company
which would materially and adversely affect the business, assets, liabilities,
financial condition, operations or prospects of the Company. The execution,
delivery, and performance of and compliance with the Financing Documents, and
the issuance and sale of the Shares pursuant hereto and of the Conversion Shares
pursuant to the Amended Certificate, will not, with or without the passage of
time or giving of notice, result in any such material violation, or be in
conflict with or constitute a default under any such term, or result in the
creation of any mortgage, pledge, lien, encumbrance or charge upon any of the
properties or assets of the Company or the suspension, revocation, impairment,
forfeiture or nonrenewal of any permit license, authorization or approval
applicable to the Company, its business or operations or any of its assets or
properties.

         3.12 LITIGATION. There are no actions, suits, or legal, administrative,
or other proceedings or investigations pending or, to the best of the Company's
knowledge, threatened before any court, agency, or other tribunal to which the
Company is a party or against or affecting any of the property, assets,
businesses, or financial condition of the Company. The Company is not in default
with respect to any order, writ, injunction, or decree of any federal, state,
local or foreign court, department, agency, or instrumentality to which it is a
party.

         3.13 TAXES. The Company has timely filed all federal, state, county,
local and foreign tax returns and reports within the times and in the manner
prescribed by law and has paid (or made adequate provision in the Financial
Statements for) all taxes shown due on such returns, as well as all other
assessments and penalties which have become due and payable. The Company's
federal income and other tax returns have not been audited by the Internal
Revenue Service or any other taxing authority and no notice of audit has been
received. The Company has received no notice of any disputes, deficiency
assessments, or proposed adjustments to taxes payable by the Company.

         3.14 EMPLOYEES AND CONSULTANTS. Except as set forth on Item 3.14 of the
Disclosure Schedule, the Company has not entered into any arrangement with any
present or former employee that will result in any obligation of the Company to
make any payment to such employee upon termination of his or her employment with
the Company. Item 3.14 of the Disclosure Schedule lists all key executive
officers of the Company with whom the Company has entered into an employment
agreement. True and complete copies of all written employment agreements with
the key executive officers of the Company listed on Item 3.14 of the Disclosure
Schedule have been made available to Purchasers prior to the Closing Date. To
the Company's

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knowledge, no employee of or consultant to the Company is in material violation
of any term of any employment contract or any other contract or agreement
relating to the relationship of any such employee or consultant with the
Company. The Company has not received notice that any executive officer intends
to terminate his employment with the Company, nor does the Company have any
present intention to terminate the employment of any executive officer. To the
Company's knowledge, none of its employees are obligated under any contract
(including licenses, covenants, or commitments of any nature) or other
agreement, or subject to any judgment, decree, or order of any court or
administrative agency, that would interfere with the use of his/her reasonable
diligence to promote the interests of the Company or that would conflict with
the Company's business as proposed to be conducted. Neither the execution nor
delivery of this Agreement, nor the carrying on of the Company's business by the
employees of the Company, nor the conduct of the Company's business as proposed,
will, to the Company's knowledge, conflict with or result in a breach of the
terms, conditions or provisions of, or constitute a default under, any contract,
covenant, or instrument under which any of such employees is obligated, which
conflict, breach, or default would be materially adverse to the Company.

         3.15 EMPLOYEE BENEFITS MATTERS. The Company does not maintain or
contribute to any plan or arrangement that constitutes an "employee pension
benefit plan" as defined in Section 3(2) of ERISA except as set forth on Item
3.15, and is not obligated to contribute to or accrue or pay benefits under any
deferred compensation or retirement funding arrangement.

         3.16 REGISTRATION RIGHTS. Except as required pursuant to the Amended
Investor Rights Agreement, the Company is presently not under any obligation,
and has not granted any rights, to register any of the Company's presently
outstanding securities or any of its securities that may hereafter be issued.

         3.17 GOVERNMENTAL APPROVALS/THIRD PARTY CONSENTS. All consents,
approvals, or authorizations of, or registrations, qualifications, designations,
declarations, or filings with any federal or state governmental authority, and
all consents, approvals or authorizations of any third party required in
connection with the execution of the Financing Documents and the performance of
the transactions contemplated thereby (including the issuance and sale of the
Shares) have been obtained by the Company. The Company has, or has rights to
acquire, all licenses, permits, and other similar authority necessary for the
conduct of its business as now being conducted by it and as planned to be
conducted, the lack of which could materially and adversely affect the
operations or condition, financial or otherwise, of the Company, and it is not
in default in any material respect under any of such licenses, permits or other
similar authority.

         3.18 COMPLIANCE WITH LAWS. The Company (a) has complied with and is in
compliance in all material respects with all foreign, federal, state and local
statutes, laws, ordinances, regulations, rules, judgments, orders and decrees
applicable to it and its assets, business and operations, and (b) has received
no written notice of any claim of default under or violation of any statute,
law, ordinance, regulation, rule, judgment, order or decree except for any such
noncompliance or claim of default or violation, if any, which in the aggregate
do not and will not have a material adverse effect the property, operations,
financial condition or prospects of the Company.

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         3.19 ENVIRONMENTAL MATTERS. The Company is in compliance in all
material respects with all environmental and occupational health and safety laws
and, to its knowledge, except as set forth on Item 3.19 of the Disclosure
Schedule, no material expenditures are or will be required in order to comply
with any such laws.

         3.20 OFFERING VALID. Assuming the accuracy of the representations and
warranties of the Purchasers contained in Section 4 hereof, the offer, sale and
issuance of the Shares and the Conversion Shares will be exempt from the
registration requirements of the Securities Act of 1933, as amended (the
"SECURITIES ACT") and will have been registered or qualified, or are exempt from
registration and qualification, under the registration, permit or qualification
requirements of all applicable state securities laws.

         3.21 ACCURACY OF INFORMATION FURNISHED. The Financing Documents, as
well as any exhibit, certificate, written statement, material or information
furnished to the Purchasers by or on behalf of the Company pursuant thereto or
in connection with the transactions contemplated thereby, do not contain any
untrue statement of a material fact or omit to state any material fact that is
necessary to make the statements contained herein or therein not misleading.

         3.22 INSURANCE. The Company has obtained fire and casualty insurance
policies with coverage customary for companies similarly situated to the
Company.

         3.23 INVESTMENT COMPANY ACT. The Company is not an "investment
company," or a company "controlled" by an "investment company," within the
meaning of the Investment Company Act of 1940, as amended.

SECTION 4. REPRESENTATIONS AND WARRANTIES OF PURCHASERS.

         Each Purchaser makes the following representations and warranties to
the Company as to itself that:

         4.1. REQUISITE POWER AND AUTHORITY. Purchaser is an individual, or a
corporation, limited liability company, or limited partnership duly organized,
validly existing and in good standing under the laws of the jurisdiction of its
formation, and has all requisite limited liability company, partnership or
corporate power and authority to own its assets and operate its business.
Purchaser has all necessary corporate, limited liability company or partnership
power and authority under all applicable provisions of law to execute and
deliver each of the Financing Documents to which it is a party and to carry out
their provisions. All action on Purchaser's part required for the lawful
execution and delivery of the Financing Documents have been or will be
effectively taken prior to each Closing Date. Upon their execution and delivery,
the Financing Documents will be valid and binding obligations of Purchaser,
enforceable in accordance with their terms, except (i) as limited by applicable
bankruptcy, insolvency, reorganization, moratorium or other laws of general
application affecting enforcement of creditors' rights; (ii) general principles
of equity that restrict the availability of equitable remedies; and (iii) to the
extent that the enforceability of the indemnification provisions of the Amended
Investor Rights Agreement may be limited by applicable laws.

                                       9
<PAGE>   13

         4.2. INVESTMENT REPRESENTATIONS. Purchaser understands that the Shares
have not been registered under the Securities Act. Purchaser also understands
that the Shares are being offered and sold pursuant to an exemption from
registration contained in the Securities Act based in part upon Purchaser's
representations contained in this Agreement. Purchaser hereby represents and
warrants as follows:

                  (a) PURCHASER BEARS ECONOMIC RISK. Purchaser has substantial
experience in evaluating and investing in private placement transactions of
securities in companies similar to the Company so that it is capable of
evaluating the merits and risks of its investment in the Company and has the
capacity to protect its own interests. Purchaser must bear the economic risk of
this investment indefinitely unless the Shares are registered pursuant to the
Securities Act, or an exemption from registration is available. Purchaser
understands that there is no assurance that any exemption from registration
under the Securities Act will be available and that, even if available, such
exemption may not allow Purchaser to transfer all or any portion of the Shares
under the circumstances, in the amounts or at the times Purchaser might propose.

                  (b) ACQUISITION FOR OWN ACCOUNT. Purchaser is acquiring the
Shares for Purchaser's own account for investment purposes only, and not with a
view towards their distribution.

                  (c) PURCHASER CAN PROTECT ITS INTEREST. Purchaser represents
that by reason of its, or of its management's, business or financial experience,
Purchaser has the capacity to protect its own interests in connection with the
transactions contemplated in the Financing Documents.

                  (d) ACCREDITED INVESTOR. Purchaser represents that it is an
"accredited investor" within the meaning of Regulation D under the Securities
Act.

                  (e) COMPANY INFORMATION. Purchaser has received and read the
Financial Statements and has had an opportunity to ask questions of, and receive
answers from, directors, officers and management of the Company relating to the
Company's business, management and financial affairs and to the terms and
conditions of this investment, and has had the opportunity to review the
Company's operations and facilities.

                  (f) RULE 144. Purchaser acknowledges and agrees that the
Shares must be held indefinitely unless they are subsequently registered under
the Securities Act or an exemption from such registration is available.
Purchaser has been advised or is aware of the provisions of Rule 144 promulgated
under the Securities Act, which permits limited resale of shares purchased in a
private placement subject to the satisfaction of certain conditions, including,
among other things: the availability of certain current public information about
the Company, the resale occurring not less than one year after a party has
purchased and paid for the security to be sold, the sale being through an
unsolicited "broker's transaction" or in transactions directly with a market
maker (as said term is defined under the Securities Act) and the number of
shares being sold during any three-month period not exceeding specified
limitations.

                                       10
<PAGE>   14

                  (g) RESIDENCE. The residence of Purchaser (if an individual),
or the office or offices of the Purchaser in which its investment decision was
made is located at the address or addresses of the Purchaser as stated in the
Company's shareholder records.

         4.3 RESTRICTIVE LEGENDS. Purchaser agrees to the imprinting, so long as
required by law, of a legend on certificates representing all of the Shares or
the Conversion Stock to the following effect:

"THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED UNDER
THE SECURITIES ACT OF 1933, AS AMENDED, OR THE SECURITIES LAWS OF ANY STATE AND
MAY NOT BE SOLD OR OTHERWISE DISPOSED OF EXCEPT PURSUANT TO AN EFFECTIVE
REGISTRATION STATEMENT UNDER SUCH ACT AND APPLICABLE STATE SECURITIES LAWS OR
PURSUANT TO AN APPLICABLE EXEMPTION TO THE REGISTRATION REQUIREMENTS OF SUCH ACT
OR SUCH LAWS.

THE SHARES OF STOCK REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO AN AMENDED
AND RESTATED SHAREHOLDERS AGREEMENT DATED AS OF NOVEMBER 19, 1999, AS MAY BE
AMENDED FROM TIME TO TIME, AND SAID SHARES MAY NOT BE SOLD, TRANSFERRED,
ASSIGNED, HYPOTHECATED OR OTHERWISE DISPOSED OF EXCEPT IN ACCORDANCE WITH THE
TERMS OF SUCH AGREEMENT. SUCH AGREEMENT MAY BE EXAMINED AT THE PRINCIPAL PLACE
OF BUSINESS OF THE COMP ANY AND A COPY THEREOF WILL BE FURNISHED WITHOUT CHARGE
TO THE HOLDER OF THIS CERTIFICATE UPON RECEIPT BY THE COMPANY AT ITS PRINCIPAL
PLACE OF BUSINESS OR REGISTERED OFFICE OF A WRITTEN REQUEST FROM THE
SHAREHOLDER."

SECTION 5. CONDITIONS TO CLOSING.

         5.1 CONDITIONS TO PURCHASERS' OBLIGATIONS AT THE CLOSING. Purchasers'
obligations to purchase the Shares at the Closing are subject to the
satisfaction, at or prior to the Closing, of the following conditions:

                  (a) REPRESENTATIONS AND WARRANTIES TRUE; PERFORMANCE OF
OBLIGATIONS. The representations and warranties made by the Company in Section 3
hereof shall be true and correct in all material respects as of the Closing Date
with the same force and effect as if they had been made as of the Closing Date,
and the Company shall have performed all obligations and conditions herein
required to be performed or observed by it on or prior to the Closing.

                  (b) LEGAL INVESTMENT. On the Closing Date, the sale and
issuance of the Shares, and the proposed issuance of the Conversion Shares,
shall be legally permitted by all laws and regulations to which Purchasers and
the Company are subject.

                  (c) CONSENTS, PERMITS, AND WAIVERS. The Company shall have
obtained any and all consents, permits and waivers necessary or appropriate for
consummation of the

                                       11
<PAGE>   15

transactions contemplated by the Financing Documents (except for such as may be
properly obtained subsequent to the Closing).

                  (d) FILING OF AMENDED CERTIFICATE. The Amended Certificate
shall have been filed with the Secretary of State of the State of Delaware.

                  (e) CORPORATE DOCUMENTS. The Company shall have delivered to
Purchasers or their counsel, copies of all corporate documents of the Company as
Purchasers shall reasonably request.

                  (f) RESERVATION OF CONVERSION SHARES. The Conversion Shares
issuable upon conversion of the Shares shall have been duly authorized and
reserved for issuance upon such conversion.

                  (g) CERTIFICATES. The Company shall have delivered to
Purchasers:

                           (1) proof of filing of the Amended Certificate, and a
certificate, as of the most recent practical date, of the Secretary of State of
Delaware as to the Company's good standing;

                           (2) a certificate of the Secretary of the Company
dated as of the Closing Date, certifying as to (i) the incumbency of the
officers of the Company executing the Financing Agreements and all other
documents executed and delivered in connection therewith; (ii) a copy of the
Amended Certificate, in effect as of the Closing Date; (iii) a copy of the
Bylaws of the Company, in effect as of the Closing Date; and (iv) a copy of the
resolutions or consents of the Board of Directors and stockholders of the
Company authorizing and approving the Company's execution, delivery and
performance of the Financing Agreements; and

                           (3) a certificate, executed by the Chief Executive
Officer of the Company as of the Closing Date, certifying to the fulfillment of
all of the conditions of the Purchasers' obligations under this Agreement, as
set forth in this Section 5.

                  (h) AMENDED INVESTOR RIGHTS AGREEMENT. The Amended Investor
Rights Agreement shall have been executed and delivered by the parties thereto.

                  (i) AMENDED SHAREHOLDERS AGREEMENT. The Amended Shareholders
Agreement shall have been executed and delivered by the parties thereto.

                  (j) LEGAL OPINION. The Purchasers shall have received from
legal counsel to the Company an opinion addressed to them, dated as of the
Closing Date, in substantially the form attached hereto as Exhibit ------- G.

                  (k) PROCEEDINGS AND DOCUMENTS. All corporate and other
proceedings in connection with the transactions contemplated at the Closing
hereby and all documents and instruments incident to such transactions shall be
reasonably satisfactory in substance and form

                                       12
<PAGE>   16

to the Purchasers and their special counsel, and the Purchasers and their
special counsel shall have received all such counterpart originals or certified
or other copies of such documents as they may reasonably request.

         5.2 CONDITIONS TO OBLIGATIONS OF THE COMPANY AT CLOSING. The Company's
obligation to issue and sell the Shares at the Closing is subject to the
satisfaction, on or prior to the Closing, of the following conditions:

                  (a) REPRESENTATIONS AND WARRANTIES TRUE. The representations
and warranties made by Purchasers in Section 4 hereof shall be true and correct
in all material respects at the Closing Date, with the same force and effect as
if they had been made on and as of said date.

                  (b) PERFORMANCE OF OBLIGATIONS. Purchasers shall have
performed and complied with all agreements and conditions herein required to be
performed or complied with by Purchasers on or before the Closing.

                  (c) FILING OF AMENDED CERTIFICATE. The Amended Certificate
shall have been filed with the Secretary of State of the State of Delaware.

                  (d) AMENDED INVESTOR RIGHTS AGREEMENT. The Amended Investor
Rights Agreement shall have been executed and delivered by the Purchasers.

                  (e) AMENDED SHAREHOLDERS AGREEMENT. The Amended Shareholders
Agreement shall have been executed and delivered by the Purchasers.

                  (f) CONSENTS, PERMITS, AND WAIVERS. The Company shall have
obtained any and all consents, permits and waivers necessary or appropriate for
consummation of the transactions contemplated by the Financing Documents (except
for such as may be properly obtained subsequent to the Closing).

                  (g) MINIMUM INVESTMENT. The Purchasers shall purchase at least
1,666,667 Shares in the aggregate at the Closing.

SECTION 6. COVENANTS OF THE COMPANY FOR THE PERIOD FOLLOWING CLOSING.

         Until the date upon which all Shares held by Purchasers (including any
capital stock of the Company issued upon conversion of the Shares) are no longer
outstanding, the Company covenants to each Purchaser and agrees as follows:

         6.1 USE OF PROCEEDS. The Company shall use all proceeds from the sale
of the Shares to Purchasers pursuant to this Agreement for financing of
expenditures related to product

                                       13
<PAGE>   17

development, equipment and facilities expansion, funding ongoing operating costs
and general working capital.

         6.2 MAINTENANCE OF CORPORATE STATUS. The Company shall maintain, and
shall cause each affiliate to maintain, its corporate or partnership existence
in good standing or effective under the laws of its jurisdiction of organization
and any other states or jurisdictions in which its failure to qualify as a
foreign corporation or entity would have a material adverse effect on its
operations or financial condition.

         6.3 COMPLIANCE WITH GOVERNING DOCUMENTS. The Company shall comply, and
shall cause each affiliate to comply, in all material respects with its Amended
Certificate, Bylaws or other governing documents.

         6.4 COMPLIANCE WITH LAWS, LICENSES AND PERMITS; NO INFRINGEMENT. The
Company shall comply with all applicable federal, state, local, foreign and
other laws, regulations and ordinances, and with all applicable federal, state,
local and foreign governmental licenses and permits necessary for conducting its
business, except to the extent that any noncompliance would not have a material
adverse effect upon the Company. The Company shall not knowingly engage in any
activities that infringe upon the intellectual property rights of any other
person, corporation, partnership or other entity which could have a material
adverse effect upon the Company.

         6.5 DISCHARGE OF OBLIGATIONS. The Company shall pay and discharge all
taxes, assessments, and governmental charges lawfully levied or imposed upon it
(in each case before they become delinquent and before penalties accrue), all
lawful claims for labor, materials, supplies and rents, and all other debts and
liabilities that if unpaid would by law be a lien or charge upon any of the
asserts or properties of the Company or lead to suspension of the business of
the Company (except to the extent contested in good faith by the Company and for
which adequate reserves are established).

         6.6 MAINTENANCE OF PROPERTIES. The Company shall maintain all real and
personal property used in the business of the Company in good operating
condition, and shall make all repairs, renewals, replacements, additions and
improvements to those properties as are necessary or appropriate in the ordinary
course of business.

         6.7 MAINTENANCE OF PROPRIETARY INFORMATION. The Company shall maintain
all proprietary information, and all applications and registrations therefor
owned or held by the Company, in full force and effect, except as otherwise
determined in the ordinary course of business. The Company shall not encumber or
license others to use its proprietary information owned by it except in the
ordinary course of the Company's business, and shall maintain the
confidentiality and trade secret status of all proprietary information that is
confidential except contemplated hereby. All statements as to factual matters
contained in any certificate or other instrument delivered by or on behalf of
the Company pursuant hereto in connection with the transactions contemplated
hereby shall be deemed to be representations and warranties by the Company
hereunder solely as of the date of such certificate or instrument.

                                       14
<PAGE>   18

         6.8 COMPENSATION OF DIRECTORS. Each member of the Board of Directors
shall be entitled to (a) customary liability insurance obtained at commercially
reasonable rates, and (b) reimbursement by the Company for all out-of-pocket
expenses, including, without limitation, travel expenses, incurred by such
director in connection with the performance of such directors duties, subject to
approval by the Board of Directors, such approval not be unreasonably withheld.

         6.9 BOOKS AND RECORDS. The Company shall, and shall cause each
affiliate to, keep proper books of records and accounts, in which full and
correct entries shall be made of all financial transactions and the assets and
business of the Company and each affiliate, in accordance with generally
accepted accounting principles in effect from time to time. The Company shall
provide Purchasers with access to all such books and records and allow
Purchasers to make copies and abstracts thereof at reasonable times.

SECTION 7. MISCELLANEOUS.

         7.1 GOVERNING LAW. This Agreement shall be governed by the laws of the
State of Colorado as such laws are applied to agreements between Colorado
residents entered into and performed entirely in Colorado, except that the
Delaware General Corporation Law will govern as to matters of corporate law.

         7.2 SURVIVAL. The representations, warranties, covenants and agreement
made herein shall survive any investigation made by any Purchaser and the
closing of the transactions contemplated hereby. All statements as to factual
matters contained in any certificate or other instrument delivered by or on
behalf of the Company pursuant hereto in connection with the transactions
contemplated hereby shall be deemed to be representations and warranties by the
Company hereunder solely as of the date of such certificate or instrument.

         7.3 SUCCESSORS AND ASSIGNS. Except as otherwise expressly provided
herein, the provisions hereof shall inure to the benefit of, and be binding
upon, the successors, assigns, heirs, executors and administrators of the
parties hereto and shall inure to the benefit of and be enforceable by each
person who shall be a holder of the Shares from time to time.

         7.4 ENTIRE AGREEMENT. The Financing Documents, the Exhibits and
Schedules hereto, and the other documents delivered pursuant hereto constitute
the full and entire understanding and agreement between the parties with regard
to the subjects hereof and no party shall be liable or bound to any other in any
manner by any representations, warranties, covenants and agreements except as
specifically set forth herein and therein.

         7.5 SEVERABILITY. In case any provision of this Agreement 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.

         7.6 AMENDMENT AND WAIVER. This Agreement may be amended or modified
only upon the written consent of the Company, and the holders representing at
least two-thirds of the

                                       15
<PAGE>   19

Shares (treated as if converted and including any Conversion Shares into which
the Shares have been converted that have not been sold).

         7.7 DELAYS OR OMISSIONS. It is agreed that no delay or omission to
exercise any right, power or remedy accruing to any party, upon any breach,
default or noncompliance by another party under any of the Financing Documents,
shall impair any such right, power or remedy, nor shall it be construed to be a
waiver of any such breach, default or noncompliance, or any acquiescence
therein, or of or in any similar breach, default or noncompliance thereafter
occurring. It is further agreed that any waiver, permit, consent or approval of
any kind or character of any breach, default or noncompliance under any of the
Financing Documents or any waiver of any provisions or conditions of any of the
Financing Documents must be in writing and shall be effective only to the extent
specifically set forth in such writing. All remedies under any of the Financing
Documents, under any law or otherwise afforded to any party, shall be cumulative
and not alternative.

         7.8 NOTICES. All notices required or permitted hereunder shall be in
writing and shall be deemed effectively given: (i) upon personal delivery to the
party to be notified; (ii) when sent by confirmed facsimile if sent during
normal business hours of the recipient, if not, then on the next business day;
(iii) three (3) business days after having been sent by registered or certified
mail, return receipt requested, postage prepaid; or (iv) one (1) day after
deposit with a nationally recognized overnight courier, specifying next day
delivery, with written verification of receipt. All communications shall be sent
to the Company at its principal place of business and to Purchasers at the
addresses set forth in the shareholder records of the Company or at such other
address as the Company or Purchaser may designate by ten (10) days advance
written notice to the other parties hereto.

         7.9 EXPENSES. The Company hereby agrees to reimburse each Purchaser for
its out-of-pocket expenses incurred in connection with the transactions
contemplated hereby, including all expenses incurred in connection with its due
diligence examination of the Company, the preparation and negotiation of the
Financing Documents, including the reasonable fees and expenses of special
counsel to the Purchasers, (HELLER EHRMAN WHITE & MCAULIFFE) and in connection
with the enforcement of rights and remedies of the Purchasers hereunder and
under the Amended Shareholders Agreement and all other documents evidencing the
transactions contemplated herein.

         7.10 INDEMNIFICATION BY THE COMPANY. The Company agrees to indemnify
and hold each Purchaser harmless against any loss, liability, damage or expense
(including reasonable legal fees and costs) which such Purchasers may suffer,
sustain or become subject to as a result of or in connection with the breach by
the Company of any representation, warranty, covenant or agreement of the
Company contained in the Financing Documents.

         7.11 INDEMNIFICATION BY THE PURCHASERS. Each Purchaser, severally and
not jointly, agrees to indemnify and hold the Company harmless against any loss,
liability, damage or expense (including reasonable legal fees and costs) which
the Company may suffer, sustain or become subject to as a result of or in
connection with the breach by such Purchaser of any

                                       16
<PAGE>   20

representation, warranty, covenant or agreement of such Purchaser contained in
the Financing Documents.

         7.12 TITLES AND SUBTITLES. The titles of the sections and subsections
of the Agreement are for convenience of reference only and are not to be
considered in construing this Agreement.

         7.13 COUNTERPARTS. This Agreement may be delivered via facsimile and
may be executed in any number of counterparts, each of which shall be an
original, but all of which together shall constitute one instrument.

         7.14 BROKER'S FEES. Each party hereto represents and warrants that no
agent, broker, investment banker, person or firm acting on behalf of or under
the authority of such party hereto is or will be entitled to any broker's or
finder's fee or any other commission directly or indirectly in connection with
the transactions contemplated herein. Each party hereto further agrees to
indemnify each other party for any claims, losses or expenses incurred by such
other party as a result of the representation in this Section 7.14 being untrue.

         7.15 ARBITRATION. The parties hereby covenant and agree that any legal
suit, dispute, claim, demand, controversy or cause of action of every kind and
nature whatsoever, known or unknown, fixed or contingent, that any party may now
have or at any time in the future claim to have based in whole or in part, or
arising from or out of or that in any way is related to the negotiations,
execution, interpretation or enforcement of this Agreement (collectively, the
"DISPUTES") shall be completely and finally settled by submission of any such
Disputes to arbitration under the rules of the American Arbitration Association
("AAA") then in effect. There shall be one arbitrator, and such arbitrator shall
be chosen by mutual agreement of the parties in accordance with AAA rules.
Unless the parties agree otherwise, the arbitration proceedings shall take place
in the Denver, Colorado metropolitan area. The arbitrator shall apply Colorado
law to all issues in dispute, except issues with respect to corporate law in
which case the arbitrator shall apply Delaware law, in accordance with Section
7.1 above. Notice of demand for arbitration shall be filed in writing with the
other party to this Agreement and with the AAA. In no event shall the demand for
arbitration be made after the date when institution of legal or equitable
proceedings based on such Dispute would be barred by the applicable statute of
limitations. The findings of the arbitrator shall be final and binding on the
parties. Judgment on such award may be entered in any court of competent
jurisdiction, or application may be made to that court for a judicial acceptance
of the award and an order or enforcement, as the party seeking to enforce that
award may elect. The prevailing party in any such action shall be entitled to
receive from the losing party all reasonable costs and expenses, including the
reasonable fees of attorneys, accountants, and other experts, incurred by the
prevailing party in investigating and prosecuting (or defending) such action,
together with any such fees which may be incurred in enforcing any award of
judgment.

         7.16 EXCULPATION AMONG PURCHASERS. Each Purchaser acknowledges that it
is not relying upon any person, firm, or corporation, other than the Company and
its officers and directors, in making its investment or decision to invest in
the Company.

                                       17
<PAGE>   21

                  Each Purchaser agrees that no Purchaser nor the respective
controlling persons, officers, directors, partners, agents, or employees of any
Purchaser shall be liable for any action heretofore or hereafter taken or
omitted to be taken by any of them in connection with the Shares and Conversion
Shares.

         7.17 PRONOUNS. All pronouns contained herein, and any variations
thereof, shall be deemed to refer to the masculine, feminine or neutral,
singular or plural, as the identity of the parties hereto may require.

                            [Signature Pages Follow]

                                       18
<PAGE>   22

         IN WITNESS WHEREOF, the parties hereto have executed this Agreement as
of the date above first written.

COMPANY:

ARRAY BIOPHARMA INC.                           PURCHASERS:

By: /s/ ROBERT CONWAY                          FRAZIER HEALTHCARE II, L.P.
    --------------------------------------
    Robert Conway, Chief Executive Officer     By:    /s/ ROBERT W. OVERELL
                                                   -----------------------------
                                               Name:  Robert W. Overell
                                                     ---------------------------
                                               Title: General Partner
                                                      --------------------------

                                               ARCH VENTURE FUND III, L.P.
                                               By:  Arch Venture Partners, LLC,
                                                      its General Partner

                                               By:    /s/ ROBERT T. NELSON
                                                   -----------------------------
                                               Name:  Robert T. Nelson
                                                     ---------------------------
                                               Title: Managing Director
                                                      --------------------------

                                               ROVENT II LIMITED PARTNERSHIP
                                               By:  Advent International Limited
                                                       Partnership, its General
                                                       Partner
                                               By:  Advent International
                                                     Corporation,
                                                       its General Partner

                                               By:    /s/ JASON FISHERMAN
                                                   -----------------------------
                                               Name:  Jason Fisherman
                                                     ---------------------------
                                               Title: Vice President
                                                      --------------------------

                                               MITSUI & CO. (U.S.A.), INC.

                                               By:    /s/ YOUICHIRO ENDO
                                                   -----------------------------
                                               Name:  Youichiro Endo
                                                     ---------------------------
                                               Title: General Manager
                                                      --------------------------

                                               FALCON TECHNOLOGY PARTNERS, L.P.,

                                               By:   /s/ JAMES L. RATHMANN
                                                   -----------------------------
                                                     James L. Rathmann,
                                                       General Partner

<PAGE>   23

                                  BOULDER VENTURES II, L.P.

                                  By: /s/ KYLE LEFKOFF
                                      ------------------------------------------
                                        Kyle Lefkoff, General Partner

                                  BOULDER VENTURES II, (ANNEX) L.P.

                                  By:  /s/ KYLE LEFKOFF
                                      ------------------------------------------
                                        Kyle Lefkoff, General Partner

                                  THE CARUTHERS FAMILY, L.L.C.

                                  By:  /s/ MARVIN H. CARUTHERS
                                      ------------------------------------------
                                        Marvin H. Caruthers, Ph.D.,  Manager

                                  /s/ DAVID SNITMAN
                                  ----------------------------------------------
                                  DAVID SNITMAN, PH.D.

                                  /s/ ANTHONY D. PISCOPIO
                                  ----------------------------------------------
                                  ANTHONY D. PISCOPIO, PH.D.

                                  /s/ K.C. NICOLAOU
                                  ----------------------------------------------
                                  K.C. NICOLAOU, PH.D.

                                  /s/ FRANK A. BONSAL
                                  ----------------------------------------------
                                  FRANK A. BONSAL, JR.

                                  /s/ MICHAEL CARRUTHERS
                                  ----------------------------------------------
                                  MICHAEL CARRUTHERS

                                  /s/ CHRISTOPHER D. OZEROFF
                                  ----------------------------------------------
                                  CHRISTOPHER D. OZEROFF

                                  /s/ WILLIAM R. ROBERTS
                                  ----------------------------------------------
                                  WILLIAM R. ROBERTS

<PAGE>   24

                                  /s/ KIRBY L. CRAMER
                                  ----------------------------------------------
                                  KIRBY L. CRAMER

                                  /s/ JOSEPH LEFKOFF
                                  ----------------------------------------------
                                  JOSEPH LEFKOFF

                                  VECTOR LATER-STAGE EQUITY FUND II, L.P.
                                  By:  Vector Fund Management II, L.L.C., its
                                       General Partner

                                  By:  /s/ BARCLAY A. PHILLIPS
                                     -------------------------------------------
                                  Print Name:  Barclay A. Phillips
                                              ----------------------------------
                                  Title:  Managing Director
                                         ---------------------------------------

                                  VECTOR LATER-STAGE EQUITY FUND II (Q.P.), L.P.
                                  By:  Vector Fund Management II, L.L.C., its
                                       General Partner

                                  By:  /s/ BARCLAY A. PHILLIPS
                                     -------------------------------------------
                                  Print Name:  Barclay A. Phillips
                                              ----------------------------------
                                  Title:  Managing Director
                                         ---------------------------------------

                                  MOSAIX VENTURES, LP
                                  By:  Mosaix Ventures Management, LLC,
                                       its General Partner

                                  By: /s/ RANJAN LAL
                                      ------------------------------------------
                                      Ranjan Lal, Managing Partner

<PAGE>   25

                                    EXHIBIT A

                AMENDED AND RESTATED CERTIFICATE OF INCORPORATION

<PAGE>   26

                               State of Delaware               PAGE 1

                        Office of the Secretary of State

     I, EDWARD J. FREEL, SECRETARY OF STATE OF THE STATE OF DELAWARE, DO HEREBY
CERTIFY THE ATTACHED IS A TRUE AND CORRECT COPY OF THE RESTATED CERTIFICATE OF
"ARRAY BIOPHARMA INC.", FILED IN THIS OFFICE ON THE THIRTY-FIRST DAY OF AUGUST,
A.D. 2000, AT 11:30 O'CLOCK A.M.

     A FILED COPY OF THIS CERTIFICATE HAS BEEN FORWARDED TO THE NEW CASTLE
COUNTY RECORDER OF DEEDS.

                                       /s/ EDWARD J. FREEL
                             [SEAL]    -----------------------------------
                                       Edward J. Freel, Secretary of State

2856233 8100                                       AUTHENTICATION: 0650953

001441765                                                    DATE: 08-31-00

<PAGE>   27

                                                           STATE OF DELAWARE
                                                          SECRETARY OF STATE
                                                      DEPARTMENT OF CORPORATIONS
                                                      FILED 11.30 AM 08/31/2000
                                                          001441765 - 2856233

                              AMENDED AND RESTATED
                         CERTIFICATE OF INCORPORATION OF
                              ARRAY BIOPHARMA INC.

                       (PURSUANT TO SECTIONS 242 AND 245)

     Array BioPharma Inc., a corporation organized and existing under and by
virtue of the General Corporation Law of the State of Delaware (the
"Corporation"), does hereby certify as follows for the purpose of amending and
restating its Certificate of Incorporation:

     1. The Corporation was originally incorporated under the same name, and the
original Certificate of Incorporation of the Corporation was filed with the
Secretary of State of the State of Delaware on February 6, 1998.

     2. The Board of Directors of the Corporation duly adopted resolutions
containing provisions of this Amended and Restated Certificate of Incorporation
of the Corporation, declaring such amendment and restatement to be advisable and
called for the approval of the stockholders of the Corporation to such amendment
and restatement in accordance with Sections 242 and 245 of the General
Corporation Law of the State of Delaware.

     3. That the holders of at least 66 2/3% of the outstanding shares of the
Corporation's Series A Preferred Stock voting as a single class, 66 2/3% of the
outstanding shares of the Corporation's Series B Preferred Stock voting as a
single class and 50% of the outstanding shares of the Corporation's Common Stock
and Preferred Stock voting as a single class, in each case acting by means of
written consent in lieu of a meeting pursuant to Section 228(a) of the General
Corporation Law of the State of Delaware, adopted and approved this Amended and
Restated Certificate of Incorporation in accordance with Sections 242 and 245 of
the General Corporation Law of the State of Delaware.

     4. That the text of the Corporation's Certificate of Incorporation as
heretofore amended and supplemented is hereby further amended and restated in
its entirety to read as follows:

                                   ARTICLE I
                                      NAME

         The name of the corporation is Array BioPharma Inc.

                                   ARTICLE II
                          REGISTERED OFFICE AND AGENT

         The address of its registered office in the State of Delaware is 1209
Orange Street, in the City of Wilmington, County of New Castle 19801. The name
of its registered agent at such address is The Corporation Trust Company.

                                       1
<PAGE>   28

                                   ARTICLE III
                               NATURE OF BUSINESS

          The nature of the business or purposes to be conducted or promoted is
to engage in any lawful act or activities for which corporations may be
organized under the General Corporation Law of the State of Delaware.

                                   ARTICLE IV
                              CAPITAL; SHAREHOLDERS

     4.1 Authorized Capital. The aggregate number of shares that the Corporation
shall have authority to issue is 20,225,000 shares of common stock, each having
a par value of $0.001 (the "Common Stock"), and 11,825,000 shares of preferred
stock, each having a par value of $0.001, 6,800,000 shares of which shall be
designated as Series A Preferred Stock, 3,300,000 shares of which shall be
designated as Series B Preferred Stock and 1,725,000 shares of which shall be
designated as Series C Preferred Stock. The Series A Preferred Stock, Series B
Preferred Stock and the Series C Preferred Stock is sometimes collectively
referred to herein as the "Preferred Stock."

     4.2 Relative Rights and Preferences. The designations, preferences and
rights of the shares of each class of stock which the Corporation is authorized
to issue, and the limitations thereof, are as set forth in the following
provisions of this Section 4.2:

          (a) Common Stock.

               (i) General. The dividend and liquidation rights of the holders
          of the Common Stock are junior to, subject to and qualified by the
          rights of the holders of the Preferred Stock.

               (ii) Dividends. Dividends may be declared and paid on the Common
          Stock from funds lawfully available therefor as and when determined by
          the Board of Directors, subject to any preferential dividend rights of
          any then-outstanding Preferred Stock.

               (iii) Liquidation. In the event of any liquidation, dissolution
          or winding-up of the Corporation, whether voluntary or involuntary,
          the holders of the Common Stock shall be entitled, out of the assets
          of the Corporation available for distribution to its shareholders,
          subject to any preferential rights of any then-outstanding Preferred
          Stock, to share ratably among themselves in proportion to the
          respective amounts that would otherwise be payable in respect of the
          shares

                                       2
<PAGE>   29

          held by them upon such distribution if all amounts payable on or with
          respect to such shares were paid in full.

               (iv) Voting. Each holder of Common Stock of record shall have one
          vote for each share of stock outstanding in his name and on the books
          of the Corporation except that, in the election of directors, he shall
          have the right to vote each such share for as many persons as there
          are directors to be elected. Cumulative voting shall not be allowed in
          the election of directors or for any other purpose.

          (b) Series Preferred Stock. The designations, dividend rights, voting
          powers, rights on liquidation and other preferences and relative,
          participating, optional or other special rights and the
          qualifications, limitations or restrictions of the shares of the
          series of Preferred Stock shall be as follows:

               (i) Certain Definitions. Unless the context otherwise requires,
          for purposes of Section 4.2(b), the terms defined in this Section
          4.2(b)(i) shall have the meanings herein specified (with terms defined
          in the singular having comparable meanings when used in the plural).

                    "Common Stock" shall mean the common stock, $0.001 par value
          per share, of the Corporation.

                    "Disposition Proceeds" shall have the meaning set forth in
          Section 4.2(b)(iii)(C).

                    "Equivalent Common Dividend" shall have the meaning set
          forth in Section 4.2(b)(ii).

                    "Liquidation Preferences" shall have the meaning set forth
          in Section 4.2(b)(iii)(C).

                    "Mandatory Conversion Date" shall have the meaning set forth
          in Section 4.2(b)(iv)(B).

                    "Preferred Stock" shall mean any authorized series of
          preferred stock of the Corporation, including, without limitation, the
          Series A Preferred Stock, the Series B Preferred Stock and the Series
          C Preferred Stock.

                    "Qualifying IPO" shall mean an underwritten public offering
          pursuant to an effective registration statement under the Securities
          Act of 1933 of shares of Common Stock, at a price per share of at
          least $8.00, and the aggregate

                                       3
<PAGE>   30

          gross proceeds of which equal or exceed $20,000,000 (before
          underwriting discounts and commissions).

                    "Required Consent" shall mean (i) the affirmative vote of
          the holders of at least 66 2/3% of the outstanding shares of Preferred
          Stock or a series of such Preferred Stock, as the case may be, taken
          at a duly called meeting of the holders of such Preferred Stock or
          series of such Preferred Stock; or (ii) the written consent of the
          holders of at least 66 2/3% of the outstanding shares of Preferred
          Stock or a series of such Preferred Stock, as the case may be.

                    "Series A Initial Purchase Price" shall mean $1.00 per share
          (adjusted for stock dividends, stock splits, reverse stock splits,
          combinations and the like).

                    "Series A Liquidation Preference" shall have the meaning set
          forth in Section 4.2(b)(iii)(C).

                    "Series A Preferred Stock" shall mean the Series A Preferred
          Stock, $0.001 par value per share, of the Corporation.

                    "Series B Initial Purchase Price" shall mean $2.50 per share
          (adjusted for stock dividends, stock splits, reverse stock splits,
          combinations and the like).

                    "Series B Liquidation Preference" shall have the meaning set
          forth in Section 4.2(b)(iii)(C).

                    "Series B Preferred Stock" shall mean the Series B Preferred
          Stock, $0.001 par value per share, of the Corporation.

                    "Series C Initial Purchase Price" shall mean $6.00 per share
          (adjusted for stock dividends, stock splits, reverse stock splits,
          combinations and the like).

                    "Series C Liquidation Preference" shall have the meaning set
          forth in Section 4.2(b)(iii)(C).

                    "Series C Preferred Stock" shall mean the Series C Preferred
          Stock, $0.001 par value per share, of the Corporation.

                    "Subordinate Stock" shall mean any class or series of
          capital stock of the Corporation, however designated, which is junior
          in right to the Preferred Stock, including without limitation the
          Common Stock and any other capital stock

                                       4
<PAGE>   31

          of the Corporation that is not entitled to receive (i) any dividends
          unless all dividends required to have been paid or declared and set
          apart for payment on the Preferred Stock shall have been so paid or
          declared and set apart for payment; or (ii) any assets upon
          liquidation, dissolution or winding up of the affairs of the
          Corporation until the Preferred Stock shall have received the entire
          amount to which such stock is entitled upon such liquidation,
          dissolution or winding up.

               (ii) Dividends. If at any time during which any shares of Series
          A Preferred Stock, Series B Preferred Stock or Series C Preferred
          Stock remain outstanding the Corporation declares, pays or sets apart
          for payment any dividend on the Common Stock, whether in cash,
          property or otherwise, each holder of shares of Series A Preferred
          Stock, Series B Preferred Stock or Series C Preferred Stock shall be
          entitled to receive the equivalent per share dividend (an "Equivalent
          Common Dividend"), when and as declared by the Corporation, based on
          the number of shares of Common Stock into which each share of
          Preferred Stock is convertible on the record date. For any Equivalent
          Common Dividend that is not paid in full when due, then on such due
          date such accrued and unpaid Equivalent Common Dividend shall be added
          to the Liquidation Preference of the Preferred Stock effective at such
          due date when such Equivalent Common Dividend was not paid. If any
          accrued and unpaid Equivalent Common Dividend is so added to the
          Liquidation Preference, such Liquidation Preference shall be reduced,
          effective on the date of payment, to the extent any accrued and unpaid
          Equivalent Common Dividend is subsequently paid.

               (iii) Distributions Upon Liquidation, Dissolution or Winding Up.

                    (A) The Corporation shall deliver to each holder of
               Preferred Stock notice of any Disposition (as defined in Section
               4.2(b)(iii)(B)) at least 90 days prior to such event, which
               notice shall state all material facts and common terms relating
               to such Disposition, including, without limitation, (1) the
               nature of such Disposition, including, without limitation, the
               amount, terms and conditions of payment to the holders of the
               Preferred Stock and the holders of Common Stock in connection
               with such Disposition; (2) the date on which such Disposition
               shall occur; and (3) the procedures that must be followed (and
               the latest date that such procedures must be completed) in order
               for such holder to effect a conversion of shares of Preferred
               Stock into shares of Common Stock, if such a conversion is so
               desired.

                    (B) The following events shall be considered a "Disposition"
               under this Section:

                         (1) any consolidation or merger of the Corporation with
                    or into any other corporation or other entity or person, or
                    any other

                                       5
<PAGE>   32

                    corporate reorganization, in which the stockholders of the
                    Corporation immediately prior to such consolidation, merger
                    or reorganization, own less than 50% of the Corporation's
                    voting power immediately after such consolidation, merger or
                    reorganization, or any transaction or series of related
                    transactions in which in excess of 50% of the Corporation's
                    voting power is transferred;

                         (2) a sale, lease or other disposition of all or
                    substantially all of the assets of the Corporation; or

                         (3) any voluntary or involuntary liquidation,
                    dissolution or other winding up of the affairs of the
                    Corporation.

                    (C) In the event of any such Disposition, before any payment
               or distribution shall be made to the holders of the Common Stock,
               the holders of Preferred Stock shall be entitled to be paid out
               of the Disposition Proceeds in cash, or, if the Corporation does
               not have sufficient cash on hand to pay such amounts, property of
               the Corporation at its fair market value as determined by the
               Board of Directors, an amount (the "Series A Liquidation
               Preference", the "Series B Liquidation Preference" and the
               "Series C Liquidation Preference") equal to either the Series A
               Initial Purchase Price, the Series B Initial Purchase Price or
               the Series C Initial Purchase Price, as appropriate, plus any
               accrued but unpaid dividends. If upon any such Disposition, the
               remaining assets of the Corporation available for distribution to
               its shareholders shall be insufficient to pay the holders of the
               Preferred Stock the full amount of their respective Liquidation
               Preferences, the holders of the Preferred Stock shall share
               ratably among themselves in any distribution of the remaining
               assets and funds of the Corporation in proportion to the
               respective amounts that would otherwise be payable in respect of
               the shares held by them upon such distribution if all amounts
               payable on or with respect to such shares were paid in full.

               (iv) Conversion Rights.

                    (A) Conversion at the Option of the Holder. The holders of
               the Preferred Stock shall have the right, at their option, to
               convert shares of Preferred Stock into shares of Common Stock of
               the Corporation at any time and from time to time on the
               following terms and conditions:

                         (1) Each share of Preferred Stock shall be converted at
                    the option of the holder thereof, without the payment of
                    additional

                                       6
<PAGE>   33

                    consideration, into such number of fully paid and
                    nonassessable shares of Common Stock as is determined by
                    dividing the Series A Initial Purchase Price, the Series B
                    Initial Purchase Price or the Series C Initial Purchase
                    Price, as applicable, by the Series A Conversion Rate, the
                    Series B Conversion Rate or the Series C Conversion Rate,
                    respectively, in effect at the time of conversion. For
                    purposes of this section, the "Series A Conversion Rate",
                    the "Series B Conversion Rate" and the "Series C Conversion
                    Rate" shall initially shall be equal to the Series A Initial
                    Purchase Price, Series B Initial Purchase Price and the
                    Series C Initial Purchase Price, respectively, and shall
                    each be subject to adjustment as provided in Section
                    4.2(b)(iv)(C)(2) below.

                         (2) The Corporation shall not issue, in connection with
                    the conversion of shares of Preferred Stock, certificates
                    for fractional shares, but in lieu thereof shall pay to any
                    person who would otherwise be entitled thereto an amount of
                    cash equal to such fraction multiplied by the fair value of
                    one share of Common Stock, as determined by the Board of
                    Directors, whose determination shall be conclusive.

                         (3) In order for any holder of shares of Preferred
                    Stock to convert the same into Common Stock, he shall
                    surrender the certificate or certificates therefor, duly
                    endorsed, at the office of the Corporation and shall give
                    written notice to the Corporation that he elects to convert
                    all or part of the shares represented by the certificate or
                    certificates and shall state in writing therein the name or
                    names in which he wishes the certificate or certificates for
                    Common Stock to be issued. The Corporation shall, as soon as
                    practicable thereafter, issue and deliver to such holder of
                    shares of Preferred Stock, or to his nominee or nominees,
                    certificates for the full number of shares of Common Stock
                    to which he shall be entitled as aforesaid. Shares of
                    Preferred Stock shall be deemed to have been converted as of
                    the date of the surrender of such shares for conversion as
                    provided above, and the person or persons entitled to
                    receive Common Stock issuable upon such conversion shall be
                    treated for all purposes as the record holder or holders of
                    such Common Stock on such date.

                         (4) If a holder converts shares of Preferred Stock, the
                    Corporation shall pay any documentary , stamp or similar
                    issue or transfer tax due on the issue of shares of Common
                    Stock upon the conversion; provided, however, that the
                    holder shall pay any such

                                       7
<PAGE>   34

                    tax that is due because the shares are issued in a name
                    other than the holder's name pursuant to Section
                    4.2(b)(iv)(A)(3).

                    (B) Mandatory Conversion. Subject to the adjustments set
               forth in Section 4.2(b)(iv)(C), each share of Preferred Stock
               shall be converted automatically into shares of the Corporation's
               Common Stock at the Series A Conversion Rate, Series B Conversion
               Rate or Series C Conversion Rate, as applicable, on the date a
               Qualifying IPO is consummated (the "Mandatory Conversion Date").
               At least 60 days prior to the Mandatory Conversion Date, the
               Corporation shall (1) notify all holders of the Preferred Stock
               of such event; (2) demand that all shares representing the
               Preferred Stock be returned to the Corporation's offices or to
               the designated transfer agent; and (3) pay any transfer or
               similar tax with respect to the conversion, if any. As soon as
               practical but in any event within 30 days after the Mandatory
               Conversion Date, the Corporation shall deliver a certificate to
               and in the name of the holder of the Preferred Stock for the
               number of shares of Common Stock issuable upon the conversion and
               a check in an amount calculated in accordance with Section
               4.2(b)(iv)(A)(2) for any fractional shares, if any, for the
               shares of Preferred Stock represented by the certificate. The
               name of the person in which the Preferred Stock was issued shall
               be treated as the stockholder of record of the Common Stock in
               which the Preferred Stock was converted on and after the
               Mandatory Conversion Date. Adjustment (or cash payment, if
               applicable) shall be made for accrued and previously declared and
               unpaid dividends, as of the Mandatory Conversion Date, on shares
               of Preferred Stock converted pursuant to this Section
               4.2(b)(iv)(B). Upon such conversion, the rights of the holders of
               Preferred Stock with respect to the shares of Preferred Stock so
               converted shall cease.

                    (C) Certain Matters With Respect to Conversion.

                         (1) The Corporation has reserved and shall continue to
                    reserve out of its authorized but unissued Common Stock or
                    its Common Stock held in treasury enough shares of Common
                    Stock to permit the conversion of the Preferred Stock in
                    full. All shares of Common Stock that may be issued upon
                    conversion of Preferred Stock shall be duly authorized,
                    validly issued, fully paid and nonassessable.

                         (2) The Series A Conversion Rate, Series B Conversion
                    Rate and Series C Conversion Rate shall be subject to
                    adjustment as follows:

                                       8
<PAGE>   35

                         (a) In case the Corporation shall (i) pay a dividend or
                    make a distribution on its Common Stock in shares of Common
                    Stock of the Corporation, (ii) subdivide or split its
                    outstanding Common Stock, or (iii) combine the outstanding
                    Common Stock into a smaller number of shares, the Series A
                    Conversion Rate, Series B Conversion Rate and Series C
                    Conversion Rate following the effective date of such event
                    shall be equal to the product of the Series A Conversion
                    Rate, Series B Conversion Rate or Series C Conversion Rate,
                    respectively, in effect immediately prior to such adjustment
                    multiplied by a fraction, the denominator of which is the
                    number of shares of Common Stock outstanding immediately
                    after such event and the numerator of which is the number of
                    shares outstanding immediately prior to such event.

                         (b) In the event the Corporation at any time or from
                    time to time shall make or issue, or fix a record date for
                    the determination of holders of Common Stock entitled to
                    receive a dividend or other distribution payable in
                    securities of the Corporation other than shares of Common
                    Stock, then and in each such event provision shall be made
                    so that the holders of Preferred Stock shall receive upon
                    conversion thereof in addition to the number of shares of
                    Common Stock receivable thereupon, the amount of securities
                    of the Corporation that they each would have received had
                    the Preferred Stock been converted into Common Stock on the
                    date of such event and had they each thereafter, during the
                    period from the date of such event to and including the
                    conversion date, retained such securities receivable by them
                    as aforesaid during such period, giving application to all
                    adjustments called for during such period under this section
                    with respect to the rights of the holders of Preferred
                    Stock; provided, however, that no such adjustment shall be
                    made if the holders of Preferred Stock simultaneously
                    receive a dividend or other distribution of such securities
                    as they would have received if all outstanding shares of
                    Preferred Stock had been converted into Common Stock on the
                    date of such event.

                         (c) If Common Stock issuable upon the conversion of
                    Preferred Stock shall be changed into the same or a
                    different number of shares of any class or classes of stock,
                    whether by capital reorganization, reclassification, or
                    otherwise (other than a subdivision or combination of shares
                    or stock dividend provided for above, or a reorganization,
                    merger, consolidation, or sale of assets provided for
                    below), then and in each such event the holder of each such
                    share of Preferred Stock shall have the right thereafter

                                       9
<PAGE>   36

                    to convert such share into the kind and amount of shares of
                    stock and other securities and property receivable upon such
                    reorganization, reclassification, or other change, by
                    holders of the number of shares of Common Stock into which
                    such share of Preferred Stock might have been converted
                    immediately prior to such reorganization, reclassification,
                    or change, all subject to further adjustment as provided
                    herein.

                         (d) Adjustments to the Series A Conversion Rate, Series
                    B Conversion Rate and Series C Conversion Rate shall also be
                    made for certain dilutive issuances of additional shares of
                    capital stock by the Corporation as set forth in this
                    Section 4.2(b)(iv)(C)(2)(d).

                         (i)  Special Definitions. For purposes of this Section
                              4.2(b)(iv)(C)(2)(d), the following definitions
                              shall apply:

                              (A) "Option" means rights, options, warrants or
                              other securities convertible into or exchangeable
                              or exercisable for shares of Common Stock or
                              Preferred Stock.

                              (B) "Additional Shares of Stock" (i) with respect
                              to the Series A Preferred Stock, all shares of
                              Common Stock or Preferred Stock issued by the
                              Corporation after the date that shares of Series A
                              Preferred Stock are first issued by the
                              Corporation (the "Series A Initial Issue Date")
                              for which the consideration per share (determined
                              pursuant to Section 4.2(b)(iv)(C)(2)(d)(iii)) is
                              less than the Series A Conversion Rate in effect
                              on the date of, and immediately prior to, the
                              issuance of such Additional Shares of Stock; (ii)
                              with respect to the Series B Preferred Stock, all
                              shares of Common Stock or Preferred Stock issued
                              by the Corporation after the date that shares of
                              Series B Preferred Stock are first issued by the
                              Corporation (the "Series B Initial Issue Date")
                              for which the consideration per share (determined
                              pursuant to Section 4.2(b)(iv)(C)(2)(d)(iii)) is
                              less than the Series B Conversion Rate in effect
                              on the date of, and immediately prior to, the
                              issuance of such Additional Shares of Stock;

                                       10
<PAGE>   37

                              (iii) with respect to the Series C Preferred
                              Stock, all shares of Common Stock or Preferred
                              Stock issued by the Corporation after the date
                              that shares of Series C Preferred Stock are first
                              issued by the Corporation (the "Series C Initial
                              Issue Date") for which the consideration per share
                              (determined pursuant to Section
                              4.2(b)(iv)(C)(2)(d)(iii)) is less than the Series
                              C Conversion Rate in effect on the date of, and
                              immediately prior to, the issuance of such
                              Additional Shares of Stock, provided, however that
                              in the case of any series of Preferred Stock, not
                              including any shares of Common Stock or Preferred
                              Stock issued or issuable:

                                   (I) upon exercise of any Options outstanding
                                   on the Series C Initial Issue Date; provided,
                                   however that if the Corporation, after the
                                   Series C Initial Issue Date, amends the
                                   exercise price or the number of shares
                                   covered by any Options outstanding on the
                                   Series C Initial Issue Date, then such
                                   Options, as so amended, shall be deemed to
                                   have been issued after the Series C Initial
                                   Issue Date;

                                   (II) by reason of a dividend, stock split,
                                   split-up or other distribution on shares of
                                   Common Stock that is covered by Section
                                   4.2(b)(iv)(C)(2)(b) or (c) above;

                                   (III) upon exercise of Options granted to
                                   employees or directors of, or consultants to,
                                   the Corporation pursuant to a valid option
                                   plan adopted by the Corporation;

                                   (IV) to employees or directors of, or
                                   consultants to, the Corporation pursuant to a
                                   valid stock purchase plan adopted by the
                                   Corporation; or

                                   (V) upon exercise of warrants or other
                                   securities convertible into Common or
                                   Preferred Stock issued in connection with a
                                   credit facility, but not to exceed an
                                   aggregate

                                       11
<PAGE>   38

                                   of $200,000 in value (as determined by the
                                   exercise price) in any six month period.

                         (ii) Adjustment of Conversion Rates Upon Issuance of
                              Additional Shares of Stock. In the event the
                              Corporation shall at any time issue Additional
                              Shares of Stock with respect to the Series A
                              Preferred Stock, the Series B Preferred Stock or
                              the Series C Preferred Stock, then and in such
                              event, such Series A Conversion Rate, Series B
                              Conversion Rate or Series C Conversion Rate, as
                              applicable, shall be reduced, concurrently with
                              such issuance, to a price (calculated to the
                              nearest cent) determined by multiplying the Series
                              A Conversion Rate, the Series B Conversion Rate or
                              Series C Conversion Rate, as applicable, then in
                              effect by a fraction:

                              (A) the numerator of which shall be (1) the number
                              of shares of Common Stock outstanding immediately
                              prior to such issue plus (2) the number of shares
                              of Common Stock which the aggregate consideration
                              received or to be received by the Corporation for
                              the total number of Additional Shares of Stock so
                              issued would purchase at such Series A Conversion
                              Rate, Series B Conversion Rate or Series C
                              Conversion Rate, as applicable; and

                              (B) the denominator of which shall be the number
                              of shares of Common Stock outstanding immediately
                              prior to such issue plus the number of such
                              Additional Shares of Stock so issued.

                        (iii) Determination of Consideration. For purposes of
                              this Section 4.2(b)(iv)(C)(3)(d)(iii), the
                              consideration received by the Corporation for the
                              issue of any Additional Shares of Stock shall be
                              computed as follows:

                              (A) in case of the issuance of shares of Common
                              Stock for cash, the consideration shall be the
                              amount of such cash, provided that in no case
                              shall any deduction be made for any commissions,

                                       12
<PAGE>   39

                              discounts or other expenses incurred by the
                              Corporation for any underwriting of the issue or
                              otherwise in connection therewith;

                              (B) in the case of the issuance of shares of
                              Common Stock for a consideration in whole or in
                              part other than cash, the consideration other than
                              cash shall be deemed to be the fair market value
                              thereof as determined by the Board of Directors of
                              the Corporation in its reasonable judgment
                              exercised in good faith (irrespective of the
                              accounting treatment thereof); and

                              (C) in the case of the issuance of Options, the
                              aggregate consideration received therefor shall be
                              deemed to be the consideration received by the
                              Corporation for the issuance of such Options plus
                              the additional minimum consideration, if any, to
                              be received by the Corporation upon the conversion
                              or exchange or exercise thereof (the consideration
                              in each case to be determined in the same manner
                              as provided in clauses (i) and (ii) of this
                              Section).

                    (3) Whenever the number of shares of Common Stock into which
                    any share of Preferred Stock is convertible is adjusted, the
                    Corporation shall promptly mail to holders of the affected
                    Preferred Stock, first class, postage prepaid, a notice of
                    the adjustment. The Corporation shall file with the transfer
                    agent, if any, for the Preferred Stock a certificate from
                    the Corporation's independent public accountants briefly
                    stating the facts requiring the adjustment and the manner of
                    computing it. Subject to Section 4.2(b)(iv)(C)(9) below, the
                    certificate shall be conclusive evidence that the adjustment
                    is correct.

                    (4) The adjustments herein provided for shall be made
                    successively when the event giving rise to such adjustment
                    occurs and shall become effective immediately following the
                    record date for any event for which a record date is
                    designated and on the effective date for any other event.

                    (5) Shares of Preferred Stock that have been converted as
                    provided herein shall revert to the status of authorized but
                    unissued shares of Preferred Stock.

                                       13
<PAGE>   40

                    (6) For purposes of any computation of the number of shares
                    of Common Stock outstanding, such computation shall be made
                    assuming conversion of all then outstanding shares of
                    Preferred Stock and all outstanding currently exercisable
                    warrants and vested options.

                    (7) No adjustment in the number of shares of Common Stock
                    into which each share of Preferred Stock is convertible need
                    be made unless the adjustment would require an increase of
                    at least one-half of one percent (.5%) in the number of
                    shares of Common Stock into which each share of Preferred
                    Stock is convertible. Any adjustments that are not made
                    shall be carried forward and taken into account in any
                    subsequent adjustment. All calculations under this Section
                    4.2(b)(iv)(C) shall be made to the nearest cent or to the
                    nearest 1/100th of a share, as the case may be.

                    (8) In any case in which this Section 4.2(b)(iv)(C) shall
                    require that an adjustment as a result of any event become
                    effective from and after a record date, the Corporation may
                    elect to defer until after the occurrence of such event (a)
                    the issuance to the holder of any shares of Preferred Stock
                    converted after such record date and before the occurrence
                    of such event of the additional shares of Common Stock
                    issuable upon such conversion over and above the shares
                    issuable immediately prior to adjustment; and (b ) the
                    delivery of a check for any remaining fractional shares as
                    provided in Section 4.2(b)(iv)(A)(2) above.

                    (9) Except as provided in the immediately following
                    sentence, any determination that the Corporation or its
                    Board of Directors must make pursuant to this Section
                    4.2(b)(iv)(C) shall be conclusive. Whenever the Corporation
                    or its Board of Directors shall be required to make a
                    determination under this Section 4.2(b)(iv)(C), such
                    determination shall be made in good faith and may be
                    challenged in good faith by the holders of a majority of the
                    affected Series A Preferred Stock, Series B Preferred Stock
                    and/or Series C Preferred Stock, as applicable, and any
                    dispute shall be resolved promptly (and in no event later
                    than 90 days after any challenge), at the Corporation's
                    expense, by an investment banking firm of recognized
                    national standing selected by the Corporation and acceptable
                    to such holders of Series A Preferred Stock, Series B
                    Preferred Stock and/or Series C Preferred Stock, as
                    applicable. Any such determination shall be deemed approved
                    if the requisite holders have not notified the Corporation
                    of any challenge within

                                       14
<PAGE>   41

                    30 days after receiving notice (including a statement in
                    reasonable detail of the bases therefor) of such
                    determination.

               (v) Voting Rights.

                    (A) Except as otherwise set forth in this Section 4.2(b)(v)
               or as otherwise required by law, each share of Preferred Stock
               issued and outstanding shall have the right to vote on all
               matters presented to the holders of the Common Stock for vote in
               the number of votes equal at any time to the number of shares of
               Common Stock into which each share of Preferred Stock would then
               be convertible, and the holders of the Preferred Stock shall vote
               with the holders of the Common Stock as a single class.

                    (B) In addition to any vote or consent of shareholders or
               directors required by law or this Amended and Restated
               Certificate of Incorporation, so long as any originally issued
               Series A Preferred Stock, Series B Preferred Stock or Series C
               Preferred Stock remains outstanding, the Required Consent of the
               holders of the Series A Preferred Stock, Series B Preferred Stock
               and/or Series C Preferred Stock shall be necessary for effecting,
               validating or permitting:

                         (1) any amendment, alteration or repeal of any of the
                    provisions of the Corporation's Amended and Restated
                    Certificate of Incorporation or the Bylaws affecting the
                    rights, powers and preferences of the Series A Preferred
                    Stock, Series B Preferred Stock or Series C Preferred Stock,
                    as applicable, provided, however that the Required Consent
                    for this subparagraph (1) shall be of the holders of Series
                    A Preferred Stock, Series B Preferred Stock or Series C
                    Preferred Stock, voting as separate classes and only if such
                    series is affected; or

                         (2) any consolidation or merger of the Corporation with
                    or into any other corporation, or any other corporate
                    reorganization, in which the stockholders of the Corporation
                    immediately prior to such consolidation, merger or
                    reorganization, own less than 50% of the Corporation's
                    voting power immediately after such consolidation, merger or
                    reorganization; any transaction or series of related
                    transactions in which excess of 50% of the Corporation's
                    voting power is transferred; any reclassification or
                    recapitalization of any capital stock of the Corporation;
                    any dissolution, liquidation, or winding up of the
                    Corporation; or any sale of more than 50% of the assets of
                    the Corporation, or any agreement to become so obligated;
                    provided, however that the Required Consent for this
                    subparagraph (2) shall be of the holders

                                       15
<PAGE>   42

                    of Series A Preferred Stock, Series B Preferred Stock and
                    Series C Preferred Stock, voting together as a single class.

                    (C) The rights of the holders of the Preferred Stock set
               forth in this Section 4.2(b)(v) may be exercised either at a
               special meeting of the holders of each series of Preferred Stock,
               called as hereinafter provided, or at any annual meeting of
               stockholders held for the purpose of electing directors, and
               thereafter at such annual meetings, special meetings or by the
               written consent of the holders of Preferred Stock, as applicable.

                    (D) A special meeting of the holders of Preferred Stock for
               purposes of voting on matters with respect to which the holders
               of such shares are entitled to vote as a class may be called by
               the Secretary of the Corporation or by a holder of Preferred
               Stock designated in writing by the holders of record of 10% of
               the shares of such series of Preferred Stock then outstanding.
               Such meeting may be called at the expense of the Corporation by
               any such person. At any meeting of the holders of each series of
               Preferred Stock, the presence in person or by proxy of the
               holders of a majority of the shares of such series of Preferred
               Stock then outstanding shall constitute a quorum of the such
               series of Preferred Stock.

               (vi) Miscellaneous.

                    (A) Headings of Sections. The headings of the various
               subdivisions hereof are for convenience of reference only and
               shall not affect the interpretation of any of the provisions
               hereof.

                    (B) Severability of Provisions. If any voting powers,
               preferences and relative, participating, optional and other
               special rights of the Preferred Stock and qualifications,
               limitations and restrictions thereof set forth herein (as may be
               amended from time to time) is invalid, unlawful or incapable of
               being enforced by reason of any rule of law or public policy, all
               other voting powers, preferences and relative, participating,
               optional and other special rights of Preferred Stock and
               qualifications, limitations and restrictions thereof set forth
               herein (as so amended) that can be given effect without the
               invalid, unlawful or unenforceable voting powers, preferences and
               relative, participating, optional and other special rights of
               Preferred Stock and qualifications, limitations and restrictions
               thereof shall, nevertheless, remain in full force and effect, and
               no voting powers, preferences and relative, participating,
               optional or other special rights of Preferred Stock and
               qualifications, limitations and restrictions thereof herein set
               forth shall be deemed dependent upon any other such voting
               powers, preferences and relative,

                                       16
<PAGE>   43

               participating, optional or other special rights of Preferred
               Stock and qualifications, limitations and restrictions thereof
               unless so expressed herein.

(c) Other Series of Preferred Stock. Subject to the approval requirements
contained herein, the Board of Directors is hereby expressly authorized by
resolution from time to time adopted providing for the issuance of preferred
stock, to fix and state the designations, powers, preferences and relative,
optional and other special rights of the shares of each series of preferred
stock, and the qualifications, limitations and restrictions thereof, including
(but without limiting the generality of the foregoing) any of the following with
respect to which the Board of Directors shall determine to make effective
provisions:

          (i) the distinctive name and serial designation;

          (ii) the dividend payment dates;

          (iii) the rate or rates at which dividends if any shall be paid;

          (iv) whether dividends are to be cumulative or noncumulative, and any
     preferential or other special rights with respect to the payment of
     dividends;

          (v) whether any series shall be redeemable and if so, the terms,
     conditions and manner of redemption, and the redemption price or prices;

          (vi) he rights of any series on voluntary or involuntary liquidation,
     dissolution or winding up, including the amounts or amounts of preferential
     or other payments to which any series is entitled over any other series or
     over the common stock;

          (vii) any sinking fund or other retirement provisions and the extent
     to which the charges therefor are to have priority over the payment of
     dividends on or the making of sinking fund or other like retirement
     provisions for shares of any other series or over dividends on the common
     stock;

          (viii) the number of shares of such series;

          (ix) the voting rights, if any, for such series; and

          (x) the conversion rights, if any, for such series.

     Unless otherwise provided in the resolution of the Board of Directors
providing for the issue thereof, the shares of any series of preferred stock
which shall be issued and thereafter

                                       17
<PAGE>   44

acquired by the Corporation through purchase, redemption, conversion or
otherwise may by resolution of the Board of Directors be returned to the status
of authorized but unissued preferred stock of the same or other series. Unless
otherwise provided in the resolution of the Board of Directors providing for the
issue thereof, the number of authorized shares of stock of any such series may
be increased or decreased (but not below the number of shares thereof then
outstanding) by resolution by the Board of Directors. In case the number of
shares of any such series of preferred stock shall be decreased, the shares
representing such decrease shall, unless otherwise provided in the resolution of
the Board of Directors providing for the issuance thereof, resume the status of
authorized but unissued preferred stock, undesignated as to series.

                                    ARTICLE V

                             LIMITATION ON LIABILITY

     To the fullest extent permitted by the General Corporation Law of Delaware,
as the same exists or may hereafter be amended, a director of the Corporation
shall not be liable to the Corporation or its stockholders for monetary damages
for breach of fiduciary duty as a director. Any repeal or modification of this
Article by the stockholders of the Corporation shall be prospective only and
shall not adversely affect any right or protection of a director of the
Corporation existing at the time of such repeal or modification.

                                   ARTICLE VI

                                 INDEMNIFICATION

     Each person who is or was a director or officer of the Corporation, and
each such person who is or was serving at the request of the Corporation as a
director or officer of another Corporation, or in a similar capacity of a
partnership, joint venture, trust or other enterprise, including service with
respect to employee benefit plans maintained or sponsored by the Corporation
(including the heirs, executors, administrators and estate of such person) shall
be indemnified by the Corporation, in accordance with the procedures specified
in the Bylaws of the Corporation, to the fullest extent permitted from time to
time by the General Corporation Law of the State of Delaware. The Corporation
may, to the extent authorized from time to time by the Board of Directors, grant
rights to indemnification and to the advancement of expenses to any employee or
agent of the Corporation to the fullest extent of the provisions of this Article
with respect to the indemnification and advancement of expenses of directors and
officers of the Corporation, without limiting the generality of the foregoing,
the Corporation may enter into one or more agreements with any person that
provide for indemnification and advancement of expenses greater or different
than that provided in this Article. No amendment or repeal of this Article shall
adversely affect any right or protection existing under or pursuant to this
Article immediately before the amendment or repeal.

                                       18
<PAGE>   45

                                   ARTICLE VII

                              ELECTION OF DIRECTORS

     Elections of directors need not be by written ballot unless the bylaws of
the Corporation so provide.

                                  ARTICLE VIII

                              AMENDMENTS TO BYLAWS

     The Board of Directors of the Corporation is expressly authorized to make,
alter or repeal the bylaws of the Corporation.

                            [signature page follows]

                                       19
<PAGE>   46

     IN WITNESS WHEREOF, this Amended and Restated Certificate of Incorporation
of the Corporation has been executed this 31st day of August 2000.

                                      ARRAY BIOPHARMA INC.

                                      By: /s/ ROBERT CONWAY
                                          --------------------------------------
                                          Robert Conway, Chief Executive Officer

                                       20
<PAGE>   47
                                    EXHIBIT B

<TABLE>
<CAPTION>
        PURCHASERS                                                SHARES
        ----------                                                ------
<S>                                                               <C>
             ARCH Venture Fund III, L.P.                               204,779
             Frazier Healthcare II, L.P.                                16,667
             Boulder Ventures II, L.P.                                 136,587
             Boulder Ventures II, (Annex) L.P.                          20,410
             Falcon Technology Partners, L.P.                          156,997
             Rovent II Limited Partnership                              50,000
             Mitsui & Co. (U.S.A.), Inc.                                34,130
             David Snitman, Ph.D.                                      266,667
             Anthony D. Piscopio, Ph.D.                                  1,667
             K.C. Nicolaou, Ph.D.                                       50,000
             Frank A. Bonsal, Jr.                                        5,834
             The Caruthers Family, L.L.C.                               33,936
             Michael Carruthers                                          3,332
             Christopher D. Ozeroff                                     13,621
             William R. Roberts                                          1,207
             Kirby L. Cramer                                            83,333
             Joseph Lefkoff                                              4,166
             Mosaix Ventures, LP                                       166,667
             Vector Later-Stage Equity Fund II, L.P.                   104,167
             Vector Later-Stage Equity Fund II (Q.P.), L.P.            312,500
             TOTAL:                                                  1,666,667
</TABLE>

<PAGE>   48

                                    EXHIBIT C

                               DISCLOSURE SCHEDULE

         General - The Array BioPharma Inc. unaudited financial statements for
the year ended June 30, 2000 are included by reference to all applicable
representations.

         3.7 Material Contracts - (a) From time to time, Array BioPharma Inc.
purchases analytical instruments and other capital equipment, generally pursuant
to a purchase order. Such purchase orders have occasionally been in excess of
$300,000, and are periodically in excess of $30,000. Array BioPharma Inc. has
recently ordered various analytical instruments for on-going operations and
expansion at a cost of approximately $1,200,000. Array BioPharma Inc. licenses
an assortment of scientific and business software, the license fees for, which
are currently as high as $80,000 per year.

         Significant Sales Agreements with future commitments:

<TABLE>
<CAPTION>
Customer                   Date         Type of Agreement
--------                   ----         -----------------
<S>                        <C>          <C>
Eli Lilly                  4/00         Lead Optimization
ICOS                       8/00         Lead Optimization
CellTech                   6/99         Diversity Library
Tularik                    5/99         Diversity Library
Merck                     Various       Custom Libraries
DuPont                     8/00         Diversity Library
ICOS                       1/00         Process Scale-up
Neurocrine                 10/99        Custom Library
Various Other             Various       Building Blocks & Custom
                                        Synthesis or Libraries
</TABLE>

         Leases were entered into in July 1998, and April 1999 by and between
Amgen Inc. and Array BioPharma Inc. with a term of three years from the earlier
date for the premises located at 1885 33rd Street, Boulder Colorado and
providing for monthly rental payments of approximately $47,000 (triple net). A
building lease was entered into for a facility in Longmont Co. located at 2620
Trade Centre Avenue in February 2000 by and between Pratt Management Co. and
Array BioPharma with a term expiring May 2005 and monthly rental payments of
approximately $23,000 (triple net).

         Agreements with a laboratory cabinet manufacturer, a mechanical
contractor and a general contractor were entered into in April 2000 for the
purpose of providing hoods, cabinets, and improvements to the Longmont facility
in the amount of approximately $3,000,000.

         Software license agreement entered into in June of 1998, by and between
Tripos Inc. and Array BioPharma Inc. with a term of three years and providing
for yearly payments of approximately $80,000.

<PAGE>   49

         From time to time, Array BioPharma Inc. has had, in the normal course
of business negotiations, informal and preliminary discussions with
representatives of other corporations regarding the potential for various kinds
of business collaborations, including the possibility of acquisition of an
equity interest in Array BioPharma Inc.

         Array has agreed to provide a fellowship to Scripps in the amount of
$40,000.

         3.8 Obligations to Related Parties - Array BioPharma Inc. has loaned
the following amounts to certain of its executive officers. All of the loans
were made in May 1998 and are evidenced by promissory notes that bear simple
interest at 6% per annum. Principal and interest is due four years from the date
the loan was made. There are no periodic interest payments required.

             Kevin Koch - $100,000
             KC Nicolaou - $125,000
             Anthony Piscopio - $125,000

         3.9 Assets - Leases were entered into in July 1998, and April 1999 by
and between Amgen Inc. and Array BioPharma Inc. with a term of three years from
the earlier date for the premises located at 1885 33rd Street, Boulder Colorado
and providing for monthly rental payments of approximately $47,000 (triple net).
A building lease was entered into for a facility in Longmont Co. located at 2620
Trade Centre Avenue in February 2000 by and between Pratt Management Co. and
Array BioPharma with a term expiring May 2005 and monthly rental payments of
approximately $23,000 (triple net).

         Nearly all of Array BioPharma Inc.'s capitalized equipment is pledged
as collateral (UCC documents filed) for a combined equipment lease line of
$7,500,000 through Silicon Valley Bank and Leasing Technologies, Inc.

         3.10 Intellectual Property - Array BioPharma Inc. has a federal TM
application pending.

         3.14 Employees and Consultants - Array BioPharma Inc. has entered into
employment agreements each with a term of 2 years and that continue for one year
terms from year to year with the following individuals in the respective
capacity:

              Robert Conway (CEO) October 1999
              Kevin Koch (President) July 1998(1)
              David Snitman (Chief Operating Officer) July 1998(1)
              Anthony Piscopio (Vice President of Chemistry) July 1998(1)
              John Josey (Director) July 1998(1)
              Larry Burgess (Director) July 1998(l)

              (1) indicated agreements amended and renewed effective July 2000.

<PAGE>   50

         As of the date hereof, Array BioPharma Inc. has entered into
negotiations regarding employment agreements or amended employment agreements,
as the case may be, with the following people: Michael Carruthers (CFO); Joanna
Money (Director); Kevin Koch (President); David Snitman (Chief Operating
Officer); Anthony Piscopio (Vice President of Chemistry); John Josey
(Director); and Larry Burgess (Director).

         3.15 Employee Benefit Matters - Array BioPharma Inc. maintains a
401(k) savings Plan which has the ability to match certain employee
contributions. Beginning August 2000, Array BioPharma Inc. began a match of 50%
of the employee's contribution applied to the first 4% of pay contributed by the
employee.

         Array BioPharma Inc. provides a health insurance program requiring
nominal employee contributions for payment of premium. This Plan is partially
self-insured by Array BioPharma Inc. with aggregate and specific stop loss
insurance.

         3.19 Environmental Matters - Array BioPharma Inc. estimates that it
will continue to incur expenditures of approximately $30,000 to $70,000 per year
related to compliance with environmental and occupational health and safety
laws.

<PAGE>   51

                                   EXHIBIT D

                               AMENDMENT NO. 1 TO
                 AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT

<PAGE>   52

                               AMENDMENT NO. 1 TO
                 AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT

         This Amendment No. 1 to Amended and Restated Investors Rights Agreement
(this "Amendment") is made and entered into as of the 31st day of August, 2000,
by and among Array BioPharma Inc., a Delaware corporation (the "Company"), and
each of those persons and entities whose names are set forth under the heading
"Investors" or "Common Stockholders" on the signature page attached hereto,

                                    RECITALS

A.       The Company, certain of the Investors and the Common Stockholders
         previously entered into that certain Amended and Restated Investor
         Rights Agreement, dated as of November 16, 1999 (the "Investor Rights
         Agreement").

B.       The Company, certain Investors and the Common Stockholders have entered
         into that certain Series C Preferred Stock Purchase Agreement, dated of
         even date herewith (the "Purchase Agreement"), pursuant to which the
         Company will issue and sell, and the Investors will purchase, certain
         shares of the Company's Series C Preferred Stock (the "Stock").

C.       As a condition to the closing of the purchase of the Stock under the
         Purchase Agreement, the Company, the Investors and the Common
         Stockholders desire to amend the Investor Rights Agreement as provided
         herein.

         Now, Therefore, in consideration of the premises and for other good and
valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, the parties hereto agree to amend the Investor Rights Agreement as
follows:

                                   AMENDMENTS

1. The following definitions in Section 1 of the Investor Rights Agreement shall
be amended in their entirety to read as follows:

         (j) "Preferred Stock" shall mean any series of preferred stock of the
         Company including, without limitation, Series A Preferred, Series B
         Preferred or Series C Preferred.

         (s) "Shareholders Agreement" shall mean that certain Amended and
         Restated Shareholders Agreement dated as of November 16, 1999, as
         amended, by and among the Company and those certain holders of the
         Company's outstanding capital stock identified therein.

<PAGE>   53

2. The following new definition shall be added as Section 1(r) of the Investor
Rights Agreement:

           (r) "Series C Preferred Stock" shall mean the Series C Preferred
Stock, $.001 par value per share, of the Company, or any other capital stock of
the Company into which such stock is reclassified or reconstituted, or any
securities convertible into, or exchangeable or exercisable for, any of the
foregoing, in each case, at any time outstanding.

3. Section 3.1 of the Investor Rights Agreement shall be amended in its entirety
to read as follows:

         SECTION 3. OTHER COVENANTS OF THE COMPANY

                  The Company shall comply with the following covenants until
         the conversion of Investors' Series A Preferred Stock, Series B
         Preferred Stock and Series C Preferred Stock into Common Stock:

                  3.1 SIGNIFICANT TRANSACTIONS. In addition to any vote or
         consent of shareholders or directors required by law or the Company's
         Amended and Restated Certificate of Incorporation (the "Certificate"),
         so long as any originally issued Preferred Stock remains outstanding,
         the Required Consent of the Series A Preferred Stock, Series B
         Preferred Stock and Series C Preferred Stock, voting as separate
         classes for the transaction described in Section 3.1(a) and together as
         a single class for the transactions described in Section 3.1(b), either
         in writing without a meeting or by vote at any meeting called for the
         purpose, shall be necessary for effecting, validating or permitting:

                  (a) any amendment, alteration or repeal of any of (i) the
         provisions of the Certificate or the Bylaws of the Company affecting
         the rights, powers and preferences of the Series A Preferred Stock,
         Series B Preferred Stock or Series C Preferred Stock, as applicable, or
         (ii) the provisions of Article IV of the Certificate; or

                  (b) any consolidation or merger of the Company with or into
         any other corporation, or any other corporate reorganization, in which
         the stockholders of the Company immediately prior to such
         consolidation, merger or reorganization, own less than 50% of the
         Company's voting power immediately after such consolidation, merger or
         reorganization; any transaction or series of related transactions in
         which excess of 50% of the Company's voting power is transferred; any
         reclassification or recapitalization of any capital stock of the
         Company; any dissolution, liquidation, or winding up of the Company; or
         any sale of more than 50% of the assets of the Company, or any
         agreement to become so obligated.

                                  MISCELLANEOUS

1. Interpretation. Except as expressly amended by this Amendment, the Investor
Rights Agreement shall remain in full force and effect without change.

<PAGE>   54

2. Counterparts. This Amendment may be executed in any number of counterparts,
each of which when executed and delivered shall be an original, but all of which
together shall constitute one and the same instrument.

3. Effective Time. This Amendment shall be effective following its execution by
the holders of at least 66-2/3% of the outstanding shares held by the Holders
(as defined in the Investor Rights Agreement) and at least a majority of the
Common Stockholders, in accordance with Section 4.1 of the Investor Rights
Agreement.

4. Additional Investors. Each party who purchases Stock pursuant to the Purchase
Agreement agrees to be bound by the terms of the Investor Rights Agreement and
shall be deemed an additional "Investor" for all purposes thereunder.

                            [signature pages follow]

<PAGE>   55

                                   EXHIBIT E

                               AMENDMENT NO. 2 TO
                  AMENDED AND RESTATED SHAREHOLDERS AGREEMENT

<PAGE>   56

                               AMENDMENT NO. 2 TO
                   AMENDED AND RESTATED SHAREHOLDERS AGREEMENT

         This Amendment No. 2 to Amended and Restated Shareholders Agreement
(this "Amendment ") is entered into as of the 31st day of August, 2000, by and
among Array BioPharma Inc., a Delaware corporation (the "Company") and each of
those persons listed on the signature pages hereto as either "Investors",
"Founders" or "Holders ".

                                    RECITALS

         A.       The Company, Founders and certain Investors and Holders
                  previously entered into that certain Amended and Restated
                  Shareholders Agreement, dated as of November 16, 1999 (as
                  amended heretofore, the "Shareholders Agreement").

         B.       The Company, certain Investors and Founders have entered into
                  that certain Series C Preferred Stock Purchase Agreement,
                  dated of even date herewith (the "Purchase Agreement"),
                  pursuant to which the Company will issue and sell, and the
                  Investors and Founders will purchase, certain shares of the
                  Company's Series C Preferred Stock (the "Stock").

         C.       As a condition to the closing of the purchase of the Stock
                  under the Purchase Agreement, the Company, Investors, Founders
                  and Holders desire to amend the Shareholders Agreement as
                  provided herein.

         D.       The Investors and Founders acknowledge that the Company has
                  complied with its obligations under Section 3 of the
                  Shareholders Agreement relating to Rights of First Refusal in
                  connection with the issuance of the Stock under the Purchase
                  Agreement and waive such right solely in connection with the
                  issuance of Stock under the Purchase Agreement.

         Now, Therefore, in consideration of the foregoing, the mutual covenants
and agreements herein contained and other good and valuable consideration, the
receipt and adequacy of which is hereby acknowledged, the parties hereby agree
that the Shareholders Agreement shall be amended as follows:

                                   AMENDMENTS

1. In Section 1 of the Shareholders Agreement, the definition of "Preferred
Stock" shall be amended in its entirety to read as follows:

                  "Preferred Stock" shall mean any series of preferred stock of
         the Company, including, without limitation, the Series A Preferred
         Stock, the Series B Preferred Stock and Series C Preferred Stock.

2. In Section 1 of the Shareholders Agreement, the following definition shall be
added:

<PAGE>   57

                  "Series C Preferred Stock" shall mean the Series C Preferred
         Stock, $0.001 par value per share, of the Company, or any other
         capital stock of the Company into which such stock is reclassified or
         reconstituted or any securities convertible into, or exchangeable or
         exercisable for, any of the foregoing, in each case, at any time
         outstanding.

3. Section 2.2(a) of the Shareholders Agreement shall be amended in its entirety
to read as follows:

         2.2 Right of First Offer.

                  (a) If at any time, other than pursuant to an Exempt Transfer,
         any Shareholder or their Related Party (each, a "Seller") desires to
         Transfer any or all of the Shares or any rights to Shares held by such
         Seller to any person, such Seller shall reduce to writing the terms
         pursuant to which Seller desires to Transfer such Shares (a "Transfer
         Offer"). The Transfer Offer shall identify the number of Shares to be
         transferred, the consideration for the Shares, the identity of any
         third party offeror, and all the other terms and conditions of such
         Transfer Offer. The Seller shall deliver the Transfer Offer to the
         Company, Founders and Investors. Notwithstanding anything to the
         contrary contained herein, for any Transfer by an Investor or Founder,
         or their Exempt Transferees, of:

                           (i) Series A Preferred Stock, the rights set forth in
                  this Section 2.2 shall be limited to Transfer Offerees holding
                  Series A Preferred Stock;

                           (ii) Series B Preferred Stock, the rights set forth
                  in this Section 2.2 shall be limited to Transfer Offerees
                  holding Series B Preferred Stock; or

                           (iii) Series C Preferred Stock, the rights set forth
                  in this Section 2.2 shall be limited to Transfer Offerees
                  holding Series C Preferred Stock.

         Notwithstanding anything to the contrary contained herein, Section 2.3
         shall not apply to any such Transfer of Series B Preferred Stock or
         Series C Preferred Stock.

                                  MISCELLANEOUS

1. Interpretation. Except as expressly amended by this Amendment, the
Shareholders Agreement shall remain in full force and effect without change.

2. Counterparts. This Amendment may be executed in any number of counterparts,
each of which when executed and delivered shall be an original, but all of which
together shall constitute one and the same instrument.

3. Effective Time. This Amendment shall be effective following its execution by
the Founders who hold two thirds of the Shares (as defined in the Shareholders
Agreement) held by

<PAGE>   58

the Founders, the Investors who hold two-thirds of the Shares (as defined in the
Shareholders Agreement) held by the Investors and Holders who hold 51% of the
Shares (as defined in the Shareholders Agreement) held by Holders, each voting
as a class, in accordance with Section 7.1 of the Shareholders Agreement.

4. Additional Investors. Each party who purchases Stock pursuant to the Purchase
Agreement agrees to be bound by the terms of the Shareholders Agreement and
shall be deemed an additional "Investor" for all purposes thereunder.

                            [signature pages follow]

<PAGE>   59

                                   EXHIBIT F

                                 CAPITALIZATION

                     OF THE COMPANY AS OF THE CLOSING DATE

<PAGE>   60

     Array BioPharma          CAPITALIZATION TABLE                     8/31/2000
     Confidential

Ownership Structure as of
August 31, 2000

<TABLE>
<CAPTION>
                                                   SHARES        PURCHASE                        PURCHASE
                                                  COMMON @        PRICE          SHARES A @        PRICE           SERIES B @
STOCKHOLDERS                         OPTIONS      $0.235/SH.      COMMON         $1.00/SH.       SERIES A           $2.50/SH.
------------                         -------      ----------    -----------      ----------     -----------        ----------
<S>                                  <C>          <C>           <C>              <C>            <C>                <C>
ARCH Venture Fund III, LP                                       $        --       1,500,000     $ 1,500,000         604,446
FRAZIER & Company                                               $        --       1,500,000     $ 1,500,000         604,446
BOULDER VENTURES II                                 130,500     $    30,668         870,000     $   870,000         403,166
BOULDER VENTURES II ANNEX                            19,500     $     4,583         130,000     $   130,000          60,243
FALCON TECHNOLOGY                                   150,000          35,250       1,000,000     $ 1,000,000         463,409
ADVENT International, Inc.                                      $        --         750,000     $   750,000         120,000
MITSUI & Company                                                $        --         250,000     $   250,000         100,741
Marvin Caruthers                                     18,750     $     4,406         250,000     $   250,000          80,000
Frank Bonsal                                                                         50,000     $    50,000          10,000
Mike Carruthers                       100,387        44,505     $    10,459          25,000     $    25,000           8,000
Richard Daly                                                                         25,000     $    25,000           9,600
Christopher Ozeroff                                                                  20,000     $    20,000           4,000
William Roberts                                                                      10,000     $    10,000           2,400
Theresa A. Koch                        20,819        10,457     $     2,457           5,000     $     5,000          12,500

FOUNDING MANAGEMENT
Kevin Koch                             76,172       664,396     $   156,074                                          26,000
Tony Piscopio                          65,734       662,977     $   155,741                                          30,000
KC Nicolaou                                         648,654     $   152,375                                         252,000
David Snitman                          76,172       664,397     $   156,075         250,000     $   250,000         356,148

SERIES C INVESTORS
Kirby Cramer
Joseph Lefkoff
Vector Fund Management
Mosaix Ventures
                                    ---------     ---------     -----------     -----------     -----------       ---------
Total Series A, B & Founders          339,284     3,014,136     $   708,087       6,635,000     $ 6,635,000       3,147,099

Other - Preferred Series B                                                                                           52,900
Other - Common                                      851,607     $   287,728

SILICON VALLEY (Warrants)                                                            47,000                          50,000
LTI (Warrants)                                                                       16,500

Options Issued less included in
Founders and Investors (above)      2,658,855
                                    ---------     ---------     -----------     -----------     -----------       ---------
Total                               2,998,139     3,865,743     $   995,814       6,698,500     $ 6,635,000       3,249,999
                                    =========     =========     ===========     ===========     ===========       =========

<CAPTION>

                                    PURCHASE                         PURCHASE         TOTAL          POST
                                     PRICE         SERIES C @         PRICE           SHARES        TOTAL %
STOCKHOLDERS                        SERIES B        $6.00/SH.        SERIES C         (POST)       OWNERSHIP
------------                       -----------     -----------     -----------      ----------     ---------
<S>                                <C>             <C>             <C>              <C>            <C>
ARCH Venture Fund III, LP          $ 1,511,116         204,779     $ 1,228,674       2,309,225       12.50%
FRAZIER & Company                  $ 1,511,116          16,667     $   100,002       2,121,113       11.48%
BOULDER VENTURES II                $ 1,007,914         136,587     $   819,522       1,540,253        8.34%
BOULDER VENTURES II ANNEX          $   150,608          20,410     $   122,460         230,153        1.25%
FALCON TECHNOLOGY                  $ 1,158,522         156,997     $   941,982       1,770,406        9.58%
ADVENT International, Inc.         $   300,000          50,000     $   300,000         920,000        4.98%
MITSUI & Company                   $   251,853          34,130     $   204,780         384,871        2.08%
Marvin Caruthers                   $   200,000          33,936     $   203,616         382,686        2.07%
Frank Bonsal                       $    25,000           5,834     $    35,004          65,834        0.36%
Mike Carruthers                    $    20,000           3,332     $    19,992         181,224        0.98%
Richard Daly                       $    24,000                                          34,600        0.19%
Christopher Ozeroff                $    10,000          13,621     $    81,726          37,621        0.20%
William Roberts                    $     6,000           1,207     $     7,242          13,607        0.07%
Theresa A. Koch                    $    31,250                                          48,776        0.26%

FOUNDING MANAGEMENT
Kevin Koch                         $    65,000                                         766,568        4.15%
Tony Piscopio                      $    75,000           1,667     $    10,002         760,378        4.11%
KC Nicolaou                        $   630,000          50,000     $   300,000         950,654        5.14%
David Snitman                      $   890,371         266,667     $ 1,600,002       1,613,384        8.73%

SERIES C INVESTORS
Kirby Cramer                                            83,333     $   499,998          83,333
Joseph Lefkoff                                           4,166     $    24,996           4,166
Vector Fund Management                                 416,667     $ 2,500,002         416,667
Mosaix Ventures                                        166,667     $ 1,000,002         166,667
                                   -----------       ---------     -----------      ----------      ------
Total Series A, B & Founders       $ 7,867,750       1,666,667     $10,000,002      14,802,186       80.10%

Other - Preferred Series B         $   132,250                                          52,900        0.29%
Other - Common                                                                         851,607        4.61%

SILICON VALLEY (Warrants)                                                               97,000        0.52%
LTL (Warrants)                                                                          16,500        0.09%

Options Issued less included in
Founders and Investors (above)                                                       2,658,855       14.39%
                                   -----------     -----------     -----------      ----------      ------
Total                              $ 8,000,000     $ 1,666,667     $10,000,002      18,479,048      100.00%
                                   ===========     ===========     ===========      ==========      ======
</TABLE>

<PAGE>   61

                                   EXHIBIT G

                       OPINION OF COUNSEL TO THE COMPANY

<PAGE>   62

                                 August 31, 2000

To:  The Purchasers under the Series C Preferred Stock Purchase Agreement dated
     August 31, 2000

         Re:  Array BioPharma Inc.; Series C Preferred Stock Purchase Agreement

Ladies and Gentlemen:

         This firm has acted as special counsel to Array BioPharma Inc., a
Delaware corporation (the "Company"), in connection with the Series C Preferred
Stock Purchase Agreement, dated of even date herewith (the "Purchase
Agreement"), among the Company and certain investors identified as "Purchasers"
on the signature pages thereto (collectively, the "Purchasers"). This opinion
letter is furnished to you pursuant to the requirements set forth in Section
5.1(j) of the Purchase Agreement. Capitalized terms used herein that are defined
in the Purchase Agreement shall have the meanings set forth in the Purchase
Agreement, unless otherwise defined herein.

         For purposes of this opinion letter, we have examined copies of the
following documents:

                  1. The Purchase Agreement, Amendment No. 2 to Amended and
Restated Shareholders Agreement and Amendment No. 1 to Amended and Restated
Investor Rights Agreement (collectively, the "Documents").

                  2. The Company's Amended and Restated Certificate of
Incorporation (the "Certificate"), as certified by the Secretary of State of the
State of Delaware on August 31, 2000 and as certified by the Secretary of the
Company on the date hereof as being complete, accurate and in effect.

                  3. The Bylaws of the Company, as certified by the Secretary of
the Company on the date hereof as being complete, accurate and in effect.

                  4. A certificate of good standing of the Company issued by the
Secretary of State of the State of Delaware dated August 31, 2000.

                  5. Foreign qualification certificate issued by the Secretary
of State of the State of Colorado dated August 21, 2000.

                  6. Resolutions of the Board of Directors of the Company
adopted by unanimous written consent dated August 22, 2000, as certified by the
Secretary of the Company on the date hereof as being complete, accurate and in
effect, relating to, among other things, authorization of the Purchase Agreement
and the consummation of the transactions contemplated thereunder.

<PAGE>   63

The Purchasers
August 31, 2000
Page 2

                  7. A certificate of an officer of the Company dated the date
hereof as to certain facts relating to the Purchase Agreement and the Company.

                  8. A certificate of the Secretary of the Company, dated the
date hereof, as to the incumbency and signatures of certain officers of the
Company.

                  9. The common and preferred stock ledger of the Company
certified by the Secretary of the Company as being accurate and complete as of
the date hereof.

         We have not, except as specifically identified above, made any
independent review or investigation of factual matters, including the assets,
business or affairs of the Company. In our examination of the Documents and the
aforesaid certificates, records, documents and agreements, we have assumed the
genuineness of all signatures (other than those on behalf of the Company in the
Documents), the legal capacity of all natural persons, the accuracy and
completeness of all documents submitted to us, the authenticity of all original
documents and the conformity to authentic original documents of all documents
submitted to us as copies (including telecopies). We also have assumed the
accuracy, completeness and authenticity of the foregoing certifications (of
public officials, governmental agencies and departments and corporate officers)
and statements of fact, on which we are relying, and have made no independent
investigations thereof. In rendering the following opinions with respect to the
Company, we have relied as to factual matters, without independent
investigation, upon the representations, warranties and certifications made by
the Company in or pursuant to the Documents and upon the officer's certificate
identified in Paragraph 7 above and the Secretary's certificate identified in
Paragraph 8 above. This opinion letter is given, and all statements herein are
made, in the context of the foregoing.

         As used in this opinion letter, the phrase "to our knowledge" means
the actual knowledge (that is, the conscious awareness of facts or other
information) of lawyers in the firm who have given substantive legal attention
to representation of the Company since the Company has been a client of the
firm.

         For purposes of this opinion letter, we have assumed that (i) the
Purchasers have all requisite power and authority under all applicable laws,
regulations and governing documents to execute, deliver and perform their
respective obligations under the Documents, (ii) the Purchasers have duly
authorized, executed and delivered the Documents, (iii) the Purchasers, to the
extent they are not individuals, are validly existing and in good standing in
all necessary jurisdictions, (iv) the Documents constitute valid and binding
obligations, enforceable against the Purchasers in accordance with their
respective terms and (v) there has been no material mutual mistake of fact or
misunderstanding or fraud, duress or undue influence, in connection with the
negotiation, execution or delivery of the Documents.

<PAGE>   64

The Purchasers
August 31, 2000
Page 3

         This opinion letter is based as to matters of law solely on applicable
provisions of (i) the Delaware General Corporation Law and (ii) Colorado
contract law (but not including any statutes, ordinances, administrative
decisions, rules or regulations of any political subdivision of the State of
Colorado), except as to Paragraph (i) below, which is limited to the Securities
Act of 1933, as amended, and we express no opinion as to any other laws,
statutes, ordinances, rules or regulations (such as state securities laws or
regulations, antitrust or unfair competition laws or regulations, tax laws or
regulations or communications laws or regulations).

         Based upon, subject to and limited by the foregoing, we are of the
opinion that:

         (a) The Company was incorporated and is validly existing and in good
standing as of the date specified in the certificate referred to in Paragraph 4
above under the laws of the State of Delaware.

         (b) The Company is authorized to transact business as a foreign
corporation in the State of Colorado as of the date of the certificate specified
in Paragraph 5 above. The Company is not qualified as a foreign corporation in
any jurisdiction other than the State of Colorado.

         (c) The Company has the requisite corporate power and corporate
authority to own or lease its properties and assets and to conduct its business
as it is currently being conducted.

         (d) The Company has the corporate power and corporate authority to
enter into the Documents and to perform its obligations thereunder.

         (e) The Documents are valid, binding and enforceable against the
Company in accordance with their terms, except as may be limited by bankruptcy,
insolvency, reorganization, moratorium or other laws affecting creditors' rights
(including, without limitation, the effect of statutory and other law regarding
fraudulent conveyances, fraudulent transfers and preferential transfers) and as
may be limited by the exercise of judicial discretion and the application of
principles of equity including, without limitation, requirements of good faith,
fair dealing, conscionability and materiality (regardless of whether such
agreements are considered in a proceeding in equity or at law). In addition, we
express no opinion as to the indemnification and contribution provisions
contained in Section 2 of the Amended and Restated Investor Rights Agreement.

         (f) The execution, delivery and performance as of the date hereof by
the Company of the Documents have been duly authorized by all necessary
corporate action of the Company.

         (g) The authorized, issued and outstanding capital stock of the Company
as of August 31, 2000 are as set forth in Section 3.2 of the Purchase Agreement.
The shares of common stock issuable upon conversion of the Series C Preferred
Stock (the "Conversion Shares") have been duly and validly reserved for
issuance. When issued in compliance with the Certificate and the

<PAGE>   65

The Purchasers
August 31, 2000
Page 4

Purchase Agreement, the Conversion Shares will be validly issued, fully paid and
nonassessable, and will be free of any liens or encumbrances created by the
Company; provided, however, that the Conversion Shares are subject to
restrictions on transfer under state and/or federal securities laws and the
Documents. The shares of Series C Preferred Stock, when issued in accordance
with the Certificate and the Purchase Agreement, will be validly issued, fully
paid and non-assessable, and will be free of liens or encumbrances created by
the Company; provided, however, that the shares of Series C Preferred Stock are
subject to restrictions on transfer under state and/or federal securities laws
and the Documents. Except as provided in the Documents, to our knowledge, there
are no outstanding rights, options, warrants, conversion privileges, preemptive
rights, or other agreements or commitments obligating the Company to issue or
transfer any additional shares of Series C Preferred Stock.

         (h) The execution, delivery, and performance as of the date hereof by
the Company of the Documents do not violate the Certificate or Bylaws of the
Company.

         (i) Based on the covenants and representations of the Purchasers set
forth in the Purchase Agreement and the representations of the Company officer
referred to in Paragraph 7 above, the offer, issuance and sale of the Series C
Preferred Stock to the Purchasers pursuant to the Purchase Agreement is exempt
from the registration requirements of the Securities Act of 1933, as amended.

         The opinion expressed in Paragraph (e) above shall be understood to
mean only that if there is a default in performance of an obligation, (i) if a
failure to pay or other damage can be shown and (ii) if the defaulting party can
be brought into a court which will hear the case and apply the governing law,
then, subject to the availability of defenses, and to the exceptions set forth
in Paragraph (e) above, the court will provide a money damage (or perhaps
injunctive or specific performance) remedy.

         We assume no obligation to advise you of any changes in the foregoing
subsequent to the delivery of this opinion letter. This opinion letter has been
prepared solely for your use in connection with transactions contemplated by the
Purchase Agreement on the date hereof, and should not be quoted in whole or in
part or otherwise be referred to, nor be filed with or furnished to any
governmental agency or other person or entity, without the prior written consent
of this firm.

                                                  Very truly yours,

                                                  HOGAN & HARTSON L.L.P.<PAGE>   1
                                                                    EXHIBIT 10.8

                                   AMGEN INC.
                                1885 33RD STREET
                                BOULDER, COLORADO

                                      LEASE

         THIS LEASE (this "Lease") is made as of the ___ day of July, 1998, by
and between AMGEN INC., a Delaware corporation, as landlord ("Landlord"), whose
address is One Amgen Center Drive, Thousand Oaks, California 91320, and the
Tenant named in Section 1 below.

1.       BASIC PROVISIONS.

         a.   TENANT NAME

         b.   AND CONTACT PEOPLE:           Array BioPharma Inc.
                                            1885 33rd Street Building AC-1
                                            Boulder, Colorado 80301-2505
                                            Attn:  David Snitman

         c.   PREMISES:                     Amgen Building AC-1
                                            1885 33rd Street
                                            Boulder, CO 80301-2505

         d.   RENT:                         $41,173/mth., triple net

         e.   SECURITY DEPOSIT:             12 months rent (with
                                            decrease after one year
                                            pursuant to Section 6.a)

         f.   INITIAL TERM:                 Three years

         g.   COMMENCEMENT DATE:            July 15, 1998

         h.   LEASE EXTENSION OPTION:       One two-year option with rental
                                            increase

         i.   TENANT'S SHARE OF INSURANCE, PARKING LOT MAINTENANCE, FIRE AND
              SPRINKLER PROTECTION SYSTEM MONITORING AND MAINTENANCE,
              LANDSCAPING CARE AND IRRIGATION:  15%

         j.   PERMITTED USE:                Industrial laboratory and accessory
                                            office use.

         k.   ADDITIONAL INFORMATION:
                                      ------------------------------------------

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

<PAGE>   2

2.       LEASE GRANT.

         Landlord hereby leases to Tenant and Tenant hereby leases from Landlord
the Premises as described on EXHIBIT A attached hereto, which is located at 1885
33rd Street, Boulder, Colorado, in Amgen Building AC-1 of the "Amgen Complex,"
which consists of Amgen Buildings AC-1, AC-2, AC-3 and AC-4.

3.       USE.

         a. Permitted Use. The premises may be used and occupied only for
industrial laboratory and accessory office use and for no other purpose
whatsoever.

         b. Uses Prohibited. Tenant shall not do anything which will increase
the existing rate of any insurance upon the Amgen Complex, or cause a
cancellation of such insurance. Tenant shall not do anything which will
interfere with other tenants at the Amgen Complex. Tenant shall not use the
Premises for any improper, immoral, unlawful or objectional purpose. Tenant
shall not permit any nuisance about the Premises or the Amgen Complex. Tenant
shall not commit any waste upon the Premises or the Amgen Complex.

         c. Compliance with Law. Tenant shall have sole responsibility to ensure
that its use complies with all local land use regulations and zoning laws.
Moreover, Tenant shall comply with all laws, statutes, ordinances and
governmental rules, regulations or requirements now in force or which may
hereafter be in force (including without limitation, environmental laws) and
with the requirements of any board of fire underwriters or other similar bodies
now or hereafter constituted relating to the Premises.

4.       ACCEPTANCE OF PREMISES.

         a. Commencement Date. The "Commencement Date" of this Lease shall be
July 15, 1998, or sooner, at Landlord's option.

         b. Acceptance of Premises. Prior to the Commencement Date, Landlord
shall notify Tenant that the Premises are available for inspection. At such
time, Tenant shall have the right to walk-through inspections of the Premises.
When Tenant occupies the Premises, Tenant shall be deemed to have fully accepted
the Premises in "as is" condition. Landlord and Landlord's agents hereby
disclaim any express or implied representations, warranties or promises with
respect to the physical condition of the Amgen Complex, the land upon which it
is erected, the Premises, the suitability of the Premises for Tenant's intended
purpose or use, or any other matter or thing affecting or related to the
Premises except as herein expressly set forth.

                                      -2-
<PAGE>   3

5.       TERM; HOLDOVER.

         a. Term. The initial term of this Lease (the "Initial Term") shall
commence on the Commencement Date and terminate at midnight on July 14, 2001,
unless sooner terminated hereunder. Tenant may extend the Initial Term an
additional two years under the terms set forth in Section 5.b. "Term" as used
herein shall refer to the Initial Term and any extension thereof.

         b. Lease Extension Option. Tenant shall have the right, exercisable by
delivery of written notice to Landlord not later than nine months prior to the
end of the Initial Term (the "Expiration Date"), to extend the Term of this
Lease for a further period of two years commencing on the first day after the
Expiration Date and expiring two years thereafter ("Extension"). All terms and
conditions of this Lease shall apply to the Extension which shall include all
space then occupied under this Lease, except that the Rent shall be increased as
set forth in EXHIBIT B, attached hereto and incorporated herein by reference,
and there shall be no more extension options.

         c. Holdover. After the expiration of the Term, this Lease shall
continue from month to month, if Tenant retains possession of the Premises, at
the rent of 150% of the Rent due during the last month before expiration and
otherwise on the same terms and conditions as herein provided, unless and until
either Landlord or Tenant terminates this Lease by giving the other written
notice at any time.

6.       RIGHT OF FIRST OPTION.

         Landlord hereby grants to Tenant a right of first option (the "Option")
to lease any additional space adjacent to the Premises which becomes available
for lease from time to time during the Term of this Lease. Landlord shall give
notice ("Option Notice") to Tenant of the terms and conditions ("Landlord's
Offer"), including the rental rate, upon which such space is available for
lease. Tenant shall have ten days ("Option Exercise Period") after receipt of
the Option Notice to accept or reject Landlord's Offer in writing. If Tenant has
not accepted or rejected Landlord's Offer by the expiration of the Option
Exercise Period, Landlord's Offer shall be deemed to be rejected by Tenant.

7.       SECURITY DEPOSIT.

         a. Terms of Deposit. Simultaneously with the execution of this Lease,
Tenant shall pay to Landlord the sum of $494,076 to be held by Landlord as a
security deposit to secure Tenant's faithful performance of all terms,
conditions and covenants of this Lease, including without limitation the payment
of all Rent and Additional Rent due hereunder. Such security deposit shall be in
the form of a letter of credit or six-month certificate of deposit with a bank
designated by Tenant satisfactory to Landlord. Such certificate of deposit shall
be placed in the name of Landlord and shall automatically renew for additional
six-month periods. Any and all interest earned thereon shall belong to Tenant.
After the first year of this Lease and on condition that no defaults have
occurred hereunder, the principal amount may be reduced to six months'

                                      -3-
<PAGE>   4

rent or $247,038. Upon full performance of this Lease and subject to the
provisions of Section 7.b, the security deposit and any uncollected interest
earned thereon shall be refunded to Tenant.

         b. Use of Deposit. If at any time during the Term, Tenant shall be in
default in the performance of any provision of this Lease, Landlord may (but
shall not be required to) use the security deposit, or as much thereof as is
reasonably necessary, in payment of any Rent, Additional Rent or other sums due
under this Lease in default, in reimbursement of any expense incurred by
Landlord on Tenant's behalf, including but not limited to repairs to or
replacements on the Premises, or in payment of any damages incurred by Landlord
by reason of default. In such event, Tenant shall, on written demand of
Landlord, forthwith remit to Landlord a sufficient amount in cash to restore
such deposit to its original amount. If the claims of Landlord exceed the
deposit provided for herein, Tenant shall remain liable for the balance of such
claims.

8.       RENT.

         Tenant shall pay to Landlord, without offset, deduction, notice or
demand, rent ("Rent") for the Premises as follows:

         a. Rent. Tenant shall pay the monthly sum specified in the Rent
Schedule shown on EXHIBIT B ("Rent"), in advance on or before the first day of
each and every calendar month commencing as of August 1, 1998, during the Term
hereof, except the first month's Rent shall be prorated and due and payable on
or before July 15, 1998. Rent shall be paid to Landlord in lawful money of the
United States of America at the following address:

                           Amgen Inc.
                           Attn: Candace Halloran, Accounting Operations
                           One Amgen Center Drive
                           Thousand Oaks, California 91320

         or such place as Landlord may from time to time designate in writing.

         b. Additional Rent. Any costs that Tenant is required to pay, if paid
by Landlord, shall become "Additional Rent" due under this Lease. Additional
Rent shall be due to Landlord with the next installment of Rent due, or if no
such installment is due, within 15 days following receipt by Tenant of a written
invoice of such costs. Additional Rent may include, but is not limited to, all
real property taxes for the Premises; assessments on the Premises; modifications
requested by Tenant to any system used in the Amgen Complex that affect the
Premises; costs of capital improvements, major structural repairs, boiler
replacement and other capital replacements, and major roof repairs, provided
that any Additional Rent for such items shall be amortized over the projected
life of the improvement or repair; and Tenant's share of insurance, parking lot
maintenance, fire and sprinkler protection system monitoring and maintenance,
and landscaping care and irrigation. For example, if a boiler serving the
Premises is replaced at the beginning of the second year of the Term, at a
replacement cost of $200,000.00, and the boiler has a useful life of 20 years,
Tenant's amortized share of the boiler replacement would be at a rate

                                      -4-
<PAGE>   5

of $10,000.00 per year during the remaining Term. Landlord has disclosed to
Tenant that real property taxes and assessments for the Premises for calendar
year 1997 were $32,270, and the estimated real property taxes and assessments
for calendar year 1998 are $32,270. For all purposes of this Lease, the term
"Rent" shall be deemed to include Additional Rent.

         c. Personal Property Taxes. Tenant shall pay before delinquency any
taxes upon Tenant's leasehold improvements, equipment, furniture, fixtures
(including without limitation the Fixtures), and any other personal property
located in the Premises. In the event any such personal property shall be
assessed and taxed with the real property, Tenant shall pay to Landlord its
share of such taxes within ten days after timely delivery to Tenant of a
statement in writing setting forth the amount of such taxes applicable to
Tenant's personal property.

         d. Late Charge. Tenant hereby acknowledges that late payment by Tenant
to Landlord of Rent or other sums due hereunder will cause Landlord to incur
costs which will be difficult to ascertain. Such costs include, but are not
limited to, processing and accounting charges, attorneys' fees, and late charges
which may be imposed upon Landlord by terms of any mortgage or trust deed
encumbering the Amgen Complex. Accordingly, if any installment of Rent or any
sum due from Tenant shall not be received by Landlord within five business days
after said amount is due, Tenant shall pay to Landlord on demand a late charge
of five percent of such overdue amount. Any Rent or sums due from Tenant which
are more than one month delinquent shall bear interest at the rate of 18 percent
per annum from the due date. Tenant shall pay any attorneys' fees incurred by
Landlord by reason of Tenant's failure to pay such amounts. Tenant shall pay on
demand $25 for any check returned for insufficient funds. All such charges shall
also be deemed to be Rent hereunder.

9.       MAINTENANCE, UTILITIES AND SECURITY.

         a. Landlord's Maintenance Obligations. Landlord shall maintain the
parking lot, landscaping and structural portions of the Premises, including the
exterior walls and roof, unless such repairs are caused by the act or omission
of any duty of Tenant, its agents, servants, employees, invitees, subtenants,
licensees, assignees or trespassers, in which case Tenant shall pay to Landlord
the actual cost of such maintenance and repairs. Landlord shall be responsible
for replacement of boilers and mechanical, electrical, elevator and HVAC
systems, subject to the provisions of Section 8(b) of this Lease. Landlord shall
also be responsible for monitoring and maintenance of the fire monitoring system
and sprinkler protection system, provided that Tenant shall pay as Additional
Rent 15 percent of all costs associated with such monitoring and maintenance.
There shall be no abatement of Rent and no liability of Landlord by reason of
any reasonable injury to or reasonable interference with Tenant's business
arising from the making of any necessary repairs, alterations or improvements.
Tenant waives the right to make repairs at Landlord's expense under any law,
statute or ordinance now or hereafter in effect. Landlord agrees to promptly and
diligently perform any such maintenance and repair for which it is responsible.

                                      -5-
<PAGE>   6

         b. Tenant's Obligations. Tenant shall establish contracts with
reputable contractor(s) for scheduled preventative maintenance and repair on
building-specific boilers and mechanical, electrical, elevator and HVAC systems.
It shall be Tenant's obligation to keep in good order, condition and repair all
portions of the Premises that are not the obligation of Landlord. In addition,
Tenant is responsible for monitoring and maintenance of the fire extinguishers
on the Premises, including but not limited to conducting periodic fire safety
inspections to ensure that the Premises complies with all local laws, codes and
regulations. Tenant shall contract and pay for all water, gas, sewer charges,
electricity, telephone service, pest control, trash removal and all other
services and utilities supplied to the Premises, together with any taxes
thereon. All telecommunications services (voice and data) desired by Tenant
shall be obtained at Tenant's sole cost and risk from providers authorized by
Landlord and the appropriate governmental authorities to provide such services
to the Amgen Complex. Landlord agrees to provide consultative assistance to
Tenant, where necessary, in the installation of such telecommunications
services, but in no event shall Landlord have any liability or obligation to
Tenant in connection with the failure of such telecommunications services or any
interruption therein or interference therewith (even if caused by the negligent
acts or omissions of Landlord, its agents, contractors, and employees) and
Tenant waives and releases all claims therefor, whether now existing or
hereafter arising. Furthermore, Landlord shall have no obligation of any kind or
character with respect to the maintenance or operation of any such
telecommunications system, irrespective of the points of demarcation therein and
will coordinate access for the appropriate telecommunications carrier to the
point of demarcation which is located outside of the Premises with a minimum of
one hour's notice during normal business hours and a minimum of four hours'
notice outside of normal business hours. In no event shall Tenant use or install
in the Premises any wireless communications equipment (other than the use of
cellular telephones) without the prior written consent of Landlord. Tenant shall
not alter, modify, remove or add any voice and/or data cable to the Premises or
the Amgen Complex without prior written consent of Landlord. Tenant shall
provide Landlord with its plan for such facilities and will secure its own
telecommunication demarcation point within a reasonable time. No entrance
facilities services installed, purchased or owned by Tenant shall pass through
or terminate within the Amgen Complex except within the Premises.

         c. Building Management System. Landlord shall have no obligation to
supply utility service to the Premises. Notwithstanding the foregoing,
Landlord's building management system for the Amgen Complex (the "BMS") is
currently programmed to regulate and control certain utilities supplied to the
Premises. Therefore, Landlord agrees, as an accommodation to Tenant, to continue
to operate the BMS for the Premises so long as Landlord occupies any portion of
the Amgen Complex and Tenant's needs can be reasonably accommodated through the
BMS, provided that Landlord will give three months' notice to Tenant prior to
discontinuing operation of the BMS and Tenant may elect to continue to operate
the BMS for the Premises (at Tenant's sole cost and expense, including the cost
of modifications required to make the BMS control only the Premises) or to
install a new system at Tenant's cost. Tenant agrees to designate an employee
who will be Landlord's contact for BMS matters. In the event Tenant desires to
make substantial modifications to the BMS, or to make other arrangements for its
utility

                                      -6-
<PAGE>   7

management, Tenant shall first obtain the written approval of Landlord, and
shall make such changes at Tenant's sole cost and expense.

                  Because the BMS services are being provided solely as an
accommodation to Tenant, and not as an obligation of Landlord, Landlord shall
not be deemed to be in default under this Lease for any reason whatsoever
relating to the BMS, including without limitation, breach of quiet enjoyment,
damage to property or injury to persons. Moreover, Tenant hereby waives and
releases all claims against Landlord for any loss, liability or injury that
arises out of or is incurred in connection with the BMS or Landlord's operation
thereof.

         d. Security. Landlord will provide Tenant with key locks for all entry
doors. Notwithstanding the foregoing, Tenant will be responsible for providing
security on the Premises and adjacent areas, including but not limited to the
sidewalks and parking areas.

10.      TENANT REPAIRS AND ALTERATIONS.

         a. Repairs; Surrender. Tenant shall, at Tenant's sole cost and expense,
keep the Premises and every part thereof in good condition and repair. Subject
to the provisions of EXHIBIT C, Tenant shall, upon the expiration or sooner
termination of this Lease, surrender the Premises, together with all Fixtures
appurtenant thereto as described in EXHIBIT A, to Landlord in good and operating
condition, broom clean, ordinary wear and tear excepted. Tenant shall not be
obligated to make structural repairs or repairs necessitated by fire or other
casualty. Notwithstanding the foregoing, all damage to the Premises, the
Fixtures or to any other part of the Amgen Complex caused by carelessness,
omission, neglect or improper conduct of Tenant, its employees, agents,
subtenants, assignees, invitees or trespassers shall be repaired promptly by
Tenant at its sole cost and expense, to the reasonable satisfaction of Landlord.

         b. Signage. Tenant shall seek the prior written consent of Landlord,
such consent not to be unreasonably withheld, before installing any decals or
signage on or about the Premises. All decals and signage approved under this
Section 10 shall be removed from the Premises at the termination of the Lease.

         c. Alterations and Modifications. Tenant shall not make any
alterations, additions or improvements to the Premises without the prior written
consent of Landlord. Plans and specifications for any desired building or
facility modifications must be submitted to and approved by Landlord prior to
implementation by Tenant. The cost of any modifications requested by Tenant to
systems used in the Amgen Complex that affect the Premises, including but not
limited to the fire monitoring system, sprinkler protection system and BMS, if
any, shall be charged to Tenant as Additional Rent. No Fixtures shall be removed
from the Premises or modified in any respect without the prior written consent
of Landlord. Consent or approval of Landlord, where required for actions by
Tenant in this paragraph, shall not be unreasonably withheld. Tenant shall keep
posted on the Premises, and shall personally serve upon contractors and
subcontractors, a notice stating that Landlord's interest in the Amgen Complex
shall not be subject to any lien for Tenant's work. Tenant shall provide
Landlord with certificates evidencing

                                      -7-
<PAGE>   8

that all contractors and subcontractors have adequate workman's compensation
insurance and builder's risk insurance satisfactory to Landlord. Any such work
including wall covering, paneling and built-in cabinet work, but excepting
movable furniture and trade fixtures, shall at once become a part of the realty
and belong to Landlord and shall be surrendered with the Premises. Upon the
expiration of the Term hereof (the "Expiration Date"), Tenant shall, if
requested by Landlord, within five days after the Expiration Date, at Tenant's
sole cost and expense, remove any alterations, additions, or improvements made
by Tenant, and Tenant shall, at its sole cost and expense, repair any damage to
the Premises caused by such removal. If Tenant fails to remove any such
alterations, additions or improvements, Landlord may remove same at Tenant's
sole cost and expense. Tenant shall also remove all furnishings, equipment,
trade fixtures and other removable equipment, except those Fixtures described on
EXHIBIT A, within five days after the Expiration Date. If Tenant fails to remove
such property, then Tenant hereby grants to Landlord the option, exercisable at
any time thereafter without the requirements of any notice to Tenant, (i) to
treat such property, or any portion thereof, as being abandoned by Tenant to
Landlord, whereupon Landlord shall be deemed to have full rights of ownership
thereof; (ii) to elect to remove and store such property, or any portion
thereof, on Tenant's behalf (but without assuming any liability to any person)
and at Tenant's sole cost and expense, with reimbursement therefor to be made to
Landlord upon demand; and/or (iii) to sell, give away, donate or dispose of as
trash or refuse any or all of such property without any responsibility to
deliver to Tenant any proceeds therefrom.

         d. Mechanics' and Materialmen's Liens. Tenant shall have no authority
or power, express or implied, to create or cause any mechanic's or materialmen's
lien, charge or encumbrance of any kind against the Premises or the Amgen
Complex or any portion thereof. Tenant shall promptly cause any such liens which
have arisen by reason of any work or materials claimed to have been provided to
or undertaken by or through Tenant to be released by payment, bonding or
otherwise within thirty days after request by Landlord, and Tenant shall
indemnify Landlord against losses arising out of any such claim. In addition,
Tenant shall give such notices and shall cause the Premises to be posted in
accordance with Colorado Revised Statutes 38-22-105, as such may be amended
from time to time, prior to the commencement of any work on the Premises,
whether or not Landlord has consented to such work. Tenant's indemnification of
Landlord contained in this Section 10(c) shall survive the expiration or earlier
termination of this Lease.

11.      INDEMNITY.

         Tenant shall indemnify, defend (with counsel satisfactory to Landlord)
and hold harmless Landlord and its partners, affiliates, officers, directors,
shareholders, lenders, employees, agents, successors and assigns ("Indemnities")
from and against any and all liabilities, claims, fines, penalties, costs,
damages or injuries to persons, damages to property, losses, liens, causes of
action, suits, judgments and expenses (including without limitation,
consultants' and attorneys' fees) of any nature, kind or description of any
person or entity directly or indirectly arising out of, caused by or resulting
from (in whole or in part) (i) Tenant's construction of or use, occupancy or
enjoyment of the Premises; (ii) any activity, work or things done, permitted or

                                      -8-
<PAGE>   9

suffered by Tenant and its agents or employees in or about the Premises; or
(iii) any breach or default on Tenant's part under the covenants, terms and
conditions of this Lease, or any act, omission, willful misconduct or negligence
of Tenant, or any officer, agent, employee, guest, licensee or invitee of
Tenant; even if such liabilities are caused solely or in part by the ordinary
negligence of Landlord or any other Indemnitee, but not to the extent that such
liabilities are caused by the gross negligence or willful misconduct of Landlord
or any other Indemnitee. Tenant waives all claims in respect of any of the
foregoing liabilities against Landlord. Tenant shall give prompt notice to
Landlord in case of casualty or accidents in the Premises. In the event of
failure by Tenant to fully perform hereunder, Landlord may at its option and
without relieving Tenant of its obligations hereunder, so perform, but all costs
and expenses so incurred by Landlord in such event shall be reimbursed by Tenant
to Landlord.

12.      HAZARDOUS MATERIALS; HYDROGEN.

         a. Hazardous Material. Except as set forth on EXHIBIT C attached hereto
and incorporated herein by reference, Tenant shall not use, generate,
manufacture, produce, store, release, discharge, or dispose of, on, in, under or
about the Premises, or transport to or from the Premises, any Hazardous Material
(as defined in EXHIBIT C) or allow its agents, employees, contractors,
licensees, invitees or any other person or entity (collectively, "Tenant's
Agents") to do so. The schedule of Hazardous Materials attached to EXHIBIT C may
be amended from time to time as evidenced by the initials of both Landlord and
Tenant, showing the date of the amended schedule.

         b. Use of Hydrogen. Tenant shall not cause or permit hydrogen to be
used in any location on the Premises except for the room now designated as Room
223 (the "Hydrogen Lab").

         c. Disposal of Waste. Tenant shall comply with all federal, state and
local laws, orders, rules and regulations in disposing of its waste products.
Notwithstanding the foregoing, no Hazardous Materials may be released,
discharged or disposed of at the Premises, including into the water or sanitary
sewer system servicing the Premises. Tenant shall cause any and all Hazardous
Materials to be removed from the Premises, and to be removed and transported
solely by duly licensed handlers to duly licensed facilities for final disposal
of such materials and wastes.

13.      INSURANCE.

         Tenant shall, at Tenant's expense, maintain during the Term of this
Lease the following insurance:

         a. Commercial general liability, bodily injury and property damage
comprehensive coverage insuring against injury, death or property damage, with a
combined single limit coverage of not less than $3,000,000.00, and with a
maximum deductible of not more than

                                      -9-
<PAGE>   10

$10,000.00, which shall include a provision for contractual liability coverage
insuring Tenant for the performance of its indemnity obligations set forth in
this Lease.

         b. All risk personal property insurance for the full replacement value
of all fixtures, equipment, furniture and inventory on the Premises.

         c. All risk property insurance covering Building AC-1 for the full
replacement value of Building AC-1 and all fixtures attached thereto.

         d. Worker's compensation insurance to the statutory limit and
employer's liability insurance to the limit of $500,000.00 per occurrence.

Insurance required hereunder shall be provided by companies with a Best's
Insurance Guide Rating of "A" or better. Tenant shall deliver to Landlord copies
of insurance policies required herein or certificates evidencing the existence
and amounts of such insurance with loss payable clauses satisfactory to Landlord
prior to occupancy of the Premises, and shall provide to Landlord copies of all
renewals thereof. No policy shall be cancelable or subject to material change or
reduction of coverage without 60 days' prior written notice to Landlord, and the
certificate shall so state. All such policies shall be written as primary
policies not contributing with and not in excess of coverage which Landlord may
carry. Landlord shall be named as an additional insured on all policies required
herein. Landlord shall not be responsible for, and Tenant releases and
discharges Landlord from, and Tenant further waives any right of recovery from
Landlord for, any loss from business interruption or loss of use of the Premises
suffered by Tenant in connection with Tenant's use or occupancy of the Premises,
even if such loss is caused solely or in part by the negligence of Landlord.

14.      SUBROGATION.

         As long as their respective insurers so permit, Landlord and Tenant
hereby mutually waive their respective rights of recovery against each other for
any loss or damage to property insured by fire, extended coverage or any other
property insurance policies existing for the benefit of the respective parties.
The foregoing waiver shall be in force only if both parties' insurance policies
contain a clause providing that such a waiver shall not invalidate the insurance
and such a policy can be obtained without additional premiums.

15.      PARKING.

         Landlord reserves the right, with reasonable notice to Tenant, to
change the entrances, exits, traffic lanes and the boundaries and locations of
parking areas for the Amgen Complex. Based on a pro rata allocation, Tenant is
permitted to use up to 40 parking spaces in the general parking area. Such
spaces shall be designated by Landlord.

                                      -10-
<PAGE>   11

16.      LIMITED LIABILITY.

         Landlord shall not be liable for any loss or damage resulting from (a)
fire, explosion, falling plaster, steam, gas, electricity, water or rain; (b)
the pipes, appliances or plumbing works in the Amgen Complex; (c) the roof,
street, subsurface; (d) any variation or interruption of utility services; (e)
theft; or (f) any other cause whatsoever, unless due to the gross negligence of
Landlord. Tenant shall look solely to the Premises for the recovery of any
judgment against Landlord. Landlord and its shareholders, directors and officers
shall not be personally liable for any judgment.

17.      ASSIGNMENT AND SUBLETTING.

         Tenant shall not assign this Lease or sublet any part of the Premises
without the prior written consent of Landlord, which consent shall not be
unreasonably withheld. Any attempted assignment or subletting without Landlord's
prior written consent shall be wholly void and shall constitute a breach of this
Lease. Acceptance of Rent by Landlord from anyone other than Tenant shall not be
construed as a release of Tenant from any obligation or liability under this
Lease. The consent of Landlord to an assignment or underletting shall not be
construed to relieve Tenant from obtaining the written consent of Landlord to
any further assignment or underletting. If any rents or other sums received by
Tenant under any approved sublease are in excess of the Rent payable by Tenant
under this Lease (prorated for a sublease of less than 100% of the Premises), or
if any additional consideration is paid to Tenant by any assignee under any
assignment, then 50% of such excess Rents under any sublease or such additional
consideration under any assignment shall be paid by Tenant to Landlord as
Additional Rent hereunder within ten days after Tenant receives the same.

18.      DAMAGE BY CASUALTY.

         a. Subject to Sections 10 (a), 18 (b) and (c), in the event the
Premises is damaged by fire or other casualty, Landlord shall repair such damage
promptly and diligently. This Lease shall remain in full force and effect.

         b. If the damage to the Premises exceeds 50% of its value in Landlord's
reasonable determination, or if the damage is so extensive that Landlord shall
decide in its sole discretion to demolish it, then Landlord may elect to
terminate this Lease by delivering written notice to Tenant within 30 days
following such fire or other casualty.

         c. Landlord shall not be required to make any repairs or replacements
of any leasehold improvements, fixtures, or other personal property of Tenant.

19.      EMINENT DOMAIN AND CONDEMNATION.

         a. If such portion of the Premises as shall be reasonably required for
the conduct of Tenant's business shall be taken or appropriated by any public or
quasi-public authority under the power of eminent domain, either party hereto
shall have the right, at its option, within 60 days after notice of said taking,
to terminate this Lease upon 30 days' written notice or the date of the

                                      -11-
<PAGE>   12

taking, whichever occurs first. In case of a taking of part of the Premises
which leaves the remainder of the Premises reasonably satisfactory for the
continued conduct of Tenant's business, Landlord shall restore the Premises to
comparable condition, to the extent possible, and Rent shall be equitably
reduced based on any reduction in floor area of the Premises.

         b. In the event of any taking, Landlord shall be entitled to any and
all awards and/or settlements which may be given and Tenant shall have no claim
against Landlord for the value of any unexpired term of this Lease. Tenant shall
have the right to claim from the condemning authority a separate award for
damage to Tenant's business, a claim for fixtures and furnishings and relocation
expenses.

20.      ENTRY BY LANDLORD.

         Landlord reserves the right, with 24-hour advance notice given during
normal business hours, to enter the Premises during normal business hours to
access the BMS equipment room on the second floor of the Premises, to inspect
the Premises, to submit the Premises to prospective purchasers, lenders or
tenants, to post notices of non-responsibility, to post notices of Tenant's
failure to comply with this Lease, or to repair the Premises, without abatement
of Rent, and may for that purpose erect scaffolding and other necessary
structures where reasonably required; provided that the entrance to the Premises
shall not be unreasonably blocked. Tenant hereby waives any claim for damages to
Tenant's business, any loss of occupancy or quiet enjoyment of the Premises, and
any other loss occasioned thereby. Landlord shall retain a key to the Premises,
excluding Tenant's vaults, safes and files, and Landlord may open said doors in
an emergency, without any notice or liability to Tenant except for failure to
exercise due care for Tenant's property. Any entry to the Premises by Landlord
shall not be construed to be a forcible or unlawful entry into the Premises, or
an eviction of Tenant from the Premises.

21.      DEFAULT BY TENANT.

         a. Event of Default Defined. The occurrence of any one or more of the
following events shall constitute a default and breach of this Lease by Tenant:

                  i. The failure by Tenant to make any payment of Rent or any
other payment required to be made by Tenant hereunder, as and when due.

                  ii. The failure by Tenant to observe or perform any of the
covenants, conditions or provisions of this Lease (excluding any monetary
payment) to be observed or performed by Tenant.

                  iii. The making by Tenant of any general assignment for the
benefit of creditors; or the filing by or against Tenant of a petition to have
Tenant adjudged a bankrupt, or a petition of reorganization under any law
relating to bankruptcy unless, in the case of a petition filed against Tenant,
the same is dismissed within 60 days; or the appointment of a trustee or a
receiver to take possession of substantially all of Tenant's assets located at
the Premises or of

                                      -12-
<PAGE>   13

Tenant's interest in this Lease, where possession is not restored to Tenant
within 30 days; or the attachment, execution or other judicial seizure of
substantially all of Tenant's assets located at the Premises, or of Tenant's
interest in this Lease, where such seizure is not discharged within 30 days.

                  Tenant shall have an opportunity to cure a default under
subsection (a)(ii) above for a period of five business days after the due date
for such payment. Tenant shall have an opportunity to cure a default under
subsection (a)(iii) above for a period of 30 days after written notice by
Landlord to Tenant; provided that if the nature of Tenant's default is such that
more than 30 days is reasonably required for its cure, then Tenant must commence
such cure within said 30-day period and thereafter diligently prosecute such
cure to completion.

         b. Remedies. In the event of any such default or breach by Tenant,
Landlord may at any time thereafter, in its sole discretion, with or without
notice or demand and without limiting Landlord in the exercise of a right or
remedy which Landlord may have by reason of such default or breach:

                  i. Reenter and attempt to relet or take possession pursuant to
legal proceedings and remove all persons and property from the Premises. In such
event, Landlord may from time to time make such alterations and repairs as may
be necessary in order to relet the Premises or any part thereof for such term
(which may be for a term extending beyond the term of this Lease) and at such
Rental and upon such other terms and conditions as Landlord in its sole
discretion may deem advisable. Upon each such reletting, all rentals received by
Landlord from such reletting shall be applied: first, to the payment of any
costs and expenses of such reletting, including reasonable alterations and
improvements to the Premises, reasonable brokerage fees and reasonable
attorneys' fees; second, the payment of any indebtedness other than Rent due
hereunder from Tenant to Landlord; third, the payment of Rent due and unpaid
hereunder; and the residue, if any, shall be held by Landlord and applied to
payment of future Rent as the same may become due and payable hereunder. If such
Rentals received from such reletting during any month are less than that to be
paid during that month by Tenant hereunder, Tenant shall pay any cash deficiency
to Landlord. Such deficiency shall be calculated and paid monthly. No such
reentry or taking possession of the Premises by Landlord shall be construed as
an election on its part to terminate this Lease unless a notice of such
intention be given to Tenant or unless the termination thereof be decreed by a
court of competent jurisdiction. Notwithstanding any such reletting without
termination, Landlord may at any time thereafter elect in writing to terminate
this Lease for such previous breach.

                  ii. Terminate this Lease, in which case Tenant shall
immediately surrender possession. In addition to any other remedies which
Landlord may have, it shall have the right to recover from Tenant (a) as
liquidated damages for loss of bargain, and not as a penalty, an amount equal to
the aggregate amount of Rent and other charges equivalent to Rent reserved in
this Lease for the remainder of the Term, above the reasonable rental value of
the Premises; and (b) all other damages and expenses, including reasonable
attorneys' fees and the cost of recovering the Premises, that Landlord has
sustained because of Tenant's default. Tenant shall

                                      -13-
<PAGE>   14

pay upon demand all Landlord's costs, charges and expenses, including fees of
counsel, whether or not suit is filed, incurred in connection with the recovery
under this Lease or for any relief against Tenant.

22.      DEFAULT BY LANDLORD.

         Landlord shall not be in default unless Landlord fails to perform its
obligations within a reasonable time, but in no event later than 30 days after
written notice by Tenant to Landlord; provided that if the nature of Landlord's
obligation is such that more than 30 days are required for performance, then
Landlord shall not be in default if Landlord commences performance within such
30-day period and thereafter diligently prosecutes the same to completion.
Tenant shall have the right to terminate this Lease as a result of default
caused by Landlord's intentional wrongdoing or gross negligence if such default
is not cured in accordance with the preceding sentence.

23.      SUBORDINATION AND ATTORNMENT.

         This Lease is subordinate to any mortgage or deed of trust now or
hereafter placed on the Premises and to any renewal, modification,
consolidation, replacement or extension of such mortgage or deed of trust. This
clause shall be self-operative, and no further instrument of subordination shall
be required. Within five days after written request by Landlord, Tenant shall
execute any documents which may be necessary or desirable to effectuate the
subordination of this Lease. In the event such documentation is not so delivered
by Tenant or required herein, Landlord shall have the right to deliver such
documentation on Tenant's behalf, and Tenant designates Landlord as its
attorney-in-fact in providing such statement.

24.      BROKERS.

         Tenant warrants that it has had no dealings with any real estate broker
or agents in connection with the negotiation of this Lease.

25.      NOTICE.

         All notices shall be in writing sent by either (i) nationally
recognized overnight courier, (ii) certified mail, postage prepaid, return
receipt requested, or (iii) by facsimile; addressed as set forth below, or to
such other place as either party may designate by notice:

              To Landlord at:           Amgen Inc.
                                        One Amgen Center Drive
                                        Thousand Oaks, California  91320
                                        Attn:    Manager Corporate Real Estate
                                        Facsimile No.: (805) 447-6945

                                      -14-
<PAGE>   15
              With Copy to:             Amgen Inc.
                                        One Amgen Center Drive
                                        Thousand Oaks, California 91320
                                        Attn:    John O'Connor, Esq.
                                        Facsimile No.: (805) 499-8011

              To Tenant at:             Array BioPharma Inc.
                                        1885 33rd Street Building AC-1
                                        Boulder, Colorado 80301-2505
                                        Attn:    David Snitman
                                        Facsimile No.:
                                                       -----------------

Notice shall be deemed given upon posting of same with the overnight courier
service or in an official depository of the United States Postal Service or upon
completed transmission of same by facsimile machine, provided that no notice of
either party's change of address shall be effective until 15 days after the
addressee's actual receipt thereof.

For matters relating solely to the facilities located on the Premises, Tenant
should first contact Andy Graziano of Amgen, at telephone number 401-2834.

26.      ESTOPPEL STATEMENT.

         Tenant shall execute, acknowledge and deliver to Landlord, within five
business days after receipt of Landlord's written request therefor, a statement
in writing (a) certifying that this Lease is unmodified and in full force and
effect (or, if modified, stating the nature of such modification and certifying
that this Lease as so modified is in full force and effect); (b) acknowledging
that there are not, to Tenant's knowledge, any uncured defaults on the part of
the Landlord hereunder, or specifying such defaults if any are claimed; and (c)
setting forth the date of commencement and expiration of the Term hereof. Any
such statement may be relied upon by the prospective purchaser or encumbrancer
of the Premises or the Amgen Complex. In the event such statement is not so
delivered by Tenant as required herein, Landlord shall have the right to deliver
such statement on behalf of Tenant, and Tenant designates Landlord as its
attorney-in-fact in providing such statement.

27.      GENERAL PROVISIONS.

         a. The waiver by Landlord of any term, covenant or condition herein
contained shall not be deemed to be a waiver of any subsequent breach. The
acceptance of Rent shall not be deemed to be waiver of any default by Tenant.

         b. The headings to the section of this Lease shall have no effect upon
the construction or interpretation of any part hereof.

         c. Time is of the essence.

                                      -15-
<PAGE>   16

         d. The covenants and conditions herein contained bind the heirs,
successors, executors, administrators and permitted assigns of the parties
hereto.

         e. Neither Landlord nor Tenant shall record this Lease.

         f. Upon Tenant's paying the Rent reserved hereunder and observing and
performing all of the covenants, conditions and provisions on Tenant's part to
be observed and performed hereunder, Tenant shall have quiet possession of the
Premises for the entire Term hereof, subject to all the provisions of this
Lease.

         g. No remedy or election hereunder shall be deemed exclusive but shall,
whenever possible, be cumulative with all other remedies at law or in equity.

         h. This Lease shall be governed by the laws of the State of Colorado.

         i. Anything to the contrary herein notwithstanding, in the event of any
litigation or arbitration between Landlord and Tenant arising out of this Lease,
the court or arbitrator shall award to the prevailing party all reasonable costs
and expenses, including costs of investigation, settlement, expert witnesses and
reasonable attorneys' fees and disbursements.

         j. In the event of any sale of the Premises or the Amgen Complex by
Landlord, Landlord shall be relieved of all liability hereunder occurring
thereafter. The purchaser shall be deemed to have assumed and agreed to carry
out any and all of the covenants and obligations of the Landlord under this
Lease. As a condition to any sale of the Premises by Landlord, Landlord shall
cause the purchaser at or prior to the closing of such sale, to enter into a
Non-disturbance and Attornment Agreement with Tenant, in substantially the same
form attached hereto as EXHIBIT D .

         k. This Lease contains all of the agreements of the parties hereto with
respect to any matter covered or mentioned in this Lease, and no prior
agreements or understandings pertaining to any such matters shall be effective
for any purpose. No provision of this Lease may be amended or added to except by
an agreement in writing signed by the parties hereto or their respective
successors in interest.

         l. This Lease and the obligations of the Tenant hereunder shall not be
affected or impaired because the Landlord is unable to fulfill any of its
obligations hereunder or is delayed in doing so, if such inability or delay is
caused by reason of strike, labor troubles, extreme weather conditions or acts
of nature, or any other cause beyond the reasonable control of the Landlord.

         m. Any provision of this Lease which shall prove to be invalid, void,
or illegal shall in no way affect, impair or invalidate any other provision
hereof and such other provision shall remain in full force and effect.

                                      -16-
<PAGE>   17

         n. Tenant shall provide its most recent financial statement to Landlord
within 15 days of request.

         o. Each person(s) signing this Lease as an officer of Tenant represents
to Landlord that such person(s) is/are authorized to execute this Lease without
the necessity of obtaining any other signature of any other officer or partner,
that the execution of this Lease has been authorized by the board of directors
of the corporation and that this Lease is fully binding on Tenant. Landlord
reserves the right to request evidence of the approval of this Lease and
authorization of Tenant's signatories to bind Tenant, which evidence shall be
satisfactory in form and content to Landlord and its counsel. Tenant hereby
represents to Landlord that Tenant is duly incorporated, and in good standing in
the State of Delaware, and that Tenant is not a subsidiary of any other entity.

         p. This Lease may be executed in one or more counterparts, each of
which will be deemed an original, and all of which together will constitute one
and the same instrument.

                                      -17-
<PAGE>   18

IN WITNESS WHEREOF, the parties hereto have executed this Lease as of the date
first above written.

LANDLORD:                                    TENANT:

AMGEN INC.,                                  ARRAY BIOPHARMA INC.,
a Delaware corporation                       a Delaware corporation

By:      /s/                                 By:     /s/ DAVID SNITMAN
         ---------------------------                 ---------------------------
Its:     Chief Financial Officer             Its:    Chief Operating Officer
         ---------------------------                 ---------------------------

         By:                                         By:
             -----------------------                     -----------------------
                   [TITLE]                                      [TITLE]

<PAGE>   19

                                    EXHIBIT A
                                TO LEASE BETWEEN
                                   AMGEN INC.
                                       AND
                              ARRAY BIOPHARMA INC.

                             DESCRIPTION OF PREMISES

Building:      Amgen Building AC-1 with the address of 1885 33rd Street,
               Boulder, Colorado

Fixtures:      Those fixtures attached to the Premises as of the Commencement
               Date.

Parking:       Those spaces designated for Tenant's parking pursuant to Section
               15 of this Lease.

                                      A-1

<PAGE>   20

                                    EXHIBIT B
                                TO LEASE BETWEEN
                                   AMGEN INC.
                                       AND
                              ARRAY BIOPHARMA INC.

                                  RENT SCHEDULE

A.       INITIAL TERM RENT

<TABLE>
<CAPTION>
                                     Square          Rate per            Annual               Monthly
         Period                       Feet           Sq. Foot           Base Rent            Base Rent
         ------                     --------         --------           ---------            ---------
<S>                                 <C>              <C>                <C>                  <C>
7/15/98 - 7/14/01                   22,458            $22/yr.            $494,076            $41,173
</TABLE>

B.       EXTENSION TERM RENT

Rent for each additional year shall be adjusted in accordance with the
percentage change in the Denver-Boulder Consumer Price Index for All Urban
Consumers from the most recent twelve-month period (the sum of the last two
published semiannual reports as of 7/15/01 and 7/15/02 respectively) over the
prior twelve-month period; provided, however, that there shall be no negative
adjustment. Notwithstanding the foregoing sentence, any annual Rent increase
will be subject to a 3% minimum adjustment and a 5% maximum adjustment per year.

                                      B-1

<PAGE>   21

                                    EXHIBIT C
                                TO LEASE BETWEEN
                                   AMGEN INC.
                                       AND
                              ARRAY BIOPHARMA INC.

                               HAZARDOUS MATERIALS

1.       USE

         In addition to the provisions set forth in Section 12 of the Lease, the
         following terms and conditions shall apply:

         1.1      Permitted Hazardous Materials. Notwithstanding the provisions
                  of Section 12 of the Lease, Tenant shall be permitted to use
                  and store in, and transport to and from, the Premises,
                  Hazardous Materials so long as: (a) each of the Hazardous
                  Materials is used or stored in, or transported to and from,
                  the Premises only to the extent necessary for Tenant's
                  operation of its business at the Premises; and (b) the
                  conditions set forth in 1.3 through 1.8 hereof are strictly
                  complied with. The right to use and store in, and transport to
                  and from, the Premises the Hazardous Materials is personal to
                  Tenant and may not be assigned or otherwise transferred by
                  Tenant without the prior written consent of Landlord, which
                  consent may be withheld in Landlord's sole discretion.
                  Landlord agrees that it will not disclose and will hold in
                  confidence any and all of the information contained in the
                  Documents and Plans (as defined below), and other matters of a
                  confidential nature brought to Landlord's attention as being
                  confidential during the Term of this Lease, whether in written
                  or oral form.

         1.2      Compliance with Environmental Laws. Tenant shall comply with
                  and shall cause Tenant's Agents to comply with, and shall keep
                  and maintain the Premises and cause Tenant's Agents to keep
                  and maintain the Premises, in compliance with all
                  Environmental Laws (as defined in Section 1.8 below). Neither
                  Tenant nor Tenant's Agents shall violate, or cause or permit
                  the Premises to be in violation of, any Environmental Laws.

                  Tenant shall, at its own expense and prior to Tenant's use and
                  occupancy of the Premises, procure, maintain in effect and
                  comply with all conditions of any and all permits, licenses
                  and other governmental and regulatory approvals required for
                  Tenant's use of the Premises.

                  Tenant agrees to provide Landlord with: (a) a copy of any
                  Hazardous Material management plan or similar document
                  required by any federal, state or local governmental or
                  regulatory authority to be submitted by Tenant; (b) copies of
                  all permits, licenses and other governmental and regulatory
                  approvals with respect to

                                       C-1

<PAGE>   22

                  the use of Hazardous Materials, including without limitation
                  Tenant's identification number from the Environmental
                  Protection Agency; (c) copies of hazardous waste manifests
                  reflecting the legal and proper disposal of all Hazardous
                  Materials removed from the Premises; and (d) copies of all
                  reports, studies and written results of tests or inspections
                  concerning the Premises with respect to Hazardous Materials,
                  including, without limitation, the "Plans" hereinafter defined
                  (collectively "Documents"). Tenant shall deliver all Documents
                  to Landlord promptly following the earlier of (i) Tenant's
                  submission of such Documents to the requesting governmental
                  agency, or (ii) Tenant's receipt of such Documents (Tenant
                  hereby agreeing that it shall exercise diligent efforts to
                  expeditiously obtain copies of any such Documents known by
                  Tenant to exist).

         1.3      Routine Monitoring and Delivery of Plans. Upon commencing any
                  activity involving Hazardous Materials on the Premises, and
                  continuing thereafter throughout the Term of this Lease,
                  Tenant shall initiate and maintain the following systems to
                  ensure the routine monitoring of the levels of Hazardous
                  Materials which may be present on, under or about the Premises
                  or properties adjoining or in the vicinity of the Premises as
                  the result of the activities of Tenant or Tenant's Agents and
                  to ensure continued compliance with the procedures and
                  regulations concerning the handling, storage, use and disposal
                  of Hazardous Materials set forth in the following
                  (collectively, "Plans"): (a) each permit, license or other
                  governmental or regulatory approval with respect to the use of
                  Hazardous Materials, (b) each Hazardous Materials management
                  plan or similar document required by any federal, state, or
                  local governmental or regulatory entity, (c) each plan for
                  handling and disposing of Hazardous Materials necessary to
                  comply with Environmental Laws prepared by or on behalf of
                  Tenant or Tenant's Agents (whether or not required to be
                  submitted to a governmental agency). Copies of the Plans shall
                  be appended from time to time throughout the Term of this
                  Lease as such Plans are developed, as Attachment 1 hereto
                  attached to this Exhibit C.

         1.4      Notice to Landlord. Tenant shall give prompt written notice to
                  Landlord of:

                  (a)      any proceeding or inquiry by, notice from, or order
                           of any governmental authority with respect to the
                           presence of any Hazardous Material on, under or about
                           the Premises or the migration thereof from or to
                           other property;

                  (b)      all claims made or threatened by any third party
                           against Tenant or the Premises relating to any loss
                           or injury resulting from any Hazardous Materials;

                  (c)      any significant spill, release, discharge or disposal
                           (other than routine off-site disposal) of Hazardous
                           Materials that occurs with respect to the Premises or
                           operations at the Premises by Tenant or Tenant's
                           Agents;

                                       C-2

<PAGE>   23

                  (d)      all materials of which Tenant is required to give
                           notice pursuant to any Environmental Laws; and

                  (e)      Tenant's discovery of any occurrence or condition on,
                           under or about the Premises or any real property
                           adjoining or in the vicinity of the Premises that
                           could cause the Premises to be subject to any
                           restrictions on the ownership, occupancy,
                           transferability or use of the Premises under any
                           Environmental Laws.

                  1.4.1    Landlord's Right to Inspect. If Landlord has reason
                           to believe that Tenant is not in compliance with the
                           material terms of this Exhibit C, in addition to
                           Landlord's other rights and remedies pursuant to this
                           Lease, Landlord and its representative shall have the
                           right, upon five days' written notice, to enter the
                           Premises and to: (i) conduct appropriate testing,
                           monitoring and analysis for Hazardous Materials; (ii)
                           review any documents, materials, inventory, financial
                           data or notices or correspondence to or from private
                           parties or governmental or regulatory authorities in
                           connection therewith; and (iii) review all storage,
                           use, transportation and disposal facilities and
                           procedures associated with the storage, use,
                           transportation and disposal of Hazardous Materials
                           (collectively, "Inspection"). In the event that
                           Landlord prepares a written report of its inspection,
                           it agrees to provide Tenant a copy thereof, on
                           condition that Tenant shall have no right whatsoever
                           to rely upon any information contained in any such
                           report for any purpose of Tenant.

         1.5      Landlord's Right to Participate. Landlord shall have the right
                  to join and participate in, as a party if it so elects, any
                  legal proceedings or actions affecting the Premises initiated
                  in connection with any Environmental Law and have its
                  reasonable attorneys' fees in connection therewith paid by
                  Tenant. In addition, Tenant shall not take any remedial action
                  in response to the presence of any Hazardous Materials in,
                  under, or about the Premises (except in the case where loss of
                  life or substantial property or environmental damage is
                  imminent or immediate action is required by any governmental
                  entity, in which event Tenant shall take immediate remedial
                  action), nor enter into any settlement agreement, consent
                  decree or other compromise in respect to any claims relating
                  to any Hazardous Materials in any way connected with the
                  Premises, without first notifying Landlord of Tenant's
                  intention to do so and affording Landlord ample opportunity to
                  appear, intervene or otherwise appropriately assert and
                  protect Landlord's interest with respect thereto.

         1.6      Tenant's Indemnity. Tenant shall protect, defend (with counsel
                  satisfactory to Landlord), indemnify and hold harmless
                  Landlord, its directors, officers, employees, agents,
                  successors and assigns (the "Indemnified Parties") from and
                  against any and all claims, fines, judgments, penalties,
                  losses, damages, costs,

                                       C-3

<PAGE>   24

                  expenses or liability (including reasonable attorneys' fees,
                  reasonable consultants' fees and costs) (collectively or
                  individually, the "Claims") directly or indirectly arising out
                  of or attributable to the use, generation, manufacture,
                  production, storage, release, threatened release, discharge,
                  disposal, transportation to or from, or presence of any
                  Hazardous Material on, in, under or about the Premises
                  (collectively, a "Release"), regardless of whether such Claims
                  are caused or contributed to by the gross negligence, active
                  or passive, of an Indemnified Party, and so long as such
                  Claims arose during the Term of this Lease or can be
                  attributed to Tenant's occupancy or use of the Premises
                  including, without limitation: (a) all foreseeable
                  consequential damages, including, without limitation, loss of
                  rental income and diminution in property value; and (b) the
                  costs of any investigation, monitoring, removal, restoration,
                  abatement, repair, cleanup, detoxification or other
                  ameliorative work of any kind or nature (collectively
                  "Remedial Work") and the preparation and implementation of any
                  closure, remedial or other required plans. For purposes of
                  this Section 1.7, any acts or omissions of Tenant or Tenant's
                  Agents (whether or not they are negligent, intentional,
                  willful or unlawful) shall be strictly attributable to Tenant.
                  Tenant's obligations under this Section 1.6 shall survive the
                  expiration or earlier termination of this Lease.

                  In no event shall Landlord be responsible to Tenant for the
                  presence of Hazardous Materials in, on or about the Premises
                  to the extent caused or contributed to by any third party who
                  is not an Indemnified Party.

         1.7      Remedial Work. Upon any Release that does not comply with
                  Environmental Laws, Tenant shall, subject to Section 1.6,
                  promptly notify Landlord of such Release and shall, at its
                  sole expense and immediately after demand by Landlord,
                  commence to perform and thereafter diligently prosecute to
                  completion such Remedial Work as is necessary to restore the
                  Premises or any other property affected by such Release to a
                  condition that complies with all Environmental Laws and the
                  other provisions of this Lease. All such Remedial Work shall
                  be performed: (a) in conformance with the requirements of all
                  applicable Environmental Laws; (b) by one or more contractors,
                  approved in advance in writing by Landlord; and (c) under the
                  supervision of a consulting engineer approved in advance in
                  writing by Landlord (the "Consulting Engineer"). All costs and
                  expenses of such Remedial Work shall be paid by Tenant,
                  including, without limitation, the reasonable charges of such
                  Consulting Engineer and Landlord's reasonable attorneys' fees,
                  incurred in connection with the monitoring or review of such
                  Remedial Work. In the event Tenant shall fail to timely
                  commence, or cause to be commenced, or fail to diligently
                  prosecute to completion, such Remedial Work, Landlord may, but
                  shall not be required to, cause such Remedial Work to be
                  performed and all costs and expenses thereof, or incurred in
                  connection therewith, shall become immediately due and
                  payable.

                                       C-4

<PAGE>   25

                  Tenant's obligations under this Section 1.7 shall survive the
                  expiration or sooner termination of this Lease.

         1.8      Definitions. For purposes of this Exhibit "C", the following
                  definitions shall apply:

                  1.8.1    Hazardous Material. The term "Hazardous Material(s)"
                           shall include without limitation:

                           (a)      Those substances included within the
                                    definitions of "hazardous substances,"
                                    "hazardous materials," "toxic substances,"
                                    or "solid waste" under CERCLA (as defined
                                    below), RCRA (as defined below), and the
                                    Hazardous Materials Transportation Act, 49
                                    U.S.C. sections 1801 et seq., and in the
                                    regulations promulgated pursuant to said
                                    laws;

                           (b)      Those substances listed in the United States
                                    Department of Transportation Table (49 CFR
                                    172.101 and amendments thereto) or
                                    designated by the Environmental Protection
                                    Agency (or any successor agency) as
                                    hazardous substances (see, e.g., 40 CFR Part
                                    302 and amendments thereto);

                           (c)      Such other substances, materials and wastes
                                    which are or become regulated under
                                    applicable local, state or federal law, or
                                    the United States government, or which are
                                    or become classified as hazardous or toxic
                                    under federal, state, or local laws or
                                    regulations; and

                           (d)      Any material, waste or substance which is
                                    (i) petroleum, (ii) asbestos, (iii)
                                    polychlorinated biphenyls, (iv) designated
                                    as a "hazardous substance" pursuant to
                                    section 311 of the Clean Water Act of 1977,
                                    33 U.S.C. sections 1251 et seq. (33 U.S.C.
                                    section 1321) or listed pursuant to section
                                    307 of the Clean Water Act of 1977 (33
                                    U.S.C. section 1317), (v) flammable
                                    explosives, or (vi) radioactive materials.

                  1.8.2    Environmental Laws. "Environmental Laws" shall mean
                           any federal, state or local law, statute, ordinance,
                           or regulation now in effect or hereafter enacted
                           pertaining to health, industrial hygiene, or the
                           environmental conditions on, under or about the
                           Premises, including without limitation, the
                           Comprehensive Environmental Response, Compensation,
                           and Liability Act of 1980 ("CERCLA") as amended, 42
                           U.S.C. section 9601 et seq., and the Resource
                           Conservation and Recovery Act of 1976 ("RCRA") as
                           amended, 42 U.S.C. sections 6901 et seq.

                                       C-5

<PAGE>   26

2.       DECONTAMINATION PROCESS; SURRENDER

         In addition to Tenant's obligations pursuant to Section 10 of the
         Lease, Tenant shall, on the expiration or sooner termination of this
         Lease, surrender the Premises to Landlord, in the condition existing at
         the commencement of the Lease. Tenant acknowledges that Landlord has
         conducted a decontamination process on the Premises immediately prior
         to the Commencement Date, pursuant to state and local laws and
         regulations. After Landlord has completed the decontamination process,
         Landlord will provide Tenant with copies of all significant
         correspondence between Landlord and the State of Colorado regarding the
         process, including without limitation all test data submitted by
         Landlord to the State. Tenant shall perform a similar decontamination
         process on the Premises prior to the expiration or termination of this
         Lease, pursuant to state and local laws and regulations. If Tenant
         fails to surrender the Premises in accordance with this Section 2, the
         provisions of Section 1.6 of this Exhibit C shall apply, and Landlord
         shall have the right, but not the obligation, to appoint a consultant,
         at Tenant's reasonable expense, to conduct an investigation to
         determine whether any Hazardous Materials are located in or about the
         Premises, and to determine the corrective measures required to remove
         such Hazardous Materials. Tenant, at its expense, shall comply with all
         recommendations of such consultant. A failure by Landlord to appoint
         such a consultant shall in no way relieve Tenant of any of Tenant's
         obligations set forth in this Lease relating to Hazardous Materials,
         nor constitute a waiver of Landlord's rights under this Lease. Tenant's
         obligations under this Section 2 shall survive the expiration or
         earlier termination of this Lease.

3.       LESSOR'S USE OF CONSULTANTS

         All costs and expenses incurred by Landlord in retaining a consultant
         for any purpose in accordance with this Exhibit C shall become due and
         payable by Tenant, as Additional Rent, within 30 days after
         presentation by Landlord of an invoice therefor.

4.       EFFECT OF EXHIBIT C

         In the event of a conflict between the terms of this Exhibit C and the
         terms of the Lease, the terms of this Exhibit C shall control.

                                       C-6

<PAGE>   27

                                  ATTACHMENT 1
                         (ATTACHED TO AND MADE A PART OF
                    EXHIBIT C TO LEASE BETWEEN AMGEN INC. AND
                              ARRAY BIOPHARMA INC.)

                                      PLANS

                                       C-7

<PAGE>   28

                                    EXHIBIT D
                                TO LEASE BETWEEN
                                   AMGEN INC.
                                       AND
                              ARRAY BIOPHARMA INC.

                    NON-DISTURBANCE AND ATTORNMENT AGREEMENT

         THIS NON-DISTURBANCE AND ATTORNMENT AGREEMENT (this "Agreement"),
dated_________, 199__, is between ______________________________, a
________________________ ("Purchaser"), whose address is
__________________________ ____________________ and Array BioPharma Inc., a
Delaware corporation ("Tenant"), whose address is 1885 33rd Street, Building
AC-1, Boulder, Colorado 80301-2505.

                                    RECITALS

         A.       Tenant and Amgen Inc., a Delaware corporation ("Landlord")
                  entered into a certain Lease dated July ____, 1998 (the
                  "Lease") pursuant to which Tenant leases the premises known as
                  1885 33rd Street, Building AC-1, as more particularly
                  described in the Lease ("the Premises").

         B.       Section 27(j) of the Lease provides that Landlord shall cause
                  any purchaser of the Premises to enter into a non-disturbance
                  and attornment agreement with Tenant to provide Tenant certain
                  assurances during the pendency of the Lease.

         C.       Purchaser has offered to and is in the process of purchasing
                  the Premises from Landlord.

         D.       Tenant and Purchaser now desire to enter into such agreement
                  under the terms and conditions stated below.

                                    AGREEMENT

         NOW THEREFORE, in consideration of the mutual covenants, conditions,
and agreements hereinabove referred to and hereinafter contained, and for other
good and valuable consideration, the receipt and sufficiency of which the
parties hereby acknowledge, Tenant and Purchaser hereby agree as follows:

1.                If and when Purchaser obtains fee title to the Premises, and
                  on condition that Tenant is not in default under the terms of
                  the Lease:

                           (i) the Lease shall remain in full force and effect;

                                       D-1

<PAGE>   29

                           (ii) Tenant's rights and privileges under the Lease
                           and use, possession and enjoyment of the Premises
                           shall not be disturbed, interfered with, or
                           terminated by reason of such purchase of the
                           Premises;

                           (iii) upon notice that Purchaser has purchased the
                           Premises, Tenant agrees to attorn to Purchaser and
                           Purchasers agrees to accept Tenant's attornment as if
                           Purchaser were the landlord under the Lease; and

                           (iv) Tenant and Purchaser agree to perform all their
                           respective duties and obligations under the Lease for
                           the duration of the Lease Term.

2.                This Agreement shall be binding upon and inure to the benefit
                  of the parties hereto and their respective successors and
                  assigns, and shall be construed under and governed by the laws
                  of the State of Colorado.

3.                This Agreement may not be changed, altered, or modified except
                  in writing signed by both parties hereto.

                  This Agreement has been executed by the parties as of the date
                  first written above.

                                       TENANT:

                                           Array BioPharma Inc.,
                                           a Delaware corporation

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

                                           PURCHASER:

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

                                       D-2

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