<PAGE>   1
                                                                   Exhibit 10.12


        AGREEMENT FOR AN EXCLUSIVE ALLIANCE TO DEVELOP, MANUFACTURE AND
             MARKET A CHIP-BASED SCREENING SYSTEM FOR CELL ANALYSIS

This is an agreement executed this Twenty-sixth day of October, 1999,
hereinafter the "Effective Date") between Cellomics, Inc., 635 William Pitt
Way, Pittsburgh, PA. 15238 (hereinafter CELLOMICS) and ACLARA BioSciences Inc.
1288 Pear Avenue, Mountain View, CA 94043-1432 (hereinafter ACLARA).

                                    RECITALS

Whereas CELLOMICS has expertise in drug discovery, patterning cells on
substrates, cell analyses, luminescence detection, imaging science and
informatics;

Whereas ACLARA has expertise in microfluidics, design and engineering of
microdevices in plastic, and process engineering;

Whereas CELLOMICS and ACLARA desire to form a development, manufacturing and
marketing alliance to produce a Screening System for the life sciences to
perform Cell-based Assays.

Now, therefore, in consideration of the covenants and conditions contained
herein, the Parties, intending to be legally bound, agree as follows:

1.   Definitions

1.1  "Cassette" means an assembled unit comprising an operable combination of a
     Cell Plate and Microfluidic Plate.

1.2  "Cell-based Array" means any assay in which a biological target molecule or
     organelle is analyzed in, on and [*]. The cells can be from any life form
     including but not limited to bacteria, animals and plants.

1.3  "Cell Plate" means a glass or plastic plate material having a modified
     surface that supports selective adhesion of cells in discrete regions.

1.4  "EAP" shall mean an Early Access Partner. This is a third party that has
     executed a TAP Agreement approved by the JSC pursuant to which such third
     party (i) is provided access to Prototypes during the Development Phase and
     (ii) pays a fee for having early access under the applicable TAP.

1.5  "High Content Screening (HCS)" means the activity or status of cells in the
     Cassette [*].

1.6  "High Throughput Screening (HTS)" means the measurement of single values
     that represent the average or total of a signal obtained from a single well
     in a Cassette,

CONFIDENTIAL

[*]  CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY
     BRACKETS, HAS BEEN OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND
     EXCHANGE COMMISSION PURSUANT TO RULE 406 OF THE SECURITIES ACT OF 1933, AS
     AMENDED.

                                      -1-
<PAGE>   2


     regardless of whether the signal is produced intra- or extracellularly. The
     single values will be obtained as a group of values as to different
     candidate compounds or different indications resulting from the same
     compound.

1.7  "Intellectual Property Milestone" shall be when the Parties complete a
     Prototype and the aggregate commitment from the TAP shall be [*] based on
     individual EAP fees of at least [*].

1.8  "JSC" shall mean the Joint Steering Committee, which will be composed of
     equal numbers of members from both CELLOMICS and ACLARA, not to exceed a
     total of eight, which members may be changed from time to time by the Party
     whom they represent, and to be chaired by the Project Leaders for the
     Parties.

1.9  "Liquid Transfer System" means any system used for transferring materials
     to the Cassette.

1.10 "Luminescence-based Reagents" are reagents that result in light emission
     for use in Cell-based Assays.

1.11 "Microfluidic Plate" means microfluidic device of an electrically
     non-conducting material designed to mate with the Cell Plate to [*].

1.12 "Microplate" means a standard multiwell plate most commonly of 96 or 384
     wells, but also available in 6, 12, 24, 48, 1536 and other formats with
     overall dimensions of about 3.5 x 4.5 cm.

1.13 "Program" shall mean a research program to develop a Screening System as
     set forth in the Workplan.

CONFIDENTIAL

[*]  CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY
     BRACKETS, HAS BEEN OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND
     EXCHANGE COMMISSION PURSUANT TO RULE 406 OF THE SECURITIES ACT OF 1933, AS
     AMENDED.

                                      -2-
<PAGE>   3


1.14  "Prototype" shall mean a development stage Screening System meeting all or
      most of the specifications set forth in the applicable Workplan, however,
      not in a format useful for general sale and commercial distribution. A
      Prototype is typically suitable for delivery to an EAP.

1.15  "Reader" shall mean the optical system and accompanying software developed
      for reading the Luminescence signals from the cells.

1.16  "Revenue Source" is any source of revenues to support the Program other
      than internal sources, including but not limited to government grants, EAP
      fees, funds from the other Party and funds from collaborators other than a
      Party.

1.17  "Robotics" means the mechanical units for assembling and moving the
      components necessary for performing a Cell-based Assay with a Cassette.

1.18  "Screening System" shall mean the Cassette, Robotics, Reader, Liquid
      Transfer System, software and such other integrated peripheral devices to
      conduct High Throughput and/or High Content Screening, including
      disposables. The Screening System shall be all of the hardware and
      software to provide a complete system for performing Cell-based Assays
      (except for the Luminescence-based Reagents and such other reagents as may
      be used for Cell-based Assays).

1.19  "TAP" shall mean Technology Access Program between ACLARA and CELLOMICS
      with companies which shall serve as EAPs.

1.20  "Workplan" shall list goals and tasks detailing the actual work expected
      to be done, with timelines, budget and a delineation of responsibilities.

2.   Development

      2.1  The "Field" of this collaboration is the development of an automated
           system for [*]. It is an essential term of this agreement that
           CELLOMICS agrees to work exclusively with ACLARA on any and all
           matters involving microfluids in Cell-based Assays and ACLARA agrees
           to work exclusively with CELLOMICS on any and all matters involving
           Cell-based Assays during the Program.

      2.2  This Agreement will become effective on the Effective Date.

      2.3  CELLOMICS is attempting to obtain [*] to be permitted to utilize [*]
           to support ACLARA's research effort for the [*] of the Program.
           Whether or not CELLOMICS ever obtains such approval from [*],
           CELLOMICS is obligated to and hereby commits to pay [*] to support
           ACLARA's said research for the [*] of the

CONFIDENTIAL

[*]  CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY
     BRACKETS, HAS BEEN OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND
     EXCHANGE COMMISSION PURSUANT TO RULE 406 OF THE SECURITIES ACT OF 1933, AS
     AMENDED.

                                      -3-
<PAGE>   4


           Program in [*]. During the period in which CELLOMICS is paying
           ACLARA, ACLARA shall provide CELLOMICS with a statement of the cost
           allocated to the Program as determined in accordance with reasonable
           accounting procedures used internally by ACLARA within thirty (30)
           days of receipt of the quarterly check due ACLARA. The dates on which
           such payments are due may be changed in accordance with the date of
           initiation of work by ACLARA and the rate at which employees are
           hired by ACLARA to perform the Program.

     2.4   During the first year of the term of this agreement ("First Year"),
           the Parties agree to work in accordance with the Workplan set forth
           in Appendix A, with the goal to have a Prototype of the Cassette by
           the first anniversary of the Effective Date. The goal during the [*]
           is to optimize the Cell Plate and Microfluidic Plate design and
           interfacing to enable fabrication of a functional Cassette. This
           Cassette is intended to have the specifications for and serve as a
           testbed for a [*]. In addition, it is intended that the Parties will
           use this Cassette as a working Prototype in a TAP program.
           Development of the Cassette Prototype will be directed to enable:
           [*]. During the First Year and thereafter, each Party will provide
           written reports with thirty (30) days of the end of each calendar
           quarter of the progress it has made during such quarter and the work
           to be performed in the next quarter and a written summation of the
           work accomplished at the end of each calendar year within thirty (30)
           days of the end of such calendar year.

     2.5.  Notwithstanding the intention to achieve the goals of the Workplan
           for the First Year, it is understood that in order to staff the
           Program, ACLARA and CELLOMICS will be required to hire new personnel
           or transfer existing personnel as they may become available. While
           each Party will act diligently to staff the Program in accordance
           with the Program's needs and available funding, the timing of such
           hires or transfers is not completely within the control of the
           Parties and the schedule of the Workplan may be delayed. At each
           quarterly meeting of the JSC, the accomplishment of the previous
           quarter, and the available funding, committed or to be committed,
           will be evaluated and the Workplan modified, if necessary, in light
           of the circumstances then pertaining.

           2.5.i.  If prior to the occurrence of the Intellectual Property
                   Milestone there appears to either Party to be an insufficient
                   Revenue Source at that time or in the reasonably foreseeable
                   future to support the Program in the amounts required by each
                   Party for its performance, the JSC shall review the situation
                   and report to the respective CEO's its recommendation as to
                   how to proceed within sixty (60) days of notification by
                   either Party that such Party believes there is an
                   insufficient Revenue Source to support the Program. If the
                   CEOs cannot agree within sixty (60) days of receiving

CONFIDENTIAL

[*]  CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY
     BRACKETS, HAS BEEN OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND
     EXCHANGE COMMISSION PURSUANT TO RULE 406 OF THE SECURITIES ACT OF 1933, AS
     AMENDED.

                                      -4-
<PAGE>   5


                  notification from the JSC as to how to proceed, either Party
                  may terminate this Agreement upon giving prompt notice of
                  termination to the other Party without obligation to license
                  the other party under the terminating Party's intellectual
                  property. If the Program is terminated for other than material
                  breach prior to the completion of the Intellectual Property
                  Milestone, the parties will negotiate in good faith to allow a
                  continuing party to continue the Program.

         2.5.ii.  Notwithstanding Paragraph 2.5.i, after the Intellectual
                  Property Milestone has been achieved, the terminating Party
                  will be obligated to license the continuing Party under the
                  terminating Party's intellectual property to continue to
                  develop and commercialize the Prototype and Screening System
                  as hereinafter provided. Upon termination by one Party for
                  other than material breach, with the Intellectual Property
                  Milestone having been achieved, the other Party may continue
                  the Program and the terminating Party agrees to enter into
                  negotiations within thirty (30) days of such termination with
                  the other Party over the terms of such license which the
                  terminating Party is obligated to license to the continuing
                  Party under its intellectual property, both background and
                  foreground, on reasonable terms and conditions to make, use
                  and sell Screening Systems substantially conforming to the
                  Screening System which was to be jointly developed.

       2.6   Assuming financing is obtained as required to support the Program
             for the second and third years of the term of this Agreement, or
             such other periods in which the goals of these years are to be
             fulfilled as determined by the JSC, a Screening System will be
             developed, which is intended to offer a complete solution to the
             need for flexibility in Cell-based Assays starting with an initial
             focus on [*]. The Screening System will be designed to have the
             ability to provide a complete portfolio of assays including [*].
             The Screening System will offer a ready-to-use and easy-to-use
             solution for the life scientist and further will promote
             penetration of sophisticated Cell-based Assays HCS in drug
             discovery. The target pharmaceutical customer for the Screening
             System is an entity with significant biological expertise in
             primary screening, a therapeutic group or a specialty such as [*].

       2.7   The development program for [*] of the term of this agreement is
             set forth in Appendix B with the intention of developing a
             Screening System. The 3D Cassette will have a high density plumbing
             architecture for selective addressing of a high density of
             micro-arrayed cells on the Cell Plate. The initial design and
             prototypes will focus on multiples of 96 well patterns in a
             footprint ranging from [*].

       2.8   CELLOMICS shall be responsible for identifying sources for the
             Robotics, Reader and such other equipment, which is not available
             from or to be developed

CONFIDENTIAL

[*]  CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY
     BRACKETS, HAS BEEN OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND
     EXCHANGE COMMISSION PURSUANT TO RULE 406 OF THE SECURITIES ACT OF 1933, AS
     AMENDED.

                                      -5-
<PAGE>   6


            by the Parties to this agreement. Selection of one or more sources
            for providing the additional equipment will begin not later than
            four (4) months after a Cassette Prototype has been shown to be
            satisfactory to the Parties. CELLOMICS shall submit to ACLARA a list
            of potential sources of producing the components of the Screening
            System not already being produced by either ACLARA or CELLOMICS.
            ACLARA and CELLOMICS shall mutually agree on the priority in which
            these sources are to be approached, and additional candidates added,
            neither party shall unreasonably withhold such agreement. Such third
            party(s) and the terms upon which they agree to participate in
            developing the Screening System shall be proposed and negotiated by
            CELLOMICS and shall be subject to the review, but not the approval
            of the JSC.

      2.9   In [*] of the term of this Agreement, the Parties will direct their
            efforts to the development of a Screening System commercial product.
            The Prototype developed in [*] is to be taken through the final
            phase of the product development cycle and to establish
            manufacturing, marketing and sales.

      2.10  A complete Screening System will include all the components required
            by a user to take a library of compounds stored in a Microplate
            format and screen the library of compounds against a target,
            producing a data set in a standard database format for ease of
            access. The responsibilities of the Parties as to the following
            components that are required to accomplish this goal are:

         -  CELLOMICS
         [*]

         -  ACLARA
         [*]

3.    Funding

      3.1   A budget is set forth for the First Year in Appendix B. Promptly
            after execution of this Agreement, the Parties will submit a
            proposed budget for [*], which budget shall be subject to review,
            modification, and approval by the JSC. These budgets will be the
            basis for [*] and provide for the division of money received from
            [*] between the Parties.

CONFIDENTIAL

[*]  CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY
     BRACKETS, HAS BEEN OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND
     EXCHANGE COMMISSION PURSUANT TO RULE 406 OF THE SECURITIES ACT OF 1933, AS
     AMENDED.

                                      -6-
<PAGE>   7


            3.2.  Not later than three (3) months after initiation of the
                  Workplan, the JSC will prepare and submit a budget to [*]
                  based on the budgets submitted by the Parties requesting an
                  increase in the total funding for both companies to accelerate
                  the development of the Screening System. Not later than [*],
                  the Parties will prepare and submit a [*] grant. The budget
                  may reflect provision for sources of components of the
                  Screening System, which the Parties do not intend to develop
                  or supply.

            3.3   CELLOMICS and ACLARA will jointly prepare a TAP to attract
                  companies as EAPs that will fund the Program. CELLOMICS and
                  ACLARA will jointly make presentations to the pharmaceutical
                  industry. The Parties will develop jointly the basic terms for
                  a TAP, which shall be the basis for entering into agreements
                  with EAPs. The TAP will be developed not later than one (1)
                  month from the completion of a satisfactory Cassette
                  Prototype.

      4.    Commercialization plan

            4.1.  Final product development and component manufacturing: The
                  Prototype completed in [*] and delivered as a beta test system
                  to at least [*] EAPs in [*] will be developed into a Screening
                  System component for manufacturing. ACLARA will be responsible
                  for final engineering and establishment of manufacturing
                  capability for the Microfluidic Plate. ACLARA is developing a
                  [*], and if applicable, ACLARA will contribute this to the
                  Screening System. If incremental development is required to
                  render this [*] applicable to the Screening System, the JSC
                  may adjust the Workplan accordingly. CELLOMICS will be
                  responsible for Cell Plates, all reagents, assays, and
                  protocols. CELLOMICS will work to ensure that the components
                  which neither Party intends to produce are made available from
                  a third party and are available for commercialization of the
                  Screening System. CELLOMICS will be responsible for the final
                  development and manufacturing of the remaining components of
                  the Screening System.

            4.2.  Manufacturing of the integrated system: The final
                  manufacturing, packaging and delivery of [*] and other
                  Cell-based Assay reagents, Cassettes and Screening Systems to
                  customers will be the responsibility of CELLOMICS. Prior to
                  the initiation of manufacturing of a Cassette, the Parties
                  will enter into a supply agreement in which ACLARA will be
                  responsible for delivering to CELLOMICS, or a third party
                  designated by CELLOMICS, sufficient quantities of Microfluidic
                  Plates for packaging with Cell Plates. Such supply agreement
                  will provide for indemnification of the other Party on
                  conventional terms for the intentional, willful, or negligent
                  act or failure to act of one Party, giving rise to a claim
                  against the other Party. The supply terms for ACLARA's
                  delivery to CELLOMICS shall be conventional, giving due regard
                  to

CONFIDENTIAL

[*]  CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY
     BRACKETS, HAS BEEN OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND
     EXCHANGE COMMISSION PURSUANT TO RULE 406 OF THE SECURITIES ACT OF 1933, AS
     AMENDED.

                                      -7-
<PAGE>   8


          the size of the batches required, the effect of volume on price,
          agreements with third parties for manufacture of the Microfluidic
          Plates and the time required for initiating a run of Microfluidic
          Plates. CELLOMICS will provide ACLARA with sales projections on a
          rolling basis. Inventory shall be the responsibility of CELLOMICS.

     4.3. Deliver Production Systems: For all life science applications,
          CELLOMICS will have full responsibility for ensuring that all
          components of the Screening System are available for marketing,
          marketing of the Screening System, and providing support for the
          Screening Systems and its components. The target markets for these
          systems will include, but not be limited to pharmaceutical discovery
          and development, clinical diagnostics, agriculture biotech, and basic
          biomedical research.

     4.4. Product Designation: ACLARA's name and trademark shall appear
          prominently on the Microfluidic Plate and CELLOMICS shall give due
          credit for ACLARA's contributions in its labeling, advertising and
          promotion. Statements made by CELLOMICS concerning ACLARA shall be
          subject to review and approval by ACLARA, which approval shall not be
          unreasonably withheld.

     4.5. Reader Designation: CELLOMICS's name and trademark shall be use din a
          primary capacity and ACLARA's name and trademark shall be use din a
          secondary capacity on the Reader and CELLOMICS shall give due credit
          for ACLARA's contributions in its labeling, advertising and promotion.
          Statements made by CELLOMICS concerning ACLARA shall be subject to
          review and approval by ACLARA, which approval shall not be
          unreasonably withheld.

5.   Revenue Sharing

     5.1  During the development and commercialization phase, the money obtained
          from third parties from a Revenue Source shall be divided to ensure
          that each Party's expenditure of its own money on a JSC approved
          Workplan is minimized. The exact division of [*] will be decided at
          the time of [*]. The division of TAP fees will be defined by the JCS,
          and approved by the CEO of both Parties, and written into a separate
          agreement between CELLOMICS and ACLARA before a TAP agreement is
          consummated. Funding from a collaborator other than the other Party
          will primarily be used for the purposes of the collaboration.

     5.2  Not later than the end of [*] the Parties shall initiate negotiations
          as to the division of income resulting from the sales of Screening
          Systems and its components. The division of the income will first be
          considered by the JSC with final approval of the CEO's from CELLOMICS
          and ACLARA. ACLARA shall receive from CELLOMICS [*] and a reasonable
          profit margin for items manufactured or supplied by ACLARA;
          Considerations in determining the division of remaining

CONFIDENTIAL

[*]  CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY
     BRACKETS, HAS BEEN OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND
     EXCHANGE COMMISSION PURSUANT TO RULE 406 OF THE SECURITIES ACT OF 1933, AS
     AMENDED.

                                      -8-
<PAGE>   9


          income shall be the financial contribution of each of the Parties,
          except to the extent the Parties have been reimbursed any portion of
          their contribution by a Revenue Source, the novelty of their
          contributions, the value of the intellectual property that protects
          components of the Screening Systems, the competitive advantages
          provided by the contributions of the two Parties, the responsibilities
          of the two Parties in manufacturing, marketing and supporting the
          ongoing expenditures, the risks involved with the continuing
          investments, and the like. The income to ACLARA shall not be less than
          a reasonable royalty on patents and know-how contributed by ACLARA
          with the base being Screening Systems and components, where the
          royalty may vary as to whole Screening Systems and as to individual
          disposable Screening System components. Royalty shall not be paid
          twice for the same component of the Screening System. If there is no
          agreement between the Parties, the matter shall be given to mediation
          as provided for hereinafter. The exact mechanism for delivering the
          value to the Parties will be defined as the program proceeds toward
          commercialization. It may involve strict revenue sharing, licensing,
          royalties or some combination that will be defined by the JSC.

6.   Public Relations

     6.1  All press releases created by an originating Party shall be submitted
          to the other Party for approval and shall not be released without the
          prior written approval of the other Party. In the event of a dispute,
          the matter shall be submitted to the CEOs of the Parties and if the
          issue cannot be reconciled, there shall be no press release containing
          disputed subject matter.

     6.2  Prior to commercial introduction of a Screening System, all public
          presentation relating to this Program, not already made public,
          including Web postings, corporate presentations, investor relations,
          and marketing collateral, must be approved by the other Party, such
          approval not to be unreasonably withheld.

7.   Intellectual Property

     7.1  Ownership. Each of the Parties will own all intellectual property and
          inventions made by individuals who have a duty to assign to that Party
          and will jointly own all inventions co-invented by at least one
          inventor having a duty to assign to each Party. The Party owning the
          invention shall have the exclusive right to file worldwide for patent
          applications covering the invention.

     7.2  Joint Intellectual Property. CELLOMICS and ACLARA will jointly
          determine the advisability of filing a patent application. The JSC
          will appoint one of the Parties to be responsible to prepare, file,
          prosecute diligently and maintain such application(s). The Parties
          will share equally all reasonable costs incurred in

CONFIDENTIAL

                                      -9-
<PAGE>   10


          connection with such activities (i.e., the non-prosecuting Party will
          promptly reimburse the prosecuting Party), provided, however, that
          either Party may avoid its responsibility for such costs by assigning
          its rights in such Joint Intellectual Property to the other Party. In
          such an event, the other Party may decide at its sole discretion
          whether or not to file or continue prosecution of such applications.
          Also, the assigning Party will provide reasonable assistance to the
          assignee to facilitate the filing and prosecution of all such
          applications. Joint Intellectual Property will be jointly owned, and
          either Party is free to use such Joint Intellectual Property as it
          sees fit, outside the Field of this Agreement. CELLOMICS shall have
          the exclusive right to use such Joint Intellectual Property within the
          Field of this Agreement for the lessor of i) a period of five (5)
          years from the first commercial release of the Screening System, or
          ii) eight years (8) from the Effective Date. Thereafter, either Party
          may use such Joint Intellectual Property without accounting to the
          other Party.

     7.3  Rights. All inventions owned by ACLARA developed as part of the
          program having application to the Cell Plate shall be licensed to
          CELLOMICS on reasonable terms and conditions, if at the time of filing
          of a patent application for such invention, CELLOMICS agrees to pay
          [*] of the out-of-pocket costs of the filing, prosecution and
          maintenance of such application, continuing applications, foreign
          analogs, and Letters Patent issuing thereon. All inventions owned by
          CELLOMICS developed as part of the collaboration having application to
          the Microfluidic Plate shall be licensed to ACLARA on reasonable terms
          and conditions, if at the time of filing of a patent application for
          such invention, ACLARA agrees to pay [*] of the out-of-pocket costs of
          the filing, prosecution and maintenance of such application,
          continuing applications, foreign analogs, and Letters Patent issuing
          thereon.

     7.4  Licensing of Foreground technology. Technical know-how and patent
          rights developed as part of the Program shall be available on
          reasonable terms and conditions after termination of this Agreement in
          the event that one Party wishes to continue the Program.

     7.5  Licenses of Background Technology. Technical know-how and patent
          rights developed prior to initiation of the Program or outside of the
          Program may be licensed for a Screening System developed in the
          Program as set forth in Section 2.5.

     7.6  Label License. All products supplied by ACLARA to CELLOMICS will
          include a label license, granting CELLOMICS a license under ACLARA's
          intellectual property to use, offer to sell, and sell any such
          products for use in the Field, such label license being transferable
          to the purchasers of such products.

CONFIDENTIAL

[*]  CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY
     BRACKETS, HAS BEEN OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND
     EXCHANGE COMMISSION PURSUANT TO RULE 406 OF THE SECURITIES ACT OF 1933, AS
     AMENDED.

                                      -10-
<PAGE>   11


     7.7. Confidentiality. All technical and business information given the
          recipient Party by the disclosing Party shall be assumed to be in
          confidence and if disclosed orally, shall be reduced to writing and
          delivered to the recipient within thirty (30) days of disclosure.
          Information received in confidence shall be used solely for the
          purposes of this Agreement and shall be disclosed to others who assume
          like duties of confidentiality. The restrictions on use and disclosure
          shall not apply where the information is or becomes generally known
          without failure on the part of the recipient; was known to the
          recipient prior to receipt from the discloser; or is given to the
          recipient by a third party who has the right to disclose the
          information, without restriction on use or disclosure. The obligations
          on use and disclosure shall terminate five (5) years from the
          termination of the Program.

8.   Surviving Rights/Termination

     8.1  Surviving Rights and Duties. The right to obtain licenses to
          intellectual property rights covering technology employed in the
          Program as provided for in this Agreement shall survive termination of
          this Agreement. Either Party shall have the right to a license from
          the other Party if such license is requested within two (2) years
          after termination of this Agreement.

     8.2  Termination. This Agreement may be terminated by either Party in the
          event of material breach by the other Party, upon giving sixty (60)
          days prior written notice of the intent to terminate, which
          termination will be effective if the breaching Party has not taken
          reasonable steps to correct the material breach. The right to
          terminate is in addition to all other rights the non-breaching Party
          may have against the breaching Party.

     8.3  Permissive termination. Either Party may terminate this Agreement,
          with the acceptance of the other.

9.   Governance

     9.1  Joint Steering Committee. The Program will be governed by the JSC. The
          JSC shall consist of at least one senior executive, one business
          director, and one technical director from each Party. The JSC will
          meet at least once per quarter, alternating between locations selected
          by ACLARA and CELLOMICS, to oversee activities under a Workplan. In
          particular, the JSC will monitor and support collaboration and/or
          supply relationships existing between ACLARA and CELLOMICS, review,
          recommend modifications to, and oversee the implementation of active
          Workplans, define deliverables for TAPs, approve EAPs, review the
          commercial feasibility of Screening Systems being developed under a
          Workplan, review the progress of the Workplan and funding, offer
          modifications to the Workplan in light of changed circumstances,
          discuss new commercial opportunities and develop the objectives and
          terms for additional Programs between the Parties that may be pursued.
          The JSC shall have the authority to make reasonable alterations or
          amendments to the Workplan, which

CONFIDENTIAL

                                      -11-
<PAGE>   12


               will be considered final after reduction to writing and
               attachment to the Agreement. Significant alterations to the
               Workplan must be approved by the CEO of both Parties. The JSC
               shall have the authority to recommend alterations or amendments
               to this Agreement, which shall not become final until reduced to
               writing and signed by the CEO of each of the Parties. Except as
               otherwise expressly provided herein, decisions of the JSC will be
               made by consensus.

          9.2  Dispute resolution. Should disputes arise, the Parties agree to
               negotiate in good faith to resolve the disputes. Disputes that
               cannot be resolved by the JSC within a reasonable period shall be
               submitted to the CEOs of the Parties. If agreement is still not
               reached, the Parties agree to submit disputes to mediation in
               accordance with the section 9.3, "Mediation", prior to seeking
               any other remedy.

          9.3  Mediation. If the Parties are unable to resolve by negotiation
               within forty-five days of the disputing Party's written request
               for dispute resolution (or such other time period expressly set
               forth in this Agreement), or if the Parties fail to meet within
               twenty (20) days after such notice, the Parties shall endeavor to
               settle the dispute by mediation administered by the American
               Arbitration Association ("AAA") pursuant to the Commercial
               Mediation Rules of the AAA the time of submission prior to
               resorting to any other remedy. Mediation shall be held in a
               location to be decided later. The mediator appointed to assist
               the Parties must possess such credentials as qualify said
               mediator as (1) either an expert in the field being mediated or
               (2) at a minimum as reasonably familiar with the industries and
               specific applications as will enable the mediator to quickly
               understand and assist the Parties in dealing with the issues that
               are in dispute. Notwithstanding the foregoing, to the extent that
               any controversy or claim hereunder gives rise to a prayer for
               injunctive relief, equitable action or specific performance, the
               aggrieved Party shall have the right to commence such an action
               in any court of competent jurisdiction.

10.  Representations and Warranties

10.1 Authority. Each Party hereby represents and warrants to the other that it
     has full power and authority to enter into this agreement and to consummate
     the transactions contemplated hereby. This agreement has been duly executed
     and delivered and constitutes a valid and binding obligation of the Party,
     enforceable against it in accordance with its terms, except as such
     enforceability may be limited by bankruptcy, insolvency, reorganization,
     fraudulent conveyance, moratorium or similar laws affecting creditors'
     rights generally from time to time in effect or by general equitable
     principles.

10.2 Corporate Organization and Authority. Each Party hereby represents and
     warrants to the other that it is a corporation duly organized, validly
     existing and in good standing under the laws of Delaware as to CELLOMICS
     and California as to ACLARA and has all corporate power and authority to
     carry on its business as

CONFIDENTIAL

                                      -12-
<PAGE>   13


        now being conducted and to own its properties, is duly qualified and in
        good standing to do business in every jurisdiction in which such
        qualification is necessary because of the nature of the property owned,
        leased or operated by it or the nature of the business conducted by it
        except where the failure to be so qualified would not have a material
        adverse effect.

10.3    Ability to Carry Out the Agreement: Consents and Waivers. Each Party
        hereby represents and warrants to the other that the execution and
        delivery of this agreement does not, and the consummation of the
        transactions contemplated hereby will not, conflict with, or result in
        any violation of or default (with or without notice or lapse of time, or
        both) under, or give rise to a right of termination under, or accelerate
        the performance required by, or result in the creation of any lien,
        security interest, charge, increase in liability or other encumbrance
        upon any of its assets under, any provision of:

                (i)   any law, statute, rule, regulation or judicial or
                      administrative decision;

                (ii)  any certificate of incorporation or by-laws;

                (iii) any mortgage, deed of trust, lease, note, shareholders'
                      agreement, bond, indenture, contract or other instrument
                      or agreement; or

                (iv)  any judgment, order, writ, injunction or decree of any
                      court, governmental body, administrative agency or
                      arbitrator relating to it;

                (v)   other than conflicts, violations, defaults, right of
                      termination or encumbrances which could not reasonably be
                      expected to have a material adverse effect on the
                      enforceability or validity or the agreement.

10.4    Litigation. Each Party hereby represents and warrants to the other that
        there is no action, suit, or governmental, administrative or regulatory
        proceeding or investigation pending or, to the knowledge of the Party,
        threatened against it at law, in equity or otherwise, in, before, or by
        any court or governmental agency or authority which could reasonably be
        expected to have a material adverse effect on this agreement or the
        transactions contemplated therein. ACLARA is presently involved solely
        in two pieces of litigation; being sued for misappropriation of trade
        secrets; and suing for patent infringement.

10.5    Year 2000. Each Party hereby represents and warrants to the other that
        software, hardware, equipment and systems owned, leased or licensed by
        it and used in the conduct of its business are Year 2000 Compliant.

CONFIDENTIAL

                                      -13-
<PAGE>   14
10.6    Regulatory Filings. Each of the Parties hereto will furnish to the other
        Party hereto such necessary information and reasonable assistance as
        such other Party may reasonably request in connection with its
        preparation of necessary filings or submissions to any governmental
        entity.

10.7    Announcement. Neither Party nor their respective affiliates will issue
        any press release or other public announcement with respect to this
        agreement or the transactions contemplated hereby without the prior
        written approval of the other Party hereto (such approval not to be
        unreasonably withheld, conditioned or delayed).

10.8    Indemnification. Each Party agrees to defend, indemnify and hold
        harmless the other and its respective successors and assigns against and
        in respect of:

        (a) any and all losses, damages, deficiencies or liabilities ("Damages")
            caused by, resulting or arising from or otherwise relating to any
            material failure by a Party to perform or otherwise fulfill or
            comply with any undertaking or other agreement or obligation to be
            performed, fulfilled or complied with by the Party resulting from
            its gross negligence, willful misconduct or arising from or
            otherwise relating to any material breach of any representation or
            warranty of the Party contained in this agreement.

10.9    Entire Agreement. The Agreement (including the appendices attached
        hereto, all of which are part hereof) contain the entire understanding
        of the Parties hereto with respect to the subject matter contained
        herein, and supersede and cancel all prior agreements, negotiations,
        correspondence, undertakings and communications of the Parties, oral or
        written, respecting such subject matter. There are no restrictions,
        promises, representations, warranties, agreements or undertakings of any
        Party hereto with respect to the transactions under this Agreement other
        than those set forth herein or therein or made hereunder or thereunder.

10.10   Amendments. This agreement may be amended only by a written instrument
        executed by the Parties or their respective successors or assigns.

10.11   Headings; References. The article and section headings contained in this
        agreement are for reference purposes only and shall not affect in any
        way the meaning or interpretation of this agreement. All references
        herein to "Articles," "Sections," "Schedules," or "Appendices" shall be
        deemed to be references to Articles or Sections hereof or Schedules or
        Appendices hereto unless otherwise indicated.

11.     Notices


        11.1.  Notices may be given to an officer of a Party by;

CONFIDENTIAL

                                      -14-
<PAGE>   15


personal delivery, fax or registered mail addressed as follows:
overnight delivery by an internationally recognized courier service

If to ACLARA Biosciences Inc.:
Joseph M. Limber
President and CEO

ACLARA Biosciences, Inc.
1288 Pear Avenue
Mountain View, CA 94043-1432
FAX (650) 210-1210

If to CELLOMICS, Inc.:
D. Lansing Taylor
President and CEO
CELLOMICS, Inc.
635 William Pitt Way

Pittsburgh, PA 15238
FAX (412) 826-3896

12.  Binding Effect

12.1 This agreement shall inure to the benefit of and be binding on each Party's
     successors in interest and assigns.

13.  Assignment

13.1 Either Party may assign this agreement only in connection with the sale or
     disposition of the entire business of such Party or that portion to which
     this agreement pertains. Either Party may assign this Agreement to an
     Affiliate(s) without permission of the other Party. Affiliate shall mean an
     entity controlling, controlled by, or under common control with a Party to
     this Agreement.

14.  Governing Law

14.1 This Agreement shall be interpreted in accordance with the local laws of
     the Party defending any action brought under this Agreement.

[Signature page Follows]

CONFIDENTIAL

                                      -15-
<PAGE>   16


 Signature Page for Agreement For An Exclusive Alliance To Develop, Manufacture
           And Market A Chip-Based Screening System For Cell Analysis

In Witness Whereof, this Agreement has been executed in multiple counterparts,
each of which shall constitute an original Agreement, on behalf of the Parties
by their authorized officers as of the date first written above:

CELLOMICS, INC.

Signature /s/ D. LANSING TAYLOR
          ------------------------------

Print D. Lansing Taylor
      ----------------------------------

Title President & CEO
      ----------------------------------

Date 10/26/99
     -----------------------------------

ACLARA BIOSCIENCES INC.

Signature /s/ JOSEPH M. LIMBER
          ------------------------------

Print Joseph M. Limber
      ----------------------------------

Title President & CEO

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

Date October 26, 1999
     -----------------------------------

CONFIDENTIAL

                                      -16-
<PAGE>   17



                                   APPENDIX A

WORKPLAN
[*]

CONFIDENTIAL

[*]  CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY
     BRACKETS, HAS BEEN OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND
     EXCHANGE COMMISSION PURSUANT TO RULE 406 OF THE SECURITIES ACT OF 1933, AS
     AMENDED.

                                      -17-

[*]

CONFIDENTIAL

[*]  CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY
     BRACKETS, HAS BEEN OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND
     EXCHANGE COMMISSION PURSUANT TO RULE 406 OF THE SECURITIES ACT OF 1933, AS
     AMENDED.

                                      -18-

[*]

CONFIDENTIAL

[*]  CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY
     BRACKETS, HAS BEEN OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND
     EXCHANGE COMMISSION PURSUANT TO RULE 406 OF THE SECURITIES ACT OF 1933, AS
     AMENDED.

                                      -19-


                                   APPENDIX B

                                  FUNDING PLAN

[*]

CONFIDENTIAL

[*]  CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY
     BRACKETS, HAS BEEN OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND
     EXCHANGE COMMISSION PURSUANT TO RULE 406 OF THE SECURITIES ACT OF 1933, AS
     AMENDED.

                                      -20-

<PAGE>   18


[*]

CONFIDENTIAL

[*]  CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY
     BRACKETS, HAS BEEN OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND
     EXCHANGE COMMISSION PURSUANT TO RULE 406 OF THE SECURITIES ACT OF 1933, AS
     AMENDED.

                                      -21-

[*]

CONFIDENTIAL

[*]  CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY
     BRACKETS, HAS BEEN OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND
     EXCHANGE COMMISSION PURSUANT TO RULE 406 OF THE SECURITIES ACT OF 1933, AS
     AMENDED.

                                      -22-

[*]

CONFIDENTIAL

[*]  CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY
     BRACKETS, HAS BEEN OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND
     EXCHANGE COMMISSION PURSUANT TO RULE 406 OF THE SECURITIES ACT OF 1933, AS
     AMENDED.

                                      -23-