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CERTAIN MATERIAL (INDICATED BY AN ASTERISK) HAS BEEN OMITTED FROM THIS DOCUMENT
PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT. THE OMITTED MATERIAL HAS BEEN
FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION.

                                                                   EXHIBIT 10.21


                            NON-ASSERTION AGREEMENT


     This AGREEMENT is made effective this 7th day of February, 1997 by and
between GEN-PROBE INCORPORATED, having a place of business at 9880 Campus Point
Drive, San Diego, California 92121, United States of America ("GEN-PROBE") and
ORGANON TEKNIKA B.V., having a place of business at Boseind 15, 5281 RM Boxtel,
The Netherlands ("TEKNIKA"), who agree as follows:

Section 1.0 Recitals

     1.1  GEN-PROBE and TEKNIKA each possess their own Patent Rights regarding
transcription-based amplification which are listed in Appendix A. GEN-PROBE
holds an exclusive license to the Stanford Patent under the Stanford Agreement.

     1.2  GEN-PROBE and TEKNIKA each desire to avoid legal actions between
themselves relating to each other's Patent Rights and with regard to the
Stanford Patent and to minimize costs associated with possible patent
interference proceedings and other possible adversarial activities in any
national patent office or in the European Patent Office concerning each other's
Patent Rights or the Stanford Patent.

     1.3  GEN-PROBE and TEKNIKA each desire to allow the other party, and
Licensees of the other party, to practice transcription-based amplification with
immunity from legal action for actually or allegedly infringing each other's
Patent Rights.

     1.4  GEN-PROBE and TEKNIKA each desire to resolve any pending disputes
between the two parties concerning Patent Rights or the Stanford Patent, so as
to allow each party to commercialize products based on transcription-based
amplification without threat of legal action from the other party.

Section 2.0 Definitions

     2.1  "GEN-PROBE Patent Rights" shall mean the patents and patent
applications set forth in Appendix A hereto under the heading "GEN-PROBE Patent
Rights", together with any unlisted patents and patent applications from which
any of the listed patents claim priority, and any and all patents that have
issued or in the future issue from the foregoing patents and patent
applications, including utility, model and design patents and certificates of
invention, and all divisionals, continuations, continuations-in-part, reissues,
renewals, re-examinations, extensions or additions thereof claiming priority
from any of the foregoing patents or patent applications heretofore or hereafter
having legal force in any country to the extent that GEN-PROBE has the right to
grant licenses, immunities, or rights thereunder or to assert rights thereunder.

Explicitly and specifically excluded from GEN-PROBE Patent Rights are rights to
specific nucleic acid sequences described in or subsequently claimed by the
above patents and patent applications and all continuations,
continuations-in-part, divisionals, re-examinations, renewals, reissues,
additions, and extensions thereof claiming priority from any of the patents or
patent applications set forth in Appendix
<PAGE>
A heretofore or hereafter having legal force in any country to the extent that
either party has the right to grant licenses, immunities, or rights thereunder
or to assert rights thereunder.

GEN-PROBE shall disclose in Appendix A any limitations on its rights to grant
licenses, immunities, or rights under the GEN-PROBE Patent Rights or to assert
rights thereunder.

     2.2  "TEKNIKA Patent Rights" shall mean the patents and patent applications
set forth in Appendix A hereto under the heading "TEKNIKA Patent Rights",
together with any unlisted patents and patent applications from which any of
the listed patents claim priority, and any and all patents that have issued or
in the future issue from the foregoing patents and patent applications,
including utility, model and design patents and certificates of invention, and
all divisionals, continuations, continuations-in-part, reissues, renewals,
extensions or additions thereof claiming priority from any of the foregoing
patents or patent applications heretofore or hereafter having legal force in
any country to the extent that TEKNIKA has the right to grant licenses,
immunities, or rights thereunder or to assert rights thereunder.

Explicitly and specifically excluded from TEKNIKA Patent Rights are rights to
specific nucleic acid sequences described in or subsequently claimed by the
above patents and patent applications and all continuations,
continuations-in-part, divisionals, re-examinations, renewals, reissues,
additions, and extensions thereof claiming priority from any of the patents or
patent applications set forth in Appendix A heretofore or hereafter having legal
force in any country to the extent that either party has the right to grant
licenses, immunities, or rights thereunder or to assert rights thereunder.

TEKNIKA shall disclose in Appendix A any limitations on its rights to grant
licenses, immunities, or rights under the TEKNIKA Patent Rights or to assert
rights thereunder.

     2.3  "Patent Rights" shall mean GEN-PROBE Patent Rights and/or TEKNIKA
Patent Rights as the context requires.

     2.4  "Stanford Patent" shall mean U.S. Patent 5,437,990 and all
continuations, continuations-in-part, divisionals, re-examinations, renewals,
reissues and extension of patents or patent applications filed in the United
States of America or in any other country which claim priority from or are
derived from U.S. patent application Serial Number 80,479; filed July 31, 1987.

     2.5  "GEN-PROBE Version" shall mean transcription-based nucleic acid
amplification using [***].

     2.6  "TEKNIKA Version" shall mean transcription-based nucleic acid
amplification using [***]

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          [***].

          2.7  "Thermostable Version" shall mean transcription-based nucleic
acid amplification conducted at a temperature of [***].

          2.8  "Version" shall mean the GEN-PROBE Version or the TEKNIKA
Version as the context requires.

          2.9  "Licensees" shall mean parties which are granted licenses by
TEKNIKA or GEN-PROBE to Patent Rights owned or controlled by TEKNIKA or
GEN-PROBE respectively.

          2.10 "Stanford Agreement" shall mean the existing agreement between
GEN-PROBE and Stanford University (effective August 1, 1988: Stanford Docket
S87-012).

          2.11 Insofar as issues regarding alleged infringement of particular
transcription-based amplification processes have not been mutually agreed to by
the parties, and removal of the need to do so is a major purpose of this
Agreement, for simplicity and the mutual convenience of the parties the term
"Product" shall mean a product covered or alleged to be covered by the Stanford
Patent or the Patent Rights listed in Appendix A.

          2.12 "Affiliate" shall mean any corporation, company, or other
business entity which directly or indirectly controls, is controlled by, or is
under common control with a party to this Agreement. For this purpose, control
means ownership or control, either direct or indirect, of at least fifty
percent (50%) of the voting stock or other ownership interest of the other
entity, or the party that directly or indirectly possesses the power to direct
or cause the direction of the management and policies of the other entity by
any means whatsoever.

Section 3.0. Non-Exclusive Immunity Grants

          3.1  GEN-PROBE grants to TEKNIKA, and to TEKNIKA's Affiliates and
Licensees, world-wide, non-exclusive immunity from legal action under the
GEN-PROBE Patent Rights to make, use and/or sell Products based on,
incorporating or utilizing the TEKNIKA Version and/or a Thermostable Version.
GEN-PROBE's grant of immunity under this section shall not be transferable by
said Licensees to additional third parties without GEN-PROBE's prior written
approval.

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<PAGE>
          3.2 TEKNIKA grants to GEN-PROBE, and to GEN-PROBE's Affiliates and
Licensees, world-wide, non-exclusive immunity from legal action under the
TEKNIKA Patent Rights to make, use and/or sell Products based on, incorporating
or utilizing the GEN-PROBE Version and/or a Thermostable Version. TEKNIKA's
grant of immunity under this section shall not be transferable by said
Licensees to additional third parties without TEKNIKA's prior written approval.

          3.3. GEN-PROBE agrees not to practice the TEKNIKA Version and TEKNIKA
agrees not to practice the GEN-PROBE Version of transcription-based
amplification, and each agrees in any license to its Patent Rights to require
its Licensees not to practice the other party's Version of transcription-based
amplification.

GEN-PROBE and TEKNIKA each agree to permit at the request of the other party an
annual review of its manufacturing records (and other records as may be
required) by an impartial, technically qualified third party to verify
compliance with the provisions of Section 3.3 of this Agreement. Selection of
such third party shall be subject to the approval of the party whose records
are to be reviewed, such approval to be not unreasonably withheld. The results
of such a review as provided to the requesting party will consist solely of a
finding of compliance or non-compliance. The cost of such review shall be borne
by the requesting party and shall not be unreasonably burdensome for the party
whose records are to be reviewed.

GEN-PROBE and TEKNIKA each agree to include in all licenses which derive
benefits from this Non-Assertion Agreement provisions which permit review of
the Licensee's activities in like manner to the above to permit verification of
compliance by such Licensees with the provisions of Section 3.3.

          3.4 GEN-PROBE agrees not to assert against TEKNIKA, or TEKNIKA's
Affiliates or Licensees, in any jurisdiction the GEN-PROBE Patent Rights, or
any other patent rights which it now or hereafter owns or to which it now or
hereafter otherwise acquires rights that would be infringed by the practice of
the TEKNIKA Version or a Thermostable Version of transcription-based
amplification. The foregoing sentence however expressly shall not prevent or
prohibit GEN-PROBE from asserting any such Patent Rights, or such other patent
rights, to prevent TEKNIKA, or TEKNIKA's Affiliates or Licensees, from
practicing the GEN-PROBE Version of transcription-based amplification.

          3.5 TEKNIKA agrees not to assert against GEN-PROBE, or GEN-PROBE's
Affiliates or Licensees, in any jurisdiction the TEKNIKA Patent Rights, or any
other patent rights which it now or hereafter owns or to which it now or
hereafter otherwise acquires rights that would be infringed by the practice of
the GEN-PROBE Version or a Thermostable Version of transcription-based
amplification. The foregoing sentence however expressly shall not prevent or
prohibit TEKNIKA from asserting any such Patent Rights, or such other patent
rights, to prevent GEN-PROBE, or GEN-PROBE's Affiliates or Licensees, from
practicing the TEKNIKA Version of transcription-based amplification.

          3.6 GEN-PROBE agrees to allow Stanford University to convert
GEN-PROBE's license under the Stanford Agreement from an exclusive license to a
co-exclusive license, and to offer a license to TEKNIKA which shall carry with
it the right to grant sublicenses, provided that:

                                     [***]

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<PAGE>
[***]

Prior to concluding the aforementioned co-exclusive license between TEKNIKA and
STANFORD, the immunity under this Agreement shall be limited directly to
GEN-PROBE and TEKNIKA and shall not be available to any licensee of either party
until the aforementioned co-exclusive license between TEKNIKA and STANFORD is
concluded.

          3.7 GEN-PROBE and TEKNIKA each agree that the other party may grant
licenses to third parties under its own Patent Rights, provided that such
licenses include the limitations imposed by this Agreement, including, but not
limited to, Section 3.3. Any and all such licenses shall not carry with them
the right for such third party to grant licenses under either party's Patent
Rights to any other party.

          3.8 Warranty of Disclosure

TEKNIKA and GEN-PROBE each warrant that they have disclosed all rights to
patents and patent applications existing at the time of signature which relate
to transcription-based amplification or could block the practice of the other
party's Version or a Thermostable Version of transcription-based amplification
or claiming thermostable enzymes or their use, or transcription-based
amplification using such enzymes, which they own or have rights to, including
non-exclusive rights or access to, as through licensing, for example.

          3.9 [***]

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<PAGE>
[***]

Section 4.0. Termination of Legal Actions; Defense of Patent Rights

     4.1  Each party shall (i) promptly terminate any and all pending legal
actions and (ii) refrain from initiating any new legal actions concerning
transcription-based amplification which are directed against the other party's
Patent Rights or the Stanford Patent. Such legal actions include, but are not
limited to, actions in any patent office (e.g., oppositions and
re-examinations).

     4.2  Each party agrees to cooperate with the other party to the full
extent permissible by law and good legal practice in order to expeditiously
resolve any patent interference involving the parties with respect to claims
involving the Patent Rights or the Stanford Patent in accordance with the
provisions of Appendix C. The outcome of any interference involving Patent
Rights covering transcription-based amplification owned or licensed by
GEN-PROBE or TEKNIKA, or the Stanford Patent shall be subject to the terms of
this Agreement.

     4.3  Each party shall take any and all actions with respect to the
prosecution and defense of its Patent Rights that it deems appropriate,
(including defending its Patent Rights against infringers) and neither party
shall be responsible to the other party for any such actions that it may take,
or fail to take. Each party shall bear all costs associated with such actions
respecting its own Patent Rights.

     4.4  Either party may request that the other party provide non-financial
assistance in the prosecution and defense of its Patent Rights, and the other
party shall provide such assistance provided the provision of same shall not be
unreasonably burdensome in terms of time, costs and effort.

Section 5.0 Assignment

     5.1  A party shall not assign any of its rights and privileges under this
Agreement without the prior written consent of the other party, except to an
Affiliate or a successor in interest of all or substantially all the assets of
that part of the assigning party's business to which the Patent Rights relate,
which Affiliate or successor assumes in writing the performance of all the
terms and conditions of this Agreement to be performed by the assigning party.
After assignment to a non-Affiliate, the assigning party shall no longer be
immune hereunder. Any assignment shall not in any way affect the immunity,
referred to under Section 3.0 here above, of Licensees of the assigning party.

Section 6.0. Absence of Warranty or Representation

     6.1  Neither party warrants or represents that practicing or using any of
the transcription-based amplification processes which are the subject of this
Agreement does not infringe patents or other




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<PAGE>
intellectual property  rights of any third party, and no indemnity against such
infringement is provided by either party to the other. Each party acknowledges
and accepts such absence of warranty or representation from the other party.

Section 7.0. Confidentiality of Agreement Terms

     7.1 The parties hereto agree that they will not discuss the terms and
conditions of this Agreement, nor of any agreement between GEN-PROBE and
Stanford, nor of any agreement between TEKNIKA and Stanford, with any third
party (except as may be required by applicable law, regulation, or court order,
or in connection with the licensing of this transcription-based amplification
technology, but then to the least extent allowable and only on a general basis
without disclosure of financial terms and in any event subject to undertakings
of confidentiality) and they will not make any external public communications
with respect to this Agreement without consulting with and obtaining the prior
written approval of the other party. GEN-PROBE and TEKNIKA agree to include in
like manner in all license agreements with Licensees provisions to the same
effect.

Section 8.0. Future Discussions

     8.1 Each party confirms its willingness to enter into good faith
negotiations to attempt to reach mutual agreement on commercially reasonable
terms and conditions to license to the other party, on a non-exclusive basis,
its technologies or patents listed under Chapter II in Appendix B. Neither party
envisages granting exclusive licenses under Chapter II of Appendix B to a third
party. In the event, however, that either party wishes to initiate negotiations
that would grant an exclusive license to a third party for a patent or
technology listed under Chapter II in Appendix B, for a period of five (5) years
following the signing of this Agreement, such party will not do so without first
discussing with the other party the possibility of licensing to the other party
such patent or technology.

     8.2 The parties also confirm their willingness to discuss mutually
advantageous business arrangements with respect to additional technologies
useful in the framework of this Agreement, which are not included in Appendix A
or Appendix B, that they may develop, or acquire rights to, in the future.

Section 9.0. Joint Negotiations

9.1 TEKNIKA agrees to accept the co-exclusive license referred to in Section 3.6
above under the same terms and conditions as the Stanford Agreement, or on such
more favorable terms as may be negotiated with Stanford. Should Stanford be
unwilling or unable, within 90 days of the signing of this Agreement by both
parties, to offer such co-exclusive license to TEKNIKA on at least the same
terms and conditions as the Stanford Agreement, then either TEKNIKA or GEN-PROBE
may terminate this Agreement.

9.2 Notwithstanding the provisions of Section 7.0 of this Agreement, the parties
acknowledge that certain information concerning this Agreement may need to be
revealed to Stanford in order to convert Gen-Probe's license to a co-exclusive
license as set forth in Section 3.6 of this Agreement. The parties agree that
neither shall reveal any information about this Agreement to Stanford other than
the following, unless otherwise agreed by the parties in writing:
<PAGE>
(1)  GEN-PROBE and TEKNIKA have entered into a provisional non-assertion
agreement that will be finalized when Stanford has made license rights
available to TEKNIKA that are acceptable under the terms of the non-assertion
Agreement.

(2)  GEN-PROBE has agreed to allow Stanford to convert GEN-PROBE's license from
an exclusive license to a co-exclusive license, and to offer a license to
TEKNIKA which shall include the right to grant sublicenses, provided that:

        [***]

Section 10.    Termination of Agreement

        10.1   This Agreement shall expire on the expiration of the last to
expire Patent Right listed in Appendix A or the Stanford Patent.

        10.2   GEN-PROBE may terminate the obligations under Sections 3.1, 3.4
and 8 in cases in which TEKNIKA is in material breach, and TEKNIKA may terminate
the obligations under Sections 3.2, 3.5, and 8 in cases in which GEN-PROBE is in
material breach, of this Agreement upon or after the breach of any material
provision of this Agreement by the other party, if the other party has cured
such breach within ninety (90) days after written notice thereof by the
non-breaching party. Material breach shall be deemed to include, but not be
limited to, a breach of Sections 3.3, 3.4, 3.5, 3.6, 3.7, 3.9, 4, 5, 8, and 9.1
of this Agreement. Expiration or termination of this Agreement shall not relieve
the parties of any obligation accruing prior to such expiration or termination.

        10.3   Upon termination of this Agreement, as permitted by Section
10.2, the non-breaching party shall grant direct immunity from legal action to
Licensees of the breaching party, under the terms and conditions set forth in
this Agreement, provided that:

        (a) the non-breaching party shall have received express written notice
of the license granted to such Licensee prior to the effective termination date
of this Agreement;

        (b) the Licensee expressly agreed in writing on or before the ninetieth
(90th) day prior to the effective termination date of this Agreement to be
bound by the terms and conditions of this Agreement.

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Section 11. Governing Law

     11.1 This Agreement shall be construed, and its performance governed in
accordance with the laws of the State of New York, without regard to the
conflicts of law principles thereof, and, as applicable, the laws of the United
States of America.

Section 12. Arbitration

     12.1 Any dispute, controversy or claim originally initiated by either party
relating to, arising out of or resulting from this Agreement, or the performance
by either party of its obligations hereunder, whether before or after
termination of this Agreement, shall be finally resolved by binding arbitration.
Whenever a party shall decide to institute arbitration proceedings, it shall
have written notice to that effect to the other party. Any arbitration hereunder
shall be conducted under the Rules of Conciliation and Arbitration of the
International Chamber of Commerce. Each such arbitration shall be conducted in
the English language, by a panel of three arbitrators appointed in accordance
with such rules. Any such arbitration shall be held in New York, New York. The
arbitrators shall have the authority to grant specific performance, and to
allocate between the parties and costs of arbitration in such equitable manner
as they determine. Judgment upon the award so rendered may be entered in any
court having jurisdiction or application may be made to such court for judicial
acceptance of any award and an order of enforcement, as the case may be. In no
event shall a demand for arbitration be made after the date when institution of
a legal or equitable proceeding based upon such claim, dispute or other matter
in question would be barred by the applicable statute of limitations under
Section 11. For the avoidance of doubt, the provisions of this Section 12.1 do
not pertain to the arbitration referred to in Appendix C hereto.

Section 13. Entire Understanding

     13.1 This Agreement, and the Appendices A, B, C and D which form an
integral part thereof, embody the entire understanding between the parties and
supersede any prior representations, understandings and agreements between and
among them respecting the subject matter hereof. There are no representations,
agreements, arrangements or understandings, oral or written, between the parties
hereto relating to the subject matter of this Agreement which are not fully
expressed herein.

Section 14. Severability

     14.1 Any of the provisions of this Agreement which are determined to be
invalid or unenforceable in any jurisdiction shall be ineffective to the extent
of such invalidity or unenforceability in such jurisdiction, without rendering
invalid or unenforceable the remaining provisions hereof and without affecting
the validity or enforceability of any of the terms of this Agreement in any
other jurisdiction.
<PAGE>
Section 15. Notices

For TEKNIKA:

     Organon Teknika BV
     Boseind 15
     P.O. Box 84
     5280 AB Boxtel
     The Netherlands
     Attn. President

with copy to:

     Organon Teknika NV
     Veedijk 58
     2300 Turnhout
     Belgium
     Attn. President

For GEN-PROBE:

     Gen-Probe Incorporated
     9880 Campus Point Drive
     San Diego, CA 92121
     Attn. President and CEO

with copy to:

     Gen-Probe Incorporated
     9880 Campus Point Drive
     San Diego, CA 92121
     Atn. General Counsel

All notices required under this Agreement shall be delivered by hand, by United
States mail, or by courier, and a written receipt verifying the date and time
of delivery and to whom delivered shall be obtained by the sender. All such
notices will be deemed to have been delivered at such date and time.

<PAGE>
Either party may change the address for delivery of notices to it by providing
notice to the other party in the manner described.

IN WITNESS WHEREOF, the parties have executed this Agreement on the date first
set forth above.


GEN-PROBE INCORPORATED                       ORGANON TEKNIKA B.V.


By /s/Henry L. Nordhoff                      By /s/ Robert Salsmans
-------------------------                    -----------------------
Henry L. Nordhoff                            Dr. Robert Salsmans
Chairman, President and CEO                  President

                                             By /s/ A.J.F. Stap
                                             -----------------------
                                             A.J.F. Stap
[Approved Legal Stamp]                       Executive Vice President
                                             Corporate Development and
                                                Project Management

<PAGE>
                                   APPENDIX A

                            GEN-PROBE PATENT RIGHTS

<Table>
<Caption>

<S>                 <C>                 <C>                 <C>
                    PR DATE             PR APPL.            PUBL. NO.

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</Table>

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<PAGE>
                             APPENDIX A (continued)

                             TEKNIKA PATENT RIGHTS

<Table>
<Caption>

<S>                 <C>                 <C>                 <C>
                    PR DATE             PR APPL.            PUBL. NO.

[***]
</TABLE>

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                                   APPENDIX B

                                   CHAPTER II
                               GEN-PROBE PATENTS





                                     [***]








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<PAGE>
                             APPENDIX B (Continued)

                                   CHAPTER II
                               GEN-PROBE PATENTS

                                     [***]


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                             APPENDIX B (Continued)

                                TEKNIKA PATENTS

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                                   APPENDIX C

                           Determination of Priority

[***]

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                                   APPENDIX D
                                 ENZYME ASSAYS

[***]








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