Document:

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                                                   CONFIDENTIAL - EXECUTION COPY
                                                                   EXHIBIT 10.58

        CYSTIC FIBROSIS RESEARCH ALLIANCE AND COMMERCIALIZATION AGREEMENT

                                     BETWEEN

                         THE CYSTIC FIBROSIS FOUNDATION

                                       AND

                         AURORA BIOSCIENCES CORPORATION

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                            CYSTIC FIBROSIS RESEARCH
                    ALLIANCE AND COMMERCIALIZATION AGREEMENT

THIS AGREEMENT is entered into as of May 19, 2000 (the "Effective Date") by and
between the CYSTIC FIBROSIS FOUNDATION with a principal place of business at
6931 Arlington Road, Bethesda, Maryland 20814 ("CFF"), and AURORA BIOSCIENCES
CORPORATION, a Delaware corporation having offices at 11010 Torreyana Rd., San
Diego, California 92121 ("Aurora").

                                    RECITALS

WHEREAS, Aurora has expertise in the development of automated screening systems
and screening biologies used therein and has rights to certain intellectual
property related thereto; and

WHEREAS, Aurora has the scientific expertise and capacity to undertake the drug
discovery program contemplated herein; and

WHEREAS, CFF wishes to enter into this Agreement with Aurora to significantly
extend and expand an existing cystic fibrosis assay development and screening
project.

NOW, THEREFORE, in consideration of the foregoing premises and of the covenants,
representations and agreements set forth below, the parties agree as follows:

1    DEFINITIONS

The definitions used in this Agreement are attached in Exhibit 1.

2       THE COLLABORATION

        2.1     Collaboration Committee. The Collaboration Committee shall
                provide advice and support to the Steering Committee regarding
                scientific and technical aspects of the Collaboration. The
                Collaboration Committee will cooperate to prepare annually a
                detailed and updated Work Plan for each subsequent year of the
                Collaboration as provided in Exhibit 2.1 for the first year of
                the Collaboration, make recommendations on the allocation of
                funded FTEs at Aurora in accordance with this Agreement, and
                periodically review the progress of the Collaboration. In
                addition, the Collaboration Committee shall make good faith
                scientific and resource recommendations to the Steering
                Committee as set forth in this Agreement, help to determine
                scientific priorities for assay development and screening,
                technology development, genomics and bioinformatics initiatives,
                suggest changes in strategy or new areas for research, and
                identify to the Steering Committee projects that should be
                discontinued. Each party will appoint *** voting members to the
                Collaboration Committee within *** days of the Effective Date.
                Recommendations by the Collaboration Committee will be made by a
                simple majority of all voting members.

                The Collaboration Committee will request and require Aurora to
                provide a written summary of the research performed on an annual
                basis and such summary will be reviewed in good faith by the
                Collaboration Committee. The Collaboration Committee may
                recommend

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                approval of the Work Plan for each year of the Collaboration.
                The Collaboration Committee will meet in person, by telephone or
                videoconference at least *** times per year or more often as
                mutually agreed. Each party will pay its own expenses incurred
                in connection with participation at Collaboration Committee
                meetings. Each party will appoint one (1) of its Collaboration
                Committee representatives to be responsible for coordinating
                communications between the parties. Subgroups or subcommittees
                of the Collaboration Committee may be established and meet,
                either in person or by telephone or videoconference, more
                frequently on an "as needed" basis. As appropriate, the
                Collaboration Committee will make recommendations to the
                Steering Committee.

        2.2     Steering Committee. The Steering Committee will have overall
                management of finances and scientific oversight responsibility
                for the Collaboration using recommendations of the Collaboration
                Committee. The Steering Committee shall review and approve the
                Work Plan as it may be updated and amended from time to time and
                other recommendations of the Collaboration Committee, ensure
                that reasonable objectives of the Collaboration are pursued and
                monitored, that the science performed is of high quality, and
                that resources are appropriately acquired or used. With respect
                to financial management and scientific issues, the Steering
                Committee will attempt to mutually resolve issues that arise in
                the course of the Collaboration in a good faith manner. The
                Steering Committee will meet in person, by telephone or
                videoconference at least *** times per year or more often as
                mutually agreed. Each party will pay its own expenses incurred
                in connection with participation at Steering Committee meetings.
                Each party will appoint one (1) of its Steering Committee
                representatives to be responsible for coordinating
                communications between the parties. Each party will appoint ***
                voting members to the Steering Committee within *** days of the
                Effective Date. Decisions of the Steering Committee will be made
                by a simple majority of all members, ***.

        2.3     The Collaboration. The Collaboration will specifically focus on
                the discovery and preclinical development of novel therapeutics
                for CF. Subject to the parties' obligations herein, Aurora will
                use reasonable efforts during the Collaborative Period to
                perform the following in accordance with the Work Plan:

                2.3.1.  Develop at least *** high throughput or ultra-high
                        throughput CF Assays or CF-Related Assays for selected
                        CF Targets.

                2.3.2.  Conduct at least *** primary screens with CF Assays and
                        CF-Related Assays of at least *** to *** compounds per
                        screen using assays developed pursuant to Section 2.3.1,
                        the number of compounds used depending on the assay type
                        in accordance with the Work Plan, for a total of up to
                        *** datapoints ***, including controls, re-tests and
                        potency determinations which will constitute
                        approximately *** of such datapoints; provided, however
                        that no more than *** datapoints (generally in no less
                        than *** compound blocks for primary screening) will
                        require Aurora's *** technology. The parties may agree
                        in writing to screen additional compounds to generate
                        datapoints in excess of *** using Aurora's ***
                        technology at a price of *** dollars ($***) per ***
                        datapoints, and to generate datapoints in excess of ***
                        datapoints using Aurora's high or ultra high throughput
                        (UHTSS) technology at a price of *** dollars *** per ***
                        datapoints.

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                2.3.3.  Develop focused compound libraries of chemicals ***
                        pursuant to the Work Plan.

                2.3.4.  Provide follow-up chemical design and synthesis for Lead
                        expansion and optimization for an estimated *** Leads
                        selected from Validated Hits from primary screens using
                        assays developed pursuant to Section 2.3.1 and the Work
                        Plan and the parties agree to negotiate in good faith to
                        expand the Collaboration to pursue additional Leads if
                        the funding under Section 3.2.1 is insufficient for
                        further Lead development.

                2.3.5.  Develop ***assemble a *** assays relevant to each CF
                        Assay or CF-Related Assay as mutually agreed upon in
                        writing by the parties and pursuant to the Work Plan.

                2.3.6.  Profile Hits having desirable secondary functional assay
                        properties using in vitro assays available to Aurora
                        that are appropriate for one or more of the following:
                        metabolism, safety, toxicology and pharmacokinetics as
                        early in the Collaborative Period as reasonable. Profile
                        Validated Hits in in vivo tests for pharmacokinetics as
                        set forth in the Work Plan

                2.3.7.  Coordinate Lead prioritization, in conjunction with the
                        Collaboration Committee ***. Lead prioritization will be
                        based on ***.

                2.3.8.  Produce *** Development Candidates for CF Assays and
                        CF-Related Assays *** Development Candidates in total)
                        with profiles suitable for further in vivo testing and
                        entry into the drug development pipeline.

        2.4     The CF targets not currently specified in the Work Plan that may
                be subsequently proposed in writing by CFF after the Effective
                Date shall be CF Targets that CFF reasonably believes to be
                amenable for development for a high throughput screen using
                Aurora Technology. Aurora may reasonably request further
                information regarding the proposed CF Targets. Within *** days
                of first receiving such information, Aurora shall notify CFF in
                writing in the event that Aurora reasonably believes that the
                development of a CF Assay or CF-Related Assay based on the
                proposed CF Target is not consistent with Aurora's Third Party
                obligations or if Aurora believes that the development of a CF
                Assay or CF-Related Assay for a proposed CF Target would not
                reasonably be legally (e.g., patent infringement) feasible based
                on available information and that information provided by CFF.
                If Aurora declines to work on a CF Target proposed by CFF,
                Aurora will provide CFF with reasons for declining to work on
                the proposed CF Target based on the written opinion of outside
                counsel, to the extent that Aurora does not have to reveal
                Confidential Information of a Third Party, waive attorney client
                privilege or contravene an obligation to a Third Party.

        2.5     Staffing. In accordance with its best business practices for
                staffing to provide discovery services to large pharmaceutical
                companies, Aurora will provide *** to the Collaboration to
                endeavor to accomplish the reasonable objectives of the Work
                Plan. Aurora will propose a Collaboration Manager to the
                Steering Committee and subject to the approval of CFF, such
                approval not to be unreasonably withheld. ***. Aurora will use
                ***,

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                and if Aurora *** involved in the Collaboration *** in the
                Collaboration, Aurora will expeditiously use *** to *** with
                ***.

3       COMPENSATION TO AURORA

        3.1     Technology Access Fee. CFF will pay to Aurora a non-refundable
                and non-creditable technology access fee of *** dollars ($***),
                due on the Effective Date, and additional payments of ***
                dollars ($***) on the subsequent anniversaries of the Effective
                Date during the Collaborative Period.

        3.2     Research and Contract Services Payments.

                3.2.1   FTE Funding. Payments for FTE research support for assay
                        development, screening, technology development,
                        chemistry and project management (non-creditable,
                        non-refundable) for the Collaboration will be made by
                        CFF to Aurora, initially on the Effective Date (for year
                        1) and then on the first day of each quarter thereafter
                        in equal installments for each year during the
                        Collaborative Period in accordance with following table,
                        and as adjusted on an annual basis by the Biotech Index:

<TABLE>
<CAPTION>
           Year of Agreement      No. of FTEs      Research Funding Per Year
           -----------------      -----------      -------------------------
<S>                               <C>              <C>
           Year 1                      ***                  ***
           Year 2                      ***                  ***
           Year 3                      ***                  ***
           Year 4                      ***                  ***
           Year 5                      ***                  ***
</TABLE>

                Aurora will provide *** corresponding to the research performed
                under the Collaboration to CFF and the Steering Committee to
                facilitate monitoring of progress and expenditures. *** during
                the Collaborative Period and applied by Aurora with the approval
                of the Collaboration Committee and any *** at the end of the
                Collaborative Period ***.

                3.2.2.  Third Party Contract Services for In Vivo Testing and
                        Chemistry. In addition to the FTE funding payments as
                        described in Section 3.2.1 above, CFF will also make
                        non-creditable, non-refundable payments to Aurora for
                        the purchase by Aurora of contracted services for in
                        vivo testing, chemistry scale-up and synthesis to
                        support in vivo testing or additional chemistry
                        libraries (not including Sections 2.3.2 and 2.3.3) from
                        Third Parties necessary for the Collaboration and
                        approved by the Steering Committee, such payment to be
                        made by CFF to Aurora within *** days of receipt of
                        invoice (including back-up invoices and other supporting
                        detail) from Aurora that such expenses have been
                        incurred. It is estimated that the total cost of
                        contract services through the Collaborative Period will
                        be approximately *** dollars ($***) ***. This ***, for
                        the Collaboration, pursuant to Section 3.2.1.

                3.2.3   Third Party Services and Collaboration. From time to
                        time, during the Collaborative Period, Aurora may
                        determine that it is in the best interests of the
                        Collaboration to (i)

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                        subcontract certain services within the scope of the
                        Collaboration including the services set forth in
                        Section 3.2.2; (ii) access or license biological
                        materials, reagents, compounds and know-how useful for
                        the Collaboration from Third Parties, either academic or
                        commercial; (iii) obtain unusual reagents, materials or
                        instrumentation (collectively, "Collaboration Assets");
                        (iv) license technology not otherwise available to
                        Aurora; or (v) propose that additional Aurora FTE's are
                        necessary to accomplish the goals of the Collaboration,
                        which will not include payments by CFF pursuant to
                        Section 2.3.2 ***. Aurora will review with the
                        Collaboration Committee and report promptly to the
                        Steering Committee upon making such determination and,
                        if possible, at least *** days prior to the beginning of
                        each year during the Collaboration Period in which the
                        action resulting from such determination is proposed to
                        occur:

                        3.2.3.1 the nature of the Third Party services, licenses
                                or Collaboration Assets Aurora has determined
                                are appropriate;

                        3.2.3.2 such supporting material as is necessary to
                                allow the Steering Committee to fully understand
                                the need for such subcontracting, licensing,
                                Collaboration Assets, additional FTE's, and the
                                costs involved; and

                        3.2.3.3 whether Aurora proposes

                                3.2.3.3.1 that the cost of any such services,
                                          licenses or Collaboration Assets will
                                          be paid by Aurora from the payments
                                          made by CFF to Aurora hereunder; or

                                3.2.3.3.2 whether Aurora proposes that an
                                          additional payment by CFF will be
                                          necessary because Aurora's other
                                          activities and expenditures on the
                                          Collaboration will cause it to fully
                                          utilize such payments.

                        3.2.3.4 If Section 3.2.3.3.2 above is applicable or if
                                additional FTE's are proposed, the Steering
                                Committee shall determine whether ***.
                                Additional Aurora FTEs utilized within this
                                Collaboration will be charged to CFF at a rate
                                of *** dollars ($***) per year, as adjusted by
                                the ***.

                        3.2.3.5 If the Steering Committee determines in
                                accordance with Section 3.2.3 that Collaboration
                                Assets are to be acquired, Aurora shall *** of
                                the Collaboration; provided, however, that ***
                                such Collaboration Assets *** approved by the
                                Steering Committee) at the termination of the
                                Collaboration.

                        3.2.3.6 If the decision of the Steering Committee in
                                Section 3.2.3.4 would *** of the Collaboration
                                *** Third Party (i) the Steering Committee shall
                                fully consider whether the proposed transfer is
                                justified in reaching the goals of the
                                Collaboration by balancing the anticipated
                                benefits of such transfer and the availability
                                and cost of alternative means to obtain such
                                rights or services; and (ii) if a transfer of a
                                portion of downstream revenues is determined to
                                be appropriate, such transfer shall be shared
                                proportionately by the parties to the Agreement
                                in accordance with the agreed upon percentages
                                specified for sharing such benefits under
                                Sections 4.5.1 and 4.5.2 of this Agreement.

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                3.2.4   Screening of Third Party Compounds. During the
                        Collaborative Period CFF may, with the written consent
                        of Aurora ***, have Aurora screen chemicals provided by
                        CFF and obtained with written permission from Third
                        Parties ***. Such chemicals shall be provided to Aurora
                        in accordance with the provisions of Section 3.2.5. Such
                        chemicals supplied by CFF or Third Parties will be
                        provided to Aurora in appropriate amounts in *** at a
                        concentration of *** in a *** plate with *** wells of
                        test chemicals, or in a *** plate with *** wells of test
                        chemicals, or such other format as is mutually agreed by
                        the Collaboration Committee. Aurora agrees not to
                        transfer such chemicals to any other Third Party, or to
                        use them for any purpose other than screening assays
                        developed under the Collaboration. CFF will exercise
                        good faith efforts to obtain from each relevant Third
                        Party *** with such Third Party chemicals to Aurora by
                        CFF or such Third Party within *** of completion of such
                        screening *** to CFF by Aurora or a mutually agreed upon
                        time *** that can be used to determine ***. The parties
                        agree that *** obtain the right to *** Aurora from each
                        such Third Party and *** information to Aurora *** that
                        can be used to ***. Aurora will return or destroy unused
                        chemicals upon written notice from CFF.

                3.2.5   Development and Commercialization of Third Party
                        Compounds. Aurora, CFF and Third Party compound or
                        chemistry service suppliers (if any) will agree in
                        writing at the time of entering into any Third Party
                        agreement pursuant to Section 3.2.4 *** of Validated
                        Hits or Leads resulting from CF Assays or CF Related
                        Assays solely in the CF Field and/or the Pulmonary Field
                        under this Agreement, and that *** of Validated Hits or
                        Leads resulting from CF-Related Assays outside the CF
                        Field or the Pulmonary Field and commercial rights
                        thereto in accordance with Section 4.3. *** Aurora and
                        CFF will receive milestone and royalty payments or other
                        forms of consideration for rights to Development
                        Candidates or Products resulting from such Validated
                        Hits or Leads.

        3.3.    Research Milestones. In addition to the other payments in
                accordance with this Agreement and in consideration for
                achieving certain Collaboration objectives set forth below, CFF
                will pay to Aurora the following non-refundable, non-creditable
                research milestone payments:

                3.3.1   Payments for Assay Development. CFF will pay assay
                        development milestones to Aurora upon ***. The
                        characteristics of the assays and associated data
                        required for evaluation as a CF Assay or CF-Related
                        Assay will be made available to CFF and the Chemistry
                        Advisory Group. Such assay(s) will *** validation and
                        payment of such milestone. The milestone amount for the
                        *** is *** dollars ($***) to be paid by CFF within ***
                        days of notice by Aurora that such assay ***. The
                        parties anticipate, subject to a greater understanding
                        of the biology and chemistry of CF Targets by the
                        parties, that during the Collaborative Period *** CF
                        Assays or CF-Related Assays ***. New CF Targets under
                        consideration, and a schedule for CF Target development
                        and implementation in screening, are and will be
                        described in the Work Plan. Validation of CF Assays and
                        CF-Related Assays is subject to the approval of the
                        Steering Committee after recommendation of the
                        Collaboration Committee using guidelines described in
                        the Agreement and such approval will take no longer than
                        *** days. The first such assay is likely to be ***
                        September 9, 1999 between the parties.

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                3.3.2   Payments for Validated Hit Identification. CFF will pay
                        Validated Hit identification milestones to Aurora upon
                        the identification of each Validated Hit for a CF
                        Target, representing ***. The structures of Hits and
                        associated data will be made available solely to CFF and
                        the Chemistry Advisory Group *** as a Validated Hit.
                        Each such Validated Hit will *** identification and
                        payment of such milestone. The milestone amount for the
                        confirmation of each Validated Hit is:

                        *** dollars ($***) for *** Validated Hit for each of the
                        CF Targets;

                        *** dollars ($***) for *** Validated Hit for each of the
                        CF Targets; and

                        *** dollars ($***) for *** Validated Hit for each of the
                        CF Targets;

                        provided, however if CFF determines *** the screening
                        and compound characterization with *** CF Targets, upon
                        termination of the Collaboration, in addition to any
                        other payment due to Aurora in accordance with the terms
                        of this Agreement, CFF shall pay to Aurora the
                        difference, if any, between (1) the number of Validated
                        Hits multiplied by *** dollars ($***), but not to exceed
                        *** dollars ($***); and (2) the amount payable to Aurora
                        pursuant to this Section 3.3.2 without regard to this
                        provisio.

                        Such payments are to be paid to Aurora by CFF within ***
                        days of notice by Aurora of the confirmation of a
                        Validated Hit in accordance with this Agreement. The
                        parties anticipate, subject to a greater understanding
                        of the biology and chemistry of the CF Target by the
                        parties, that during the Collaborative Period a
                        sufficient number of Validated Hits will be generated to
                        produce *** Leads pursuant to Section 3.3.3.
                        Identification of each Validated Hit is subject to the
                        approval of the Steering Committee after recommendation
                        of the Collaboration Committee using guidelines
                        described in the Work Plan and such confirmation will
                        take no longer than *** days, or such longer period ***.

                3.3.3   Payments for Lead Identification. CFF will pay Lead
                        identification milestones to Aurora upon the
                        identification of each Lead for a CF Target,
                        representing a compound that is active on such CF
                        Target. The structures of Validated Hits and associated
                        data will be made available solely to CFF and the
                        Chemistry Advisory Group for evaluation as a Lead. Each
                        such Lead will not be made available by Aurora to CFF or
                        a Third Party in any physical form prior to such
                        identification and payment of such milestone. The
                        milestone amount for the identification of each Lead is
                        *** dollars ($***) to be paid to Aurora by CFF within
                        *** days of notice by Aurora of the confirmation of a
                        Lead. The parties anticipate, subject to a greater
                        understanding of the biology and chemistry of the CF
                        Target by the parties, that during the Collaborative
                        Period *** Leads will be identified. Identification of
                        each Lead is subject to the approval of the Steering
                        Committee after recommendation of the Collaboration
                        Committee using guidelines described in the Work Plan
                        and such confirmation will take no longer than *** days,
                        or such longer period ***.

                3.3.4   Payments for Development Candidate Identification. CFF
                        will pay Development Candidate identification milestones
                        to Aurora upon the *** for a CF Target, representing a
                        *** as a potential drug. The structures of Leads and
                        Derivatives and associated data will be

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                        made available solely to CFF and the Chemistry Advisory
                        Group for evaluation as a Development Candidate. Such
                        Development Candidate(s) will *** confirmation and
                        payment of such milestone. The milestone amount for the
                        identification of each Development Candidate is ***
                        dollars ($***) to be paid by CFF within *** days of
                        notice by Aurora of the confirmation of a Development
                        Candidate. The parties anticipate, subject to a greater
                        understanding of biology and chemistry by the parties,
                        that during the Collaborative Period and after the ***
                        anniversary of the Effective Date, *** Development
                        Candidates will be identified. Identification of each
                        Development Candidate is subject to the approval of the
                        Steering Committee after recommendation of the
                        Collaboration Committee using guidelines described in
                        the Work Plan and such confirmation will take no longer
                        than *** days, or such longer period ***.

                3.3.5   Milestone Arbitration. CFF and Aurora will use good
                        faith efforts to evaluate achievement of a milestone
                        event set forth in Section 3.3. *** milestones set forth
                        in Section 3.3 the parties will *** within *** after the
                        parties determine that an agreement between them cannot
                        be reached *** in this Agreement. CFF and Aurora will
                        use good faith efforts to *** within *** of such
                        disagreement. ***, the parties will arbitrate as set
                        forth in Section 10.14.

                3.3.6   Milestone Notification. Milestone notification by Aurora
                        will not occur prior to the completion of the approval
                        process as set forth in Sections 3.3.1 through 3.3.5.

4       COMMERCIALIZATION

        4.1     Development of Products for the CF Field. *** in the development
                and commercialization of Development Candidate(s), and CF
                Product(s), in the CF Field for the treatment of CF, ***, for
                which the milestones described in Section 3.3 and Section 4.4
                have been paid to Aurora; provided, however *** in writing and
                within *** days any prospective written agreement *** for the
                development and commercialization of Development Candidate(s),
                and CF Product(s), in the CF Field for the treatment of CF. Such
                *** will terminate with respect to a Development Candidate or CF
                Product after *** an agreement with a Third Party *** for the
                commercialization of such Development Candidate or CF Product
                for all of the CF Field, or *** years after the payment for the
                corresponding Development Candidate milestone pursuant to
                Section 3.3.3. After such date *** will continue *** the
                development and commercialization of Development Candidate(s),
                and Product(s) in the CF Field and *** will be required to ***
                to enter into a written agreement in the CF Field; provided,
                however that *** such written agreement must provide *** with no
                less than *** days or other period of time mutually agreed upon
                in writing to enter into a development and commercialization
                agreement ***. *** includes the notice of, *** as soon as
                reasonably possible, and the ***. It is anticipated that such
                development and commercialization will be conducted *** is not
                required to incur additional expense in this regard, although it
                may elect to do so. *** in accordance with this Agreement, to
                advance Development Candidate(s) and CF Product(s) in the CF
                Field as expeditiously as practicable into clinical development.

        4.2     Development of Products for the Pulmonary Field. *** the
                development and commercialization of Development Candidate(s),
                and Product(s) in the Pulmonary Field,

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                *** for which the milestones described in Section 3.3 and
                Section 4.4 have been paid; provided, however *** in writing and
                within *** days any prospective written agreement *** for the
                development and commercialization of Development Candidate(s),
                and CF Product(s) in the Pulmonary Field. Such *** will
                terminate with respect to a Development Candidate or CF Product
                after *** an agreement with a Third Party *** for the
                commercialization of such Development Candidate or CF Product
                for all of the CF Field (whether in conjunction with all or a
                portion of the Pulmonary Field), or *** years after the payment
                for the corresponding Development Candidate milestone pursuant
                to Section 3.3.3. After such date *** will continue *** the
                development and commercialization of Development Candidate(s),
                and Product(s) in the Pulmonary Field and *** will be required
                to *** to enter into a written agreement in the Pulmonary Field;
                provided, however that *** such written agreement must provide
                *** with no less than *** days or other period of time mutually
                agreed upon in writing to enter into a development and
                commercialization agreement ***. *** will have *** a written
                agreement *** for a Development Candidate or Product where such
                written agreement *** a *** and a ***. *** includes the notice
                of, *** as soon as reasonably possible, and the ***. It is
                anticipated that such development and commercialization in the
                Pulmonary Field will be conducted *** is required to incur
                additional expense in this regard, although it may elect to do
                so. ***

                will *** in accordance with this Agreement to advance
                Development Candidate(s) and Product(s) as expeditiously as
                practicable into development.

        4.3     Development of Products Outside both the CF Field and Pulmonary
                Field. *** the development and commercialization of Development
                Candidate(s) and Product(s), outside the CF Field, *** for which
                the milestones described in Sections 3.3 and 4.4 have been paid.
                It is anticipated that such development and commercialization
                will be conducted *** not required to incur additional expense
                in this regard, although it may elect to do so. *** use *** in
                accordance with this Agreement to advance Development
                Candidate(s) and Product(s) as expeditiously as practicable into
                development, and in any case within *** years after the payment
                of the milestone corresponding to the Development Candidate. If
                a commercialization partner or licensee has not been identified
                for any Development Candidate or Product for use outside the CF
                Field or Pulmonary Field within such *** years, all rights will
                *** for each such Development Candidate or Product.

        4.4     Milestones Paid to Aurora. In the event CFF and/or its
                licensees, licensors or collaborators succeeds in developing or
                commercializing Development Candidate(s) or Product(s) resulting
                from activities performed pursuant to this Agreement, CFF will
                pay non-refundable and non-creditable amounts to Aurora as set
                forth below:

                When a Development Candidate or Product for the CF Field reaches
                the following milestone events, CFF will promptly notify Aurora
                of same, and within *** days of such notification, CFF will pay
                Aurora the amount corresponding to such milestone.

<TABLE>
<CAPTION>
                Milestone Event                                     Amount ($US)
                ---------------                                     ------------
<S>                                                                 <C>
</TABLE>

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<TABLE>
<CAPTION>
<S>                                                                 <C>
                Initiation of Phase I Clinical Testing                  ***

                Initiation of Phase III Clinical Testing                ***

                Submission of an NDA                                    ***
</TABLE>

        4.5     Downstream Revenue Capture by the Parties. In the event ***
                succeeds in developing or commercializing Development
                Candidate(s) or Product(s) resulting from activities performed
                pursuant to this Agreement and for which the milestones
                described in Section 3.3 and Section 4.4 were paid, the parties
                will pay amounts as set forth below:

                4.5.1   CF Field and Pulmonary Fields. *** on a *** all
                        consideration received by *** from a Third Party for
                        development rights and commercialization rights to any
                        Development Candidate, CF Product for the CF Field
                        resulting from a Hit from a CF Assay or a CF-Related
                        Assay, or Product for the Pulmonary Field resulting from
                        a Hit from a CF Assay or a CF-Related Assay. Such
                        consideration will be paid on a quarterly basis
                        consistent with Section 6. Such consideration includes
                        ***; provided, however *** deduct from each quarterly
                        payment an amount equal to no more than *** of each such
                        payment for *** pass through obligations appurtenant to
                        such Development Candidate, CF Product, or Product;
                        provided, however that *** will not exceed a total of
                        *** dollars ($***). ***.

                4.5.2   Outside the CF Field and Pulmonary Field ***. ***
                        percent (***%) of all consideration received by Aurora
                        from a Third Party for development rights and
                        commercialization rights to any Development Candidate or
                        Product outside the CF Field and Pulmonary Field
                        resulting from a CF-Field and CF-Related Assay. Such
                        consideration will be paid on a quarterly basis
                        consistent with Section 6. Such consideration includes
                        ***; provided, however *** deduct from each quarterly
                        payment an amount equal to no more than *** of each such
                        payment for *** pass through obligations appurtenant to
                        such Development Candidate or Product. ***.

                4.5.3   Expense Reports. The parties will provide each other
                        sufficient information to *** received as set forth in
                        Section 4.5.1 and 4.5.2.

5       LICENSING, INTELLECTUAL PROPERTY RIGHTS AND PROPERTY

        5.1     *** License to CFF to Develop and Commercialize Products in the
                CF Field. Aurora grants to CFF a ***, worldwide, sublicensable,
                milestone and royalty bearing license under the Aurora Chemistry
                Patents and Aurora Chemistry Technology to make, use, import,
                export and sell Development Candidates and CF Products, for
                which all payments described in Sections 3 and 4, including the
                milestones described in Sections 3.3 and 4.4, have been paid,
                for the CF Field. *** commercialize Development Candidates or
                Products within *** years after the payment of the corresponding
                milestone payment for a Development Candidate, CFF's *** will
                terminate and no longer have any force or effect. Such license
                is subject to the following: 1) on a Development
                Candidate-by-Development Candidate basis such license will
                become effective when milestones are paid by CF according to
                Sections 3.3 and 4.4 and 2) ***.

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<PAGE>   12

        5.2     *** license to CFF to Develop and Commercialize Products in the
                Pulmonary Field. Aurora grants to CFF a ***, worldwide,
                sublicensable, milestone and royalty bearing license under the
                Aurora Chemistry Patents and Aurora Chemistry Technology to
                make, use, import, export and sell Development Candidates and
                Products, for which all payments described in Sections 3 and 4,
                including the milestones described in Section 3.3 and 4.4, have
                been paid, in the Pulmonary Field. *** commercialize Development
                Candidates or Products within *** years after the payment of the
                corresponding milestone payment from a Development Candidate,
                CFF's *** will terminate and no longer have any force or effect.
                Such license is subject to the following: 1) on a Development
                Candidate-by-Development Candidate basis such license will
                become effective when milestones are paid by CF according to
                Sections 3.3 and 4.4 and 2) ***.

        5.3     CFF License to Aurora in the CF Field. In the event that CFF
                Controls or owns rights to Compounds, Development Candidates and
                Products required for Aurora to fulfill its obligations under
                this Agreement, CFF grants to Aurora the right to make, use,
                import, export and sell such Compounds and Products in the CF
                Field and Pulmonary Field in accordance with this Agreement.

        5.4     Control of Prosecution. CFF will be solely responsible for
                deciding to file separate patent applications on Validated Hits
                or Leads ***, and Development Candidates and Products in the CF
                Field and all methods for treating CF developed hereunder for
                the CF Field (and corresponding expenses). Patent applications
                for Validated Hits and Leads that CFF determines to file ***
                will be filed by Aurora for CFF which patent applications and
                patents secured may be controlled by CFF pursuant to this
                Section 5.4 if they become Development Candidates; provided,
                however if CFF does not pay for milestones for such Development
                Candidates, sole control of such patents and patent applications
                will revert to Aurora and Aurora will then be responsible for
                expenses incurred after such reversion date. CFF will have sole
                responsibility and sole control, at CFF's expense, for the
                filing, prosecution (including an opposition or interference)
                and maintenance of such CF Field patents and patent applications
                upon payment of Development Candidate milestones of Sections
                3.3.4 and 4.4 for patent applications pursuing patent protection
                of such Development Candidates and Products and the
                pharmaceutical uses thereof for the CF Field; provided, however
                that CFF and any licensee or successor in interest to such
                applications covenants ***. Aurora will have sole responsibility
                and sole control, at Aurora's expense, for the filing,
                prosecution (including an opposition or interference) and
                maintenance of patents and patent applications claiming Hits,
                Leads, Development Candidates and Products and the
                pharmaceutical uses thereof and any Inventions developed
                hereunder for the Pulmonary Field *** (subject to CFF rights of
                prosecution in this Section 5.4); provided, however CFF will
                have the reasonable right to review and comment on patent
                prosecution matters in the Pulmonary Field. The Parties will
                provide each other with information developed under the
                Collaboration that is necessary for the prosecution of patent
                applications in the CF Field and Pulmonary Field pursuant to
                this Section 5.4, for enforcement rights under Section 5.5 and
                to satisfy any obligations under 37 C.F.R. ss.1.56 relating to
                the duty of disclosure.

        5.5     Control of Enforcement. CFF shall have the sole right, but not
                the obligation, to bring proceedings against any Third Party for
                the inappropriate use, including patent

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                infringement, of Technology, or Patent Rights owned or
                Controlled by it, or for which it has sole control of
                prosecution according to Section 5.6, and at its own risk and
                expense. Aurora, subject to CFF's right in the preceding
                sentence, shall have the sole right, but not the obligation, to
                bring proceedings against any Third Party for the inappropriate
                use, including patent infringement, of Technology, or Patent
                Rights owned or Controlled by it, or related to a Development
                Candidate or Product developed under this Agreement, and at its
                own risk and expense.

        5.6     Zip-lock Licenses for DNA Constructs and Assays to Certain
                Parties. Aurora will grant CFF and academic, institutional Third
                Parties designated by CFF, during the Collaborative Period if
                CFF terminates in accordance with Section 9.3 or for *** years
                from the Effective Date, with Zip-lock Licenses solely in the CF
                Field under the Aurora Patents and Aurora Technology, subject to
                CFF's obligations herein (including the payments described in
                Section 3) and the execution of appropriate *** with such Third
                Parties. Such licenses are limited to one or more of the
                following biological entities: *** developed by the parties
                under this Agreement and paid for by CFF in the CF Field;
                provided, however *** (including Development Candidates) are not
                considered ***. For clarity, CFF and such academic,
                institutional Third Parties will not be required to pay a
                license fee for such Zip-lock Licenses and Aurora will provide
                the *** to such Third Parties at Aurora's ***. Alternatively,
                Aurora may be able provide these biological entities through a
                Third Party, subject to certain license limitations similar to
                the Zip-Lock License ***.

        5.7     Option for Licenses for Aurora Chemicals to Certain Parties.
                Aurora will provide academic, institutional Third Parties
                designated by CFF with the following license:

                        "Aurora grants to such Third Party a non-exclusive
                        license under the Aurora Chemistry Patents and Aurora
                        Chemistry Technology, subject to CFF's obligations
                        pursuant to Aurora and CFF Agreement of May 2000, the
                        right to use Development Candidates ***."

                Such grant to such Third Party is subject to an express, written
                license agreement between Aurora and such Third Party that
                includes customary limitations to secure and protect
                intellectual property rights (including Patent Rights), a term
                of up to *** and renewable if necessary and obligations of
                confidentiality and assignment of all Inventions to Aurora. For
                clarity, CFF and such academic, institutional Third Parties will
                not be required to pay a license fee for such licenses, Aurora
                will provide the Development Candidates at the expense of CFF
                and such licenses are not sublicensable, or transferable.

        5.8     Use and Ownership of Data and Technology. Subject to CFF's ***
                licenses described in Sections ***, all results, data,
                Inventions, Materials, assays, Technology, Compounds,
                Development Candidates and Products generated for CFF arising
                out of this Agreement will be owned exclusively by Aurora and
                will be treated as Aurora Confidential Information, Aurora
                Technology, Aurora Chemistry Technology, Aurora Patents or
                Aurora Chemistry Patents, as the case may be and regardless of
                inventorship. Subject to CFF's *** licenses described in this
                Section ***, all such rights will be assigned to Aurora by CFF
                and its agents, and CFF or its agents will promptly perfect the
                same to Aurora and CFF will contractually obligate its agents to
                assign such rights to Aurora.

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<PAGE>   14

        5.9     Limitations. Except as otherwise expressly provided in this
                Section 5, nothing in this Agreement is intended to convey or
                transfer ownership by one party to the other of any rights,
                title or interest in any Confidential Information, Technology,
                copyrights, trademarks, trade secrets or Patent Rights owned or
                Controlled by a party. All licenses granted herein do not
                include the right to sublicense except as expressly stated in
                Section 5. Except as expressly provided for in this Agreement,
                nothing in this Agreement will be construed as a license or
                sublicense by one party to the other of any rights in any
                technology, copyrights, or patent rights owned or Controlled by
                a party. All rights not expressly granted by Aurora in this
                Section 5 are retained by Aurora. Licenses of Section 5 exclude
                any rights under the Aurora Patents, Aurora Chemistry Patents,
                Aurora Technology or Aurora Chemistry Technology outside of the
                CF Field or Pulmonary Field.

6       PAYMENTS, ACCOUNTING FOR AND RECORDS FOR DOWNSTREAM REVENUES

        6.1     Payment and Reporting. The milestones and other payments due
                under Section 4 and as follows in this Section 6, will be paid
                within *** days after the end of each calendar quarter period in
                which such payments are earned during the Royalty Term for each
                Product, as applicable. With each such quarterly payment CFF or
                Aurora will furnish the other party a financial statement,
                setting forth on a country-by-country basis: (i) list of Third
                Parties that paid consideration to Aurora or CFF, as applicable,
                in accordance with Section 4.5, (ii) total consideration
                received from each such Third Party, and (iii) itemized
                deductions for pass through obligations as described in Section
                4.5.

        6.2     Currency of Payment. All payments to be made under this
                Agreement, including the milestones and downstream revenue
                payments, paid by Aurora or CFF, as applicable, will be paid in
                U.S. dollars by wire transfer or other mutually acceptable means
                to a bank account designated in writing by the recipient.
                Payments earned in Section 4.5 shall be determined in the
                currency of the country in which they are paid and then
                converted into dollars using the rate of exchange published by
                Reuters Ltd. for the spot purchase of U.S. dollars at 7:15 a.m.,
                Eastern Standard Time, on the third (3rd) banking day following
                the receipt of such amount by the party obligated to pay under
                this Section.

        6.3     Records.

                6.3.1   Downstream Revenues Calculations. During the Term and
                        for *** years from the date of each payment of under
                        Section 4.5, CFF and Aurora, as applicable, will keep
                        complete and accurate records of sales and all other
                        information necessary to calculate payment for each
                        Product sold by Aurora or CFF as the case may be in
                        sufficient detail to allow the accrued payments to be
                        determined accurately in accordance with GAAP. One
                        party, with reasonable written notice to the other
                        party, will have the right to cause an independent,
                        certified public accountant to audit such records not
                        more than once each year at the place or places of
                        business where such records are customarily kept in
                        order to verify the accuracy of the reports of
                        downstream revenue payments but only during normal
                        business hours. The auditing party will bear the full
                        cost of such audit unless such audit discloses an
                        underpayment of more than *** percent (***) from the
                        amount of the payments due under this Agreement, in
                        which event, the audited party

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                        will bear the reasonable cost of such audit. Such
                        accountant will disclose only whether the financial
                        reports are correct and the details of any
                        discrepancies. The auditing party will cause such
                        accountant to enter into a confidentiality agreement
                        with the audited party. Within *** (***) days of
                        notification by the auditing party of any underpayment
                        of downstream revenues, the audited party will notify
                        the auditing party whether it agrees with the conclusion
                        of such accountant. If the audited party agrees with the
                        conclusion of such account, such audited party will
                        remit to the auditing the amount of any such
                        underpayment. If such accountant concludes that the
                        audited party has made an overpayment of downstream
                        revenues under Section 4.6, the auditing party will so
                        notify the audited party. If the audited party agrees
                        with the conclusion of overpayment, the amount of such
                        overpayment will be credited toward any future payments
                        payable hereunder. If there is a disagreement, the
                        parties will resolve their dispute in accordance with
                        Section 10.14.

7       TREATMENT OF CONFIDENTIAL INFORMATION; PUBLICITY

        7.1     Confidentiality.

                7.1.1   Subject to the terms and conditions of this Agreement,
                        CFF and Aurora each agree that, during the term of this
                        Agreement and for *** years thereafter, it will use best
                        efforts to keep confidential all Confidential
                        Information that is disclosed to it by the other party
                        in connection with the performance of this Agreement.
                        Neither CFF nor Aurora will use the other party's
                        Confidential Information except as expressly permitted
                        in this Agreement.

                7.1.2   CFF and Aurora each agree that any disclosure of the
                        other's Confidential Information to any officer,
                        employee, contractor, consultant, sublicensee, or agent
                        of the other party will be made only if and to the
                        extent necessary to carry out its responsibilities under
                        this Agreement and to exercise the rights granted to it
                        hereunder, will be limited to the extent consistent with
                        such responsibilities and rights, and will be provided
                        only to such persons or entities who are bound to
                        maintain same in confidence in a like manner as the
                        party receiving same hereunder is so required. CFF's
                        Confidential Information will not be disclosed, without
                        CFF's written consent, in a patent application filed by
                        Aurora. Aurora's Confidential Information will not be
                        disclosed, without Aurora's written consent not to be
                        unreasonably withheld, in a patent application filed by
                        CFF. Each party, upon the other's request, will return
                        all the Confidential Information disclosed to it by the
                        other party pursuant to this Agreement, including all
                        copies and extracts of documents, within *** days of the
                        request of the other party following any termination of
                        this Agreement, except for one (1) copy which may be
                        kept for the purpose of ascertaining and complying with
                        continuing confidentiality obligations under this
                        Agreement.

                7.1.3   Confidential Information will not include any
                        information which the receiving party can prove by
                        competent evidence:

                                i) is now, or hereafter becomes, through no
                                fault of the receiving party, generally known or
                                available;

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                                ii) is known by the receiving party at the time
                                of receiving such information, as evidenced by
                                its records;

                                iii) is hereafter furnished to the receiving
                                party without restriction as to disclosure or
                                use by a Third Party lawfully entitled to so
                                furnish same;

                                iv) is independently developed by the employees,
                                agents or contractors of the receiving party
                                without the aid, application or use of the
                                disclosing party's Confidential Information;

                                v) is the subject of a written permission to
                                disclose provided by the disclosing party; or

                                vi) is provided by the disclosing party to a
                                Third Party without restriction as to
                                confidentiality.

                A party may also disclose Confidential Information of the other
                where required to do so by law or legal process, provided that,
                in such event, the party required to so disclose will give
                maximum practical advance written notice of same to the other
                party and will cooperate with the other party's efforts to seek,
                at the request and expense of the other party, all confidential
                treatment and protection for such disclosure as is permitted by
                applicable law. The parties agree that the material financial
                terms of this Agreement will be considered Confidential
                Information of both parties. A party will have the further right
                to disclose the material financial terms of this Agreement under
                strictures of confidentiality to any potential acquirer, bona
                fide potential strategic partner or collaborator, merger
                partner, bank, venture capital firm, or other financial
                institution to obtain financing with the consent of the other
                party hereto. The parties agree that information applicable to
                drug development for CF Targets in the CF Field and Pulmonary
                Field and developed under the Collaboration will be considered
                Confidential Information of both parties and will be subject to
                the confidentiality requirements of this Section 7.1.
                Notwithstanding the foregoing, Aurora may disclose and use
                Confidential Information developed under the Collaboration for
                use with CF Targets outside the CF Field and the Pulmonary Field
                or inside the CF Field and the Pulmonary Field for non-CF
                Targets in the course of its assay development and other service
                activities under strictures of confidentiality to bona fide
                customers or licensees.

        7.2     Publication of Results. If either party desires to publish or
                otherwise disclose the results and data obtained by the parties
                in the course of the Collaboration, such party will provide a
                copy of any such proposed public disclosure to the other party
                at least *** calendar days prior to such disclosure. The other
                party will have *** calendar days from the receipt of such
                proposed public disclosure to object to the proposed disclosure
                or any portion thereof (a) on the basis that it contains or
                references unprotected patentable subject matter or (b) violates
                any provision of this Agreement, including the confidentiality
                provisions hereof or (c) is factually inaccurate.
                Notwithstanding anything herein to the contrary, if such party
                objects on the basis that the disclosure contains unprotected
                patentable subject matter, the disclosing party will refrain
                from making the disclosure for *** calendar days from the date
                of the other party's objection in order to allow the other party
                an opportunity to obtain proper legal protection for

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                the subject matter contained in the proposed public disclosure.
                In the event that the other party objects to any proposed public
                disclosure on the basis that some or all of said disclosure
                violates the confidentiality terms of this Agreement, ***. In
                addition the parties agree to credit each other when a
                publication is based in whole or in significant part of the
                other party's Technology.

        7.3     Publicity. Neither party may make any public announcement or
                otherwise disclose the terms or milestone events of this
                Agreement without the prior written consent of the other party,
                which consent will not be unreasonably withheld. Upon execution
                of this Agreement, the parties will issue a press release in the
                form mutually agreed upon or a reasonable variant thereof. Any
                additional press releases or public announcements with respect
                to this Agreement or the transactions and activities
                contemplated herein will be at such time and in such manner as
                the parties will mutually agree upon.

8       WARRANTIES, INDEMNIFICATION AND LIABILITY

        8.1     Mutual Representations and Warranties. The parties make the
                following representations and warranties to each other:

                8.1.1   Corporate Power. Each party hereby represents and
                        warrants that such party is duly organized and validly
                        existing under the laws of the state of its
                        incorporation and has full corporate power and authority
                        to enter into this Agreement and to perform its
                        obligations under the Agreement.

                8.1.2   Due Authorization. Each party hereby represents and
                        warrants that such party (a) has the requisite power and
                        authority and the legal right to enter into the
                        Agreement and to perform its obligations hereunder; and
                        (b) has taken all necessary action on its part to
                        authorize the execution and delivery of the Agreement
                        and to authorize the performance of its obligations
                        hereunder and the grant of rights extended by it
                        hereunder.

                8.1.3   Performance. Each party will exercise a standard of
                        professional practice that is consistent with the
                        practices of other entities performing like services or
                        activities.

        8.2     CFF Indemnification. CFF hereby agrees to indemnify, defend and
                hold Aurora, and its officers, directors, employees, and agents
                (collectively, the "Aurora Indemnitees") harmless from and
                against all damages or other amounts payable to a Third Party,
                including reasonable attorneys' fees and costs of litigation,
                resulting from a suit or claim brought by a Third Party against
                a Aurora Indemnitee for ***. If an Aurora Indemnitee desires
                indemnification from CFF, such Aurora Indemnitee will promptly
                and in writing notify CFF of the same pursuant to this Section
                8.2 and the circumstances surrounding such requested
                indemnification and CFF will be entitled to assume sole control
                of the defense or settlement; provided, however, that the Aurora
                Indemnitee will be entitled to participate in the defense of
                such matter and to employ counsel of its choosing and at its own
                expense to provide assistance to CFF.

        8.3     Aurora Indemnification. Aurora hereby agrees to indemnify,
                defend and hold CFF, and its officers, directors, employees, and
                agents (collectively, the "CFF Indemnitees") harmless from and
                against all damages or other amounts payable to a Third Party,
                including

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                reasonable attorneys' fees and costs of litigation, resulting
                from a suit or claim brought by a Third Party against a CFF
                Indemnitee for i) any development, manufacture, use or sale of a
                Development Candidate or Product by or through Aurora or its
                Licensees, and ii) personal injury or property damage that was
                caused by Aurora or by or to an Aurora employee or agent due to
                the willful misconduct of Aurora or such Aurora employee or
                agent in performance of this Agreement at CFF or Aurora; except
                to the extent such damages or other amounts payable are
                attributable to: (a) a violation of law and regulation or court
                order by any CFF Indemnitee, or (b) any willful misconduct of
                any CFF Indemnitee. If a CFF Indemnitee desires indemnification
                from Aurora, such CFF Indemnitee will promptly and in writing
                notify Aurora of the same pursuant to this Section 8.3 and the
                circumstances surrounding such requested indemnification and
                Aurora will be entitled to assume sole control of the defense or
                settlement; provided, however, that the CFF Indemnitee will be
                entitled to participate in the defense of such matter and to
                employ counsel of its choosing and at its own expense to provide
                assistance to Aurora.

        8.4     Limitation of Liability and Warranty. NEITHER PARTY WILL BE
                LIABLE TO THE OTHER FOR ANY SPECIAL, CONSEQUENTIAL, INCIDENTIAL,
                OR INDIRECT DAMAGES ARISING OUT OF THIS AGREEMENT, HOWEVER
                CAUSED, UNDER ANY THEORY OF LIABILITY. Except as expressly set
                forth in this Section 8, the parties MAKE NO REPRESENTATIONS AND
                EXTEND NO WARRANTIES OF ANY KIND, EITHER EXPRESS OR IMPLIED.
                THERE ARE NO EXPRESS OR IMPLIED WARRANTIES OF MERCHANTABILITY OR
                FITNESS FOR A PARTICULAR PURPOSE, OR THAT THE USE OF THE
                LICENSED PRODUCTS OR SERVICES WILL NOT INFRINGE ANY PATENT,
                COPYRIGHT, TRADEMARK, OR OTHER RIGHTS OR ANY OTHER EXPRESS OR
                IMPLIED WARRANTIES.

9       TERM AND TERMINATION

        9.1     Term. The Collaborative Period is defined as five (5) years,
                unless mutually extended by the parties or terminated earlier
                pursuant to Section 9.3. The term of this Agreement will
                commence on the Effective Date and, unless terminated earlier as
                provided in this Section 9 or extended by mutual written
                agreement of the parties, continue in full force and effect
                until the expiration of the downstream payments under this
                Agreement ("Term").

        9.2     Termination for Cause. Without limitation to pursue legal rights
                in accordance with Section 10.14, either party will have the
                right to terminate this Agreement at any time for a material
                breach of this Agreement by the other party, provided that the
                non-breaching party will have given the breaching party *** days
                (*** days in the case of non-payment) written notice of the
                breach and intention to terminate this Agreement in the absence
                of a reasonable cure by the breaching party to the reasonable
                satisfaction of the non-breaching party within such *** day
                period. Such notice will specify the alleged conditions of
                breach and contain notice of termination under this Section 9.2.
                Any disagreements between the parties regarding the existence of
                a breach, the rights and obligations of the parties hereunder or
                liability to pay damages will solely be resolved in accordance
                with Section 10.14.

        9.3     Termination without Cause of the Collaboration Period. CFF may
                terminate the

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                Collaboration Period defined in this Agreement for any reason as
                follows:

                9.3.1   *** Effective Date with advance written notice to Aurora
                        *** days before the *** the Effective Date; provided,
                        however that Aurora has *** develop at *** and complete
                        *** prior to *** of the Collaboration Period;

                9.3.2   In the event that Aurora successfully *** and *** and as
                        specified in the Work Plan prior to the *** anniversary
                        of the Effective Date as the case may be, CFF may
                        terminate the Collaboration Period by payment to Aurora
                        as follows:

                        9.3.2.1 *** dollars ($***) for termination before the
                                *** anniversary of the Effective Date;

                        9.3.2.2 *** dollars ($***) for termination before the
                                *** anniversary of the Effective Date; and

                        9.3.2.3 *** dollars ($***) for termination before the
                                *** anniversary of the Effective Date.

                9.3.3   The parties will not have any further obligations under
                        the Collaboration after such termination. If CFF
                        provides notice of intent to terminate according to
                        Section 9.3.1 prior to the *** anniversary of the
                        Effective Date, and if after the date of CFF's notice of
                        such termination Aurora completes such obligations
                        specified in Section 9.3.1 then CFF may withdraw its
                        intent to terminate, or terminate in accordance with
                        Section 9.3.2 within *** days of Aurora's notice to CFF
                        that such obligations have been fulfilled.

        9.4     Effect of Expiration or Termination. Expiration or termination
                of this Agreement will not relieve the parties of any obligation
                accruing prior to such expiration or termination. The
                obligations and rights of the parties under Sections 4, 6, 7, 9
                and 10 will survive termination or expiration of this Agreement.
                Except as otherwise expressly provided in this Agreement, the
                rights and obligations of the parties under Section 5 hereof
                will terminate and be of no further force or effect whatsoever
                upon any termination of this Agreement. After any termination of
                Zip-Lock Licenses all transferred Materials under Zip-Lock
                Licenses will be destroyed or transferred back to Aurora within
                *** days.

10      MISCELLANEOUS

        10.1    Assignment. Notwithstanding any provision of this Agreement to
                the contrary, neither party may assign any of its rights or
                obligations under this Agreement in any country to any Third
                Party without the written consent of the non-assigning party
                except that CFF may assign this Agreement to an entity that is
                controlled by or under common control with CFF; provided,
                however, that any such assignment will not relieve the assigning
                party of its responsibilities for performance of its obligations
                under this Agreement. Either party may also assign its rights
                and obligations under this Agreement in connection with the sale
                of all or substantially all of its assets, or may otherwise
                assign its

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                rights or obligations under this Agreement with the prior
                written consent of the other party. This Agreement will survive
                any merger or consolidation of either party with or into another
                party and no consent for any such merger, consolidation or
                similar reorganization will be required hereunder.

        10.2    Binding Effect. This Agreement will be binding upon and inure to
                the benefit of the successors and permitted assigns of the
                parties. Any assignment not in accordance with this Agreement
                will be void.

        10.3    Force Majeure. Neither party will lose any rights hereunder or
                be liable to the other party for damages or losses on account of
                failure of performance by the defaulting party if the failure is
                occasioned by war, fire, explosion, flood (including but not
                limited to, floods caused by El Nino), earthquake, strike,
                lockout, embargo, act of God, or any other similar cause beyond
                the control of the defaulting party, provided that the party
                claiming force majeure has exerted all reasonable efforts to
                avoid or remedy such force majeure and thereafter takes all
                reasonable steps to mitigate any such delay in performance
                hereunder and any damages that may be incurred by the other
                party thereby.

        10.4    Notices. Any notices or communications provided for in this
                Agreement to be made by either of the parties to the other will
                be in writing, in English, and will be made by prepaid air mail
                with return receipt addressed to the other at its address set
                forth below. Any such notice or communication may also be given
                by hand, by courier or by facsimile to the appropriate
                designation. Notices will be sent:

                            If to CFF, to:        Cystic Fibrosis Foundation
                                                  6931 Arlington Road, 2nd Floor
                                                  Bethesda, Maryland 20814

                            Attention:            Robert J. Beall, PH.D.
                                                  President

                            Copy:                 Kenneth Schaner
                                                  3000 K Street NW
                                                  Washington, D.C. 20007
                                                  and
                                                  Melissa Ashlock, M.D.
                                                  6931 Arlington Road, 2nd Floor
                                                  Bethesda, Maryland 20814

                            If to Aurora, to:     Aurora Biosciences Corporation
                                                  11010 Torreyana Road
                                                  San Diego, CA 92121

                            Attention:            Michael J. Dunn
                                                  Vice President,
                                                  Business Development

                            Copy:                 John Mendlein
                                                  General Counsel,
                                                  Chief Knowledge Officer

        Either party may by like notice specify or change an address to which
        notices and communications will thereafter be sent. Notices sent by
        mail, facsimile or courier will be effective upon receipt and notices
        given by hand will be effective when delivered.

        10.5    Governing Law and Jurisdiction. This Agreement will be governed
                by the laws of the State of California, without regard to its
                rules of conflict of laws as such laws are applied to contracts
                entered into and to be performed within such state.

        10.6    Waiver. Except as specifically provided for herein, the waiver
                from time to time by either of the parties of any of their
                rights or their failure to exercise any remedy will not operate
                or be construed as a continuing waiver of same or any other of
                such party's rights or remedies provided in this Agreement.

        10.7    Severability. If any term, covenant or condition of this
                Agreement or the application thereof to any party or
                circumstance will, to any extent, be held to be invalid or
                unenforceable, then the remainder of this Agreement, or the
                application of such term, covenant or condition to parties or
                circumstances other than those as to which it is held invalid or
                unenforceable, will not be affected thereby and each term,
                covenant or condition of this Agreement will be valid and be
                enforced to the fullest extent permitted by law; and

                                     20/50
<PAGE>   21

                the parties hereto covenant and agree to renegotiate any such
                term, covenant or application thereof in good faith in order to
                provide a reasonably acceptable alternative to the term,
                covenant or condition of this Agreement or the application
                thereof that is invalid or unenforceable, it being the intent of
                the parties that the basic purposes of this Agreement are to
                effectuated.

        10.8    Independent Contractors. It is expressly agreed that Aurora and
                CFF will be independent contractors and that the relationship
                between the two parties will not constitute a partnership or
                agency of any kind. Neither Aurora nor CFF will have the
                authority to make any statements, representations or commitments
                of any kind, or to take any action, which will be binding on the
                other, without the prior written authorization of the party to
                do so.

        10.9    Counterparts. This Agreement may be executed in two or more
                counterparts, each of which will be deemed an original, but all
                of which together will constitute one and the same instrument.

        10.10   Entire Agreement. This Agreement between the parties (including
                all Exhibits) sets forth all of the covenants promises,
                agreements, warranties, representations, conditions and
                understandings between the parties hereto, and supersedes and
                terminates all prior agreements and understanding between the
                parties, with respect to the subject matter hereof. There are no
                covenants, promises, agreements, warranties, representation
                conditions or understandings; either oral or written, between
                the parties other than as set forth herein and therein. No
                subsequent alteration, amendment, change or addition to this
                Agreement will be binding upon the parties hereto unless reduced
                to writing and signed by the respective authorized officers of
                the parties. This Agreement will not be strictly construed
                against either party hereto. Any conflict between the terms set
                forth in the text of this Agreement and the terms of any Exhibit
                hereto will be resolved in favor of the text of this Agreement.
                The written agreement between the parties of September 9, 1999
                will be terminated as of the Effective Date of this Agreement
                and such prior agreement will no longer have any force or
                effect.

        10.11   No Third Party Beneficiaries. No Third Party, including any
                employee of any party to this Agreement when acting within the
                scope of his or her employment, will have or acquire any rights
                by reason of this Agreement. Nothing contained in this Agreement
                will be deemed to constitute the parties partners with each
                other or any third party.

        10.12   Advice of Counsel. This Agreement has been negotiated by the
                parties and their respective counsel and will be fairly
                interpreted in accordance with its terms and without application
                of any rules of construction relating to which party drafted the
                Agreement being applied in favor or against either party.

        10.13   Construction. The term "Section" can refer to any single
                paragraph level found therein or any collection of multiple
                paragraphs within such Section.

        10.14   Dispute Resolution. The parties recognize that disputes as to
                certain matters may from time to time arise during the term of
                this Agreement which relate to either party's rights and/or
                obligations hereunder. It is the objective of the parties to
                establish procedures

                                     21/50
<PAGE>   22

                to facilitate the resolution of disputes arising under this
                Agreement in an expedient manner by mutual cooperation and
                without resorting to arbitration. The parties agree that prior
                to any arbitration concerning this Agreement, a member of CFF's
                senior management and Aurora's president will meet in person or
                by video-conferencing in a good faith effort to resolve any
                disputes concerning this Agreement. Within *** of a formal
                request by either party to the other, any party may, by written
                notice to the other, have such dispute referred to their
                respective officers designated or their successors, for
                attempted resolution by good faith negotiations, such good faith
                negotiations to begin within *** after such notice is received.
                Any dispute arising out of or relating to this Agreement which
                is not resolved between the parties or the designated officers
                of the parties pursuant to Section 10.14 will be resolved by
                final and binding arbitration conducted in *** under the then
                current Licensing Agreement Arbitration Rules of the American
                Arbitration Association ("AAA"). The arbitration will be
                conducted by three (3) arbitrators who are knowledgeable in the
                subject matter which is at issue in the dispute. One arbitrator
                will be selected by CFF and one arbitrator will be selected by
                Aurora and the third arbitrator will be appointed by the AAA. In
                conducting the arbitration, the arbitrator will determine what
                discovery will be permitted, consistent with the goal of
                limiting the cost and time which the parties must expend for
                discovery (and provided that the arbitrators will permit such
                discovery they deem necessary to permit an equitable resolution
                of the dispute), and will be able to decree any and all relief
                of an equitable nature, including but not limited to such relief
                as a temporary restraining order, a preliminary injunction, a
                permanent injunction, specific performance or replevin of
                property. The arbitrators will also be able to award actual or
                general damages, but will not award any other form of damage
                (e.g., consequential, punitive or exemplary damages). During the
                course of the arbitration neither party may terminate the
                Agreement for the cause giving rise to such arbitration, halt
                payments, curtail research or otherwise fail to perform its
                obligations under this Agreement. The parties will share equally
                the arbitrator's fees and expenses pending the resolution of the
                arbitration unless the arbitrators require the non-prevailing
                party to bear all or any portion of the costs of the prevailing
                party. The decision of the arbitrators will be final and may be
                sued on or enforced by the party in whose favor it runs in any
                court of competent jurisdiction at the option of such party.
                Notwithstanding anything to the contrary in this Section 10,
                either party may seek immediate injunctive or other interim
                relief from any court of competent jurisdiction with respect to
                any breach of Sections 6, or 7 hereof, or otherwise to enforce
                and protect the patent rights, copyrights, trademarks, or other
                intellectual property rights owned or Controlled by such party.
                In no event will a demand for arbitration be made after the date
                when the institution of a legal or equitable proceeding based on
                such claim, dispute or other matter in question would be barred
                by the applicable statute of limitations.

                                     22/50
<PAGE>   23

IN WITNESS WHEREOF, the parties have caused this Agreement to be executed by
their duly authorized representatives.

CYSTIC FIBROSIS FOUNDATION             AURORA BIOSCIENCES CORPORATION

By:                                By:

Name:    Robert J. Beall, Ph.D.    Name:     Stuart J.M. Collinson, Ph.D.

Title:   President                 Title:    President & Chief Executive Officer

Date:                              Date:

                                     23/50
<PAGE>   24

                                    EXHIBIT 1
                                   DEFINITIONS

As used in this Agreement, the following terms will have the following meanings:

        "Agreement" means this agreement, together with all appendices, exhibits
        and schedules hereto, and as the same may be amended or supplemented
        from time to time hereafter by a written agreement duly executed by
        authorized representatives of each party hereto.

        "Aurora Chemicals" means compounds owned or Controlled by Aurora *** for
        by CFF as set forth in Section 3.3.4, which may be amended by mutual
        written consent.

        "Aurora Chemistry Patents" means 1) Patent Rights owned or Controlled by
        Aurora as set forth in Exhibit 5.1 for Aurora Chemicals and 2) Patent
        Rights for Aurora Chemicals owned or Controlled by Aurora and developed
        solely under this Agreement; both of which are set forth in Exhibit 5.1
        and may be amended by mutual written consent.

        "Aurora Chemistry Technology" means 1) Technology owned or Controlled by
        Aurora for Aurora Chemicals and 2) Technology for Aurora Chemicals owned
        or Controlled by Aurora developed solely under this Agreement; both of
        which are set forth in Exhibit 5.1 and may be amended by mutual written
        consent.

        "Aurora Patents" means Patent Rights owned or Controlled by Aurora as
        set forth in Exhibit 5.6A, and Patent Rights owned or Controlled by
        Aurora developed solely under this Agreement and may be amended by
        mutual written consent.

        "Aurora Technology" means Technology owned or Controlled by Aurora as of
        the Effective Date as set forth in Exhibit 2.3.8, and Technology owned
        or Controlled by Aurora developed solely under this Agreement and may be
        amended by mutual written consent.

        "***" means the percentage increase or decrease in the average of the
        following and not to exceed *** on an annual basis: 1) CPI (Consumer
        Price Index) for the year preceding such adjustment and 2) salaries for
        research scientists *** for the year preceding such adjustment and using
        the year 2000 as the base year.

        "CF" means Cystic Fibrosis, a genetic disorder of the CFTR gene that
        results in improperly regulated fluid secretion in the lungs and other
        exocrine tissues and its sequellae in patients with such genetic
        disorder.

        "CF Assay" means ***.

        "CF-Related Assay" means a ***.

        "CF Field" means for the discovery, development and treatment of CF ***.

                                     24/50
<PAGE>   25

        "CF Product" means a Product licensed from Aurora to CFF under this
        Agreement in the CF Field under Section 5.1.

        "CF Target" means a ***.

        "Chemistry Advisory Group" means an independent Third Party mutually
        agreed upon in writing by CFF and Aurora to advise CFF regarding assay
        development, milestone achievement, in vivo testing, Validated Hits,
        Lead prioritization and optimization, and Development Candidate
        selection and development; provided, however such Third Party is
        obligated in writing to CFF and Aurora to a confidentiality and
        proprietary inventions agreement and covenants to use any Aurora
        Confidential information solely for the Collaboration.

        "Collaboration" means the research alliance between the CFF and Aurora
        directed to the discovery of novel therapeutics for CF during the
        Collaborative Period.

        "Collaboration Assets" is defined in Section 3.2.3.

        "Collaboration Committee" means a committee comprised of up to ***
        representatives appointed by CFF (any Third Party representatives are
        required to be under a confidential disclosure and proprietary
        inventions agreement with Aurora), and up to *** representatives
        appointed by Aurora; *** of whom from each party will be voting members.

        "Collaboration Manager" means the lead contact person to the Steering
        Committee designated by Aurora and subject to the approval of the
        Steering Committee.

        "Collaborative Period" means the period of time that begins on the
        Effective Date and continues until the day preceding the *** anniversary
        of the Effective Date, unless extended by mutual written agreement of
        the Parties, or terminated earlier in accordance with Section 9.

        "Compound" means any molecule provided by Aurora or CFF in accordance
        with this Agreement ***.

        "Confidential Information" means all information, data, and Materials
        received by either party from the other party pursuant to this Agreement
        and all information, data, and Materials developed in the course of the
        collaboration and/or activities of the parties under this Agreement,
        including, without limitation, Technology of each party, subject to the
        exceptions set forth in Section 7.1.3.

        "Control" or "Controlled" means, with respect to tangible and
        intellectual property, possession by a party of the ability to grant a
        license or sublicense in accordance with the terms of this Agreement,
        and without violating the terms of any agreement by such party with any
        Third Party.

        "Derivative" means a ***.

                                     25/50
<PAGE>   26

        "Development Candidate" means any Lead or Derivative that is *** by the
        Steering Committee after recommendation by the Collaboration Committee
        for clinical development under this Agreement and that demonstrates
        substantially the following:

                1. ***;

                2. ***;

                3. ***;

                4. ***; and

                5. ***.

        In the event that a Lead or Derivative reaches an IND submission without
        designation as a Development Candidate, such Lead or Derivative will be
        deemed a Development Candidate for purposes of this Agreement.

        "Effective Date" means May 19, 2000.

        "FDA" will mean the United States Food and Drug Administration, or any
        successor agency having regulatory jurisdiction over the manufacture,
        distribution and sale of drugs in the United States or equivalent
        governmental agency or authority in any other jurisdiction.

        "FTE" or "Full Time Equivalent" will mean the full time equivalent of
        one (1) Aurora or contracted researcher, based on a minimum effort of
        *** hours per year, and charged at a rate of *** dollars ($***) per
        year; as adjusted by the ***.

        "Hit" means any Compound that demonstrates activity in a CF-Related
        Assay or CF Assay developed under the Collaboration *** and demonstrates
        substantially the following:

                1. ***.

                2. ***.

                3. ***.

                4. ***.

        "IND" means an Investigational New Drug application filed with and
        accepted by the FDA or any corresponding application filed in any
        country other than the United States or the first administration of a
        Development Candidate into a human subject.

        "Invention" means any new and useful idea or discovery, including
        without limitation a new and useful process, machine, manufacture, or
        composition of matter, or improvement thereto, whether or not
        patentable.

        "Know-How" means information and data that is not generally known to the
        public, including, but not limited to: Inventions, designs, concepts,
        algorithms, formulae, software, techniques, practices, processes,
        methods, knowledge, skill, experience, expertise and technical
        information.

        "Lead" means a ***:

                                       ***

                                     26/50
<PAGE>   27

        "Materials" means any ***.

        "Milestone Arbitrator" means an independent Third Party mutually agreed
        upon in writing by CFF and Aurora *** and such Third Party will have a
        confidential and proprietary inventions agreement with Aurora.

        "NDA" means a New Drug Application or the equivalent, and all
        supplements pursuant to the requirements of the FDA, including all
        documents, data and other information concerning Products which are
        necessary for FDA approval to market a Product, or the equivalent
        governmental approval in any other country.

        "Patent Rights" means all U.S. or foreign (including regional
        authorities such as the European Patent Office) regular or provisional
        patent applications, including any continuation, continuation-in-part,
        or division thereof or any substitute application therefor or equivalent
        thereof, and any patent issuing thereon, including any reissue,
        reexamination or extension thereof and any confirmation patent or
        registration patent or patent of additions based on any such patent,
        containing one or more claims to an Invention (and in the case of an
        issued patent, containing one or more Valid Claims), and which a party
        hereto owns or Controls, individually or jointly, any title thereto or
        rights thereunder.

        "Pulmonary Field" means discovery, development and treatment of disease
        in human pulmonary tract or lungs ***.

        "Product" means any pharmaceutical product that incorporates a
        Development Candidate paid for by CFF as an ingredient.

        "Steering Committee" means a committee comprised of *** members
        appointed by CFF and *** members appointed by Aurora, (of which *** from
        each group will also be members of the Collaboration Committee).

        "Technology" means Materials and Know-How.

        "Term" means the time period defined in Section 9.1.

        "Third Party" means any entity other than Aurora and CFF.

        "Valid Claim" means: ***.

        "Validated Hit" means a Hit that substantially demonstrates:

                1. ***;

                2. ***;

                3. ***; and

                4. ***.

        "Work Plan" means the mutually agreed upon written plan attached as
        Exhibit 2, as amended in writing from time to time by the parties hereto
        through the Collaboration Committee and

                                     27/50
<PAGE>   28

        approved by the Steering Committee, outlining drug discovery projects
        and research within the Collaboration during the Collaborative Period;
        provided, however that Work Plan may be amended through the
        Collaboration Committee without execution of an Amendment by the parties
        when such amendments are within the scope of the prior Work Plan.

        "Zip-lock License" means the license in Exhibit 5.6B.

                                     28/50
<PAGE>   29

                                   EXHIBIT 2.1

                                       ***

                                  EXHIBIT 2.3.8
                                AURORA TECHNOLOGY

                                       ***

                                  EXHIBIT 3.2.2

                                       ***

                                   EXHIBIT 5.1

                                       ***

                                  EXHIBIT 5.6 A

                                       ***

                                  EXHIBIT 5.6B
                                ZIP-LOCK LICENSE

                                       ***

                                     29/50<PAGE>   1
                                                                   EXHIBIT 10.17

                           CHANGE OF CONTROL AGREEMENT

        This Change of Control Agreement (the "Agreement") is made and entered
into as of July 14, 2000 (the "Effective Date"), by and between McAfee.com, a
Delaware corporation (the "Company") and Srivats Sampath ("Executive").

                                    RECITALS

        The Company recognizes that the possibility of a change of control or
other event may occur which may change the nature and structure of the Company
and that uncertainty regarding the consequences of such events may adversely
affect the Company's ability to retain its key employees. The Company also
recognizes that the Executive possesses an intimate and essential knowledge of
the Company upon which the Company may need to draw for objective advice and
continued services in connection with any acquisition of the Company or other
change of control that is potentially advantageous to the Company's
stockholders. The Company believes that the existence of this Agreement will
serve as an incentive to Executive to remain in the employ of the Company and
will enhance its ability to call on and rely upon the Executive in connection
with a change of control.

        The Company and the Executive desire to enter into this Agreement in
order to provide additional compensation and benefits to the Executive and to
encourage Executive to continue to devote his full attention and dedication to
the Company and to continue his Change of Control with the Company.

        1. Definitions. As used in this Agreement, unless the context requires a
different meaning, the following terms shall have the meanings set forth herein:

               (a)    "Business Combination" means:

                          (i) any "person" (as such term is used in Sections
13(d) and 14(d) of the Securities Exchange Act of 1934, as amended (the
"Exchange Act")), other than a trustee or other fiduciary holding securities of
the Company under an employee benefit plan of the Company or Network Associates,
becomes the "beneficial owner" (as defined in Rule 13d-3 promulgated under the
Exchange Act), directly or indirectly, of securities of the Company representing
fifty percent (50%) or more of (A) the outstanding shares of common stock of the
Company or (B) the combined voting power of the Company's then-outstanding
securities;

                          (ii) the Company is party to a merger or consolidation
which results in the holders of voting securities of the Company outstanding
immediately prior thereto failing to continue to represent (either by remaining
outstanding or by being converted into voting securities of the surviving
entity) at least fifty percent (50%) of the combined voting power of the voting
securities of the Company or such surviving entity outstanding immediately after
such merger or consolidation;

<PAGE>   2

                          (iii) the sale or disposition of all or substantially
all of the Company's assets (or any transaction having similar effect is
consummated); or

               (b) "Cause" means:

                          (i) theft, a material act of dishonesty, fraud, the
intentional falsification of any Change of Control or Company records or the
commission of any criminal act which impairs Executive's ability to perform his
duties under this Agreement;

                          (ii) breach of the name of Employee Inventions and
Proprietary Rights Assignment Agreement signed by Employee; or

                          (iii) continued violations by the Employee of the
Employee's obligations which are demonstrably willful and deliberate on the
Employee's part after there has been delivered to the Employee a written demand
for performance from the Company which describes the basis for the Company's
belief that the Employee has not substantially performed his duties.

               (c) "Change of Control" means:

                          (i) a change in the composition of the Board of
Directors of the Company occurring within a two-year period, as a result of
which fewer than a majority of the directors are Incumbent Directors. "Incumbent
Directors" shall mean directors who either (A) are directors of the Company as
of the date hereof, or (B) are elected, or nominated for election, to the Board
of Directors of the Company with the affirmative votes of at least a majority of
the Incumbent Directors at the time of such election or nomination (but shall
not include an individual not otherwise an Incumbent Director whose election or
nomination is in connection with an actual or threatened proxy contest relating
to the election of directors to the Company);

                          (ii) the dissolution or liquidation of the Company; or

                          (iii) a Business Combination of NETA (applying the
definition of Section 1(a) above but with regard to NETA (i.e., substituting
"NETA" for the "Company") while NETA owns at least 50.1% of the voting power of
the Company.

               (d) "Good Reason" means the occurrence of any of the following
conditions, without Executive's written consent, which condition(s) remain(s) in
effect twenty (20) days after written notice to the Board from Executive of such
condition(s):

                          (i) a five percent (5%) decrease in Executive's base
salary and/or a material decrease in Executive's bonus compensation or employee
benefits following a Change of Control;

                          (ii) a demotion, a material reduction in Executive's
position, responsibilities or duties, or a material, adverse change in
Executive's substantive functional responsibilities or duties, as measured
against Executive's position, responsibilities or duties immediately prior to
such change causing it to be of materially less stature or responsibility;

                                      -2-
<PAGE>   3

                          (iii) in the event of the relocation of Executive's
work place for the Company to a location more than fifty (50) miles from the
Executive's principal place employment Control immediately prior to the Change
of Control;

                          (iv) any material breach of this Agreement by the
Company; or

                          (v) any failure or refusal of a successor company to
assume the Company's obligations under this Agreement as required by Section 14.

               (e) "Permanent Disability" means that:

                          (i) the Executive has been incapacitated by bodily
injury or disease so as to be prevented thereby from performing the essential
functions of the Executive's job with or without reasonable accommodation;

                          (ii) such total incapacity shall have continued for a
period of six consecutive months; and

                          (iii) such incapacity will, in the opinion of a
qualified physician, be permanent and continuous during the remainder of the
Executive's life.

               (f) "Termination Upon a Change of Control" means any termination
(i) of the Executive by the Company without Cause (A) within twelve (12) months
after the date of the closing of the Change of Control; or (B) after the signing
but before the closing of the Change of Control or (ii) by Executive for Good
Reason within 12 months after a Change of Control.

        "Termination Upon Change of Control" shall not include any termination
of employment of the Executive (a) by the Company for Cause; (b) by the Company
as a result of the Permanent Disability of the Executive; (c) as a result of the
death of the Executive; or (d) as a result of the voluntary termination of
employment by the Executive for reasons other than Good Reason within twelve
(12) months after the occurrence of any Change of Control.

               (g) "Total Annual Earnings" means the sum of the Executive's
annual salary excluding any bonus payments.

        2. Position and Duties. Executive shall continue to be an at-will
Executive of the Company employed in his current position at his then current
salary rate. Executive shall also be entitled to continue to participate in and
to receive benefits on the same basis as other executive or senior staff members
under any of the Company's employee benefit plans as in effect from time to
time. In addition, Executive shall be entitled to the benefits afforded to other
employees similarly situated under the Company's vacation, holiday and business
expense reimbursement policies. Executive agrees to devote his full business
time, energy and skill to his duties at the Company. These duties shall include,
but not be limited to, any duties consistent with his position which may be
assigned to Executive from time to time.

                                      -3-
<PAGE>   4

        3. No Benefits Prior to a Change of Control. Except as provided
specifically herein, prior to a Change of Control, Executive's termination of
employment with the Company for any reason, including an involuntary termination
by the Company without Cause or Executive's voluntary termination of employment
with the Company for Good Reason, shall not entitle Executive to any
compensation or benefits from the Company other than those earned under Section
2 above through the date of Executive's termination of employment.

        4. Option and Restricted Stock Acceleration Prior to a Change of
Control. In the event that an acquiring company or any successor company does
not assume or substitute equivalent options for all outstanding stock options
granted by the Company to the Executive prior to the Change of Control, then (i)
such stock options shall become fully vested and exercisable immediately prior
to the Change of Control and the Company shall give Executive at least ten days
prior notice of such acceleration of vesting and (ii) any restricted stock of
the Company owned by Executive shall become fully vested and the Company's right
of repurchase shall lapse in full.

        5. Termination Upon a Change of Control. In the event of the Executive's
Termination Upon a Change of Control and Executive signing a Release of Claims
pursuant to Section 14 of this Agreement, Executive shall be entitled to the
following separation benefits:

                          (i) all salary, accrued but unused vacation earned
through the date of Executive's termination and Executive's target bonus for the
year in which termination occurs, pro rated through the date of Executive's
termination;

                          (ii) twelve (12) months of Executive's Total Annual
Earnings as in effect as of the date of such termination, less applicable
withholding, paid in a lump sum within thirty (30) days after the date of
Executive's termination upon a Change of Control;

                          (iii) all stock options granted by the Company to the
Executive prior to the Change of Control shall become fully vested and
exercisable as of the date of the termination to the extent such stock options
remain outstanding and unexercised at the time of such Termination Upon Change
of Control;

                          (iv) all restricted stock of the Company owned by
Executive shall be fully vested and any repurchase rights shall lapse;

                          (v) within reasonable time following submission of
proper expense reports by the Executive, the Company shall reimburse the
Executive for all expenses reasonably and necessarily incurred by the Executive
in connection with the business of the Company prior to his termination of
Change of Control;

                          (vi) reimbursement to the Executive for the same level
of health coverage and benefits as in effect for the Executive on the day
immediately preceding the day of the Executive's termination of employment with
the Company; provided, however, that (i) the Executive constitutes a qualified
beneficiary, as defined in Section 4980B(g)(1) of the Internal Revenue Code of
1986, as amended; and (ii) Executive elects continuation coverage pursuant to
the Consolidated Omnibus Budget Reconciliation Act of 1985, as amended
("COBRA"), within the time period

                                      -4-
<PAGE>   5

prescribed pursuant to COBRA. The Company shall continue to reimburse Executive
for continuation coverage until the earlier of (i) the date Executive is no
longer eligible to receive continuation coverage pursuant to COBRA, or (ii) one
year from the termination date. Executive shall be responsible for the payment
of COBRA premiums (including, without limitation, all administrative expenses)
for the remaining COBRA period

                          (vii) Executive shall receive the benefits, if any,
under the Company's 401(k) Plan and other Company benefit plans to which he may
be entitled pursuant to the terms of such plans.

        6. Payment of Taxes. All payments made to Executive under this Agreement
shall be subject to all applicable federal state local and foreign (if
applicable) income, employment and payroll taxes.

        7. Exclusive Remedy. Under any claim for breach of this Agreement or
wrongful termination, the payments and benefits provided for in Section 5 shall
constitute the Executive's sole and exclusive remedy for any alleged injury or
other damages arising out of the cessation of the employment relationship
between the Executive and the Company in the event of Executive's termination.
Except as expressly set forth herein, the Executive shall be entitled to no
other compensation, benefits, or other payments from the Company as a result of
any termination of employment with respect to which the payments and/or benefits
described in Section 4 have been provided to the Executive.

        8. Proprietary and Confidential Information. The Executive agrees to
continue to abide by the terms and conditions of the Company's Employee
Proprietary Rights and Invention Assignment Agreement between the Executive and
the Company.

        9. Arbitration. Any claim, dispute or controversy arising out of this
Agreement, the interpretation, validity or enforceability of this Agreement or
the alleged breach thereof shall be submitted by the parties to binding
arbitration in Santa Clara County, California or elsewhere by mutual agreement.
The selection of the arbitrator and procedure shall be governed by the National
Rules for the Resolution of Change of Control Disputes of the American
Arbitration Association. The arbitrator shall be someone with an Change of
Control law background and from the AAA Commercial Arbitration Panel, or if both
parties agree, the Judicial Arbiters Group. Notwithstanding the above, this
arbitration provision shall not preclude either party from seeking injunctive
relief from any court having jurisdiction with respect to any disputes or claims
including any disputes or claims relating to or arising out of the misuse or
misappropriation of the Company's trade secrets or confidential and proprietary
information or the breach of any provisions by Executive of the Company's
confidentiality and/or proprietary rights agreement between the Executive and
Company. All costs and expenses of arbitration or litigation, including but not
limited to attorneys fees and other costs reasonably incurred by the Executive,
shall be paid by the Company. Judgment may be entered on the award of the
arbitration in any court having jurisdiction.

        10. Limitation of Payments and Benefits.

                                      -5-
<PAGE>   6

               (a) In the event that the severance and other benefits provided
for in this Agreement or otherwise payable to the Employee (i) constitute
"parachute payments" within the meaning of Section 280G of the Internal Revenue
Code of 1986, as amended (the "Code") and (ii) but for this Section 5, would be
subject to the excise tax imposed by Section 4999 of the Code, then the
Employee's severance benefits under Section 3(a)(1) shall be either

                      (A)    delivered in full, or

                      (B)    delivered as to such lesser extent which would
                             result in no portion of such severance benefits
                             being subject to excise tax under Section 4999 of
                             the Code,

whichever of the foregoing amounts, taking into account the applicable federal,
state and local income taxes and the excise tax imposed by Section 4999, results
in the receipt by the Employee on an after-tax basis, of the greatest amount of
severance benefits, notwithstanding that all or some portion of such severance
benefits may be taxable under Section 4999 of the Code. Any taxes due under
Section 4999 shall be the responsibility of the employee.

               (b) If a reduction in the payments and benefits that would
otherwise be paid or provided to the Employee under the terms of this Agreement
is necessary to comply with the provisions of Section 5(a), the Employee shall
be entitled to select which payments or benefits will be reduced and the manner
and method of any such reduction of such payments or benefits (including but not
limited to the number of options that would vest under Section 3(a)) subject to
reasonable limitations (including, for example, express provisions under the
Company's benefit plans) (so long as the requirements of Section 5(a) are met).
Within thirty (30) days after the amount of any required reduction in payments
and benefits is finally determined in accordance with the provisions of Section
5(c), the Employee shall notify the Company in writing regarding which payments
or benefits are to be reduced. If no notification is given by the Employee, the
Company will determine which amounts to reduce. If, as a result of any reduction
required by Section 5(a), amounts previously paid to the Employee exceed the
amount to which the Employee is entitled, the Employee will promptly return the
excess amount to the Company.

               (c) Unless the Company and the Employee otherwise agree in
writing, any determination required under this Section 5 shall be made in
writing by the Company's Accountants immediately prior to Change of Control,
whose determination shall be conclusive and binding upon the Employee and the
Company for all purposes. For purposes of making the calculations required by
this Section 5, the Accountants may, after taking into account the information
provided by the Employee, make reasonable assumptions and approximations
concerning applicable taxes and may rely on reasonable, good faith
interpretations concerning the application of Sections 280G and 4999 of the
Code. The Company and the Employee shall furnish to the Accountants such
information and documents as the Accountants may reasonably request in order to
make a determination under this Section. The Company shall bear all costs the
Accountants may reasonably incur in connection with any calculations
contemplated by this Section 5.

                                      -6-
<PAGE>   7

        11. Interpretation. Executive and the Company agree that this Agreement
shall be interpreted in accordance with and governed by the internal substantive
laws of the State of California, without regard to such state's conflict of laws
rules.

        12. Conflict in Benefits. This Agreement shall supersede all prior
arrangements, whether written or oral, and understandings regarding the subject
matter of this Agreement and shall be the exclusive agreement for the
determination of any payments and accelerated option vesting due upon
Executive's termination of employment or a Change of Control; provided, however,
that this Agreement is not intended to and shall not affect, limit or terminate
(i) any plans, programs, or arrangements of the Company that are regularly made
available to similarly-situated employees of the Company, (ii) any agreement or
arrangement with the Executive that has been reduced to writing and which does
not relate to the subject matter hereof, (iii) any indemnification rights
described below, or (iv) any agreements or arrangements hereafter entered into
by the parties in writing, except as otherwise expressly provided herein.

        13. Release of Claims. No benefits shall be paid to Executive under this
Agreement unless and until the Executive shall, in consideration of the payment
of such benefit, execute a release of claims in a form satisfactory to the
Company; provided, however, that such release shall not apply to any prior right
of Executive to be indemnified by the Company.

        14. Successors and Assigns.

               (a) Successors of the Company. The Company will require any
successor or assign (whether direct or indirect, by purchase, merger,
consolidation or otherwise) to all or substantially all of the business and/or
assets of the Company, expressly, absolutely and unconditionally to assume and
agree to perform this Agreement in the same manner and to the same extent that
the Company would be required to perform it if no such succession or assignment
had taken place. Failure of the Company to obtain such agreement prior to the
effectiveness of any such succession transaction shall be a breach of this
Agreement and shall entitle the Executive to terminate his Change of Control
with the Company within three months thereafter and to receive the benefits
provided under Section 5 of this Agreement in the event of Termination Upon a
Change of Control. As used in this Agreement, "Company" shall mean the Company
as defined above and any successor or assign to its business and/or assets as
aforesaid which executes and delivers the agreement provided for in this Section
15 or which otherwise becomes bound by all the terms and provisions of this
Agreement by operation of law.

               (b) Heirs of Executive. This Agreement shall inure to the benefit
of and be enforceable by the Executive's personal and legal representatives,
executors, administrators, successors, heirs, distributees, devises and
legatees.

        15. Notices. For purposes of this Agreement, notices and all other
communications provided for in the Agreement shall be in writing and shall be
deemed to have been duly given when delivered or mailed by United States
registered mail, return receipt requested, postage prepaid, as follows:

                                      -7-
<PAGE>   8

                      If to the Company:            McAfee.com
                                                    3965 Freedom Circle
                                                    Santa Clara, CA  95054
                                                    Attn: General Counsel

and if to the Executive at the address specified at the end of this Agreement.
Notice may also be given at such other address as either party may have
furnished to the other in writing in accordance herewith, except that notices of
change of address shall be effective only upon receipt.

        16. No Representations. Executive acknowledges that he/she is not
relying and has not relied on any promise, representation or statement made by
or on behalf of the Company which is not set forth in this Agreement.

        17. Validity. If any one or more of the provisions (or any part thereof)
of this Agreement shall be held invalid, illegal or unenforceable in any
respect, the validity, legality and enforceability of the remaining provisions
(or any part thereof) shall not in any way be affected or impaired thereby.

        18. Modification. This Agreement may only be modified or amended by a
supplemental written agreement signed by Executive and the Company.

                                      -8-
<PAGE>   9

        IN WITNESS WHEREOF, the parties have executed this Agreement as of the
date and year written below.

                                        McAFEE.COM

Date: July 14, 2000                     By: /s/ Frank Gill
      -------------------                  -------------------------------------

                                        Title: Chairman - Compensation Committee

                                        EXECUTIVE:

Date: July 14, 2000                     /s/ Srivats Sampath
      -------------------               ----------------------------------------
                                        Executive's Signature

Address for Notice:
McAfee.com
-------------------------
535 Oakmead Parkway
-------------------------
Sunnyvale, CA 94085
-------------------------

                                      -9-

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