<PAGE>
                                                                   EXHIBIT 10.11




















                            PATENT LICENSE AGREEMENT




















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                            PATENT LICENSE AGREEMENT

        This is a patent license agreement ("Agreement") made by and among Roche
Molecular Systems, Inc. ("RMS"), a Delaware corporation having an office at
Branchburg Township, 1080 U.S. Highway 202 Somerville, New Jersey 08876-3771,
and F. Hoffmann La Roche Ltd, a Switzerland limited liability company, with
offices at Grenzacherstrasse 124, CH-4002 Basel, Switzerland (both of which are
referred to herein as "ROCHE"), and Stratagene, a California corporation having
offices at 11099 N. Torrey Pines Road., La Jolla, California (referred to herein
as "SCS").

                                   BACKGROUND

A. ROCHE and its Affiliates own United States Patents Nos. 4,683,195, 4,683,202
and 4,965,188 and the corresponding foreign counterpart patents and patent
applications, describing and claiming gene amplification processes including,
inter alia, a process known as the polymerase chain reaction ("PCR") process.

B. ROCHE and its Affiliates also own United States Patent No. 4,889,818 and the
corresponding foreign counterpart patents and patent applications relating to
purified natural, as well as recombinant, themostable DNA polymerase isolated
from Thermus aquaticus ("nTaq" and "rTaq", respectively) as well as U.S. Patent
No. 5,079,352 and the corresponding foreign counterpart patents and patent
applications relating to rTaq and fragments thereof.

C. ROCHE and its Affiliates also own United States Patent No. 5,075,216 and the
corresponding foreign counterpart patents and patent applications relating to
sequencing with Taq DNA polymerase.



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<PAGE>

D. Roche and its Affiliates also own USSN 07/387,003 and the corresponding
foreign counterpart patent applications relating to stabilized enzyme
compositions.

E. The patent rights referred to above were previously owned by Cetus
Corporation ("Cetus"), a Delaware corporation having an office in Emeryville,
California.

F. The Perkin-Elmer Corporation ("P-E") has exclusive rights under the patent
rights referred to above in certain fields, including the field of research,
pursuant to an agreement dated December 11, 1991 with ROCHE and has certain
rights to grant sublicenses in said fields. Under separate agreements between
ROCHE and P-E and in consideration of a share of royalties due hereunder, P-E
has released ROCHE from such of P-E's rights in the aforementioned fields as is
necessary for ROCHE to convey to SCS the rights and licenses specified in this
Agreement.

G. On July 1, 1990, Cetus entered into a "Patent License Agreement"
(hereinafter, "the 1990 Agreement") with SCS granting SCS rights to manufacture,
use and sell purified natural DNA polymerase reagents isolated from Thermus
aquaticus, ("nTaq"), for non-PCR uses, on the condition that SCS "refrain from
promoting the use of" such reagents in "PCR Applications" (which is defined on
page 3 of the 1990 Agreement).

H. SCS has manufactured and sold Taq DNA polymerase under the license under the
1990 Agreement above, and wishes to expand its rights to include the right to
make, use and sell to the research and to other markets Taq DNA polymerase and
other products covered by AMPLIFICATION PATENT RIGHTS and/or SEQUENCING PATENT
RIGHTS, as hereinafter defined. To this end, Stratagene is willing to terminate
the 1990 Agreement and to enter into this Agreement.



                                       2
<PAGE>

I. In structuring the present Agreement, the parties have considered the
possibility that novel polymerases may be developed by SCS (and others) that
are useful in AMPLIFICATION PATENT RIGHTS and that, without a license from
ROCHE, SCS may not pass on to its customers the right to use said polymerases in
AMPLIFICATION PATENT RIGHTS. It is SCS' desire to promote and sell such
internally developed, or licensed or purchased polymerases and/or kits
incorporating such polymerases for use in AMPLIFICATION PATENT RIGHTS and to
pass on to the purchaser such a license and ROCHE is willing to permit SCS to do
so.

J. In addition, the parties take note that SCS may, in its discretion, market
the products licensed hereunder in conjunction with other products, components
or materials, both separately or together, and in various package arrangements,
which may be useful in ROCHE's AMPLIFICATION PATENT RIGHTS. Taking this into
consideration, for the mutual convenience of the parties, the products on which
SCS will pay a royalty, that is the royalty base, will include those products as
specifically described below that are adapted for, promoted or supported for use
with the patent rights licensed herein. Furthermore, in an effort to minimize
customer confusion as to which SCS products in fact permit the customer to
practice AMPLIFICATION PATENT RIGHTS without additional licenses, SCS agrees, as
is further described below, to give special consideration to the manner in which
it promotes and sells its other products which may be useful in AMPLIFICATION
PATENT RIGHTS but which are not specifically licensed by ROCHE for that purpose.

        NOW, THEREFORE, for and in consideration of the mutual covenants
contained herein, ROCHE and SCS hereby agree as follows:



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<PAGE>

1. DEFINITIONS

        For the purpose of this Agreement, and solely for that purpose, the
terms set forth hereinafter shall be defined as follows:

        1.1 The term "AFFILIATE" of a designated party to this Agreement shall
mean:

                a)      an organization of which fifty percent (50%) or more of
                        the voting stock is controlled or owned directly or
                        indirectly by either party to this Agreement;

                b)      an organization which directly or indirectly owns or
                        controls fifty percent (50%) or more of the voting stock
                        of either party to this Agreement;

                c)      an organization, the majority ownership of which is
                        directly or indirectly common to the majority ownership
                        of either party to this Agreement; and

                d)      an organization under (a), (b), or (c) above in which
                        the amount of said ownership is less than fifty percent
                        (50%) and that amount is the maximum amount permitted
                        pursuant to the law governing the ownership of said
                        organization.



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<PAGE>

It is understood and agreed, however, that the term "Affiliate" shall not
include Genentech Inc., a company located at 460 Point San Bruno Boulevard,
South San Francisco, California, U.S.A. ("Genentech").

        1.2 "AMPLIFICATION PATENT RIGHTS" shall mean the nucleic acid
amplification processes covered by United States Patent Nos. 4,683,195,
4,683,202 and 4,965,188, and those claims in foreign patents and patent
applications which correspond to issued claims in the above patents and which
foreign patents and patent applications claim priority from the patent
applications on which the above patents are based, and access to which patents
and patent applications are necessary for SCS to manufacture, use and sell Taq
Reagents and SCS Enzymes in accordance with the rights granted in sections
2.2-2.5 hereto.

        1.3 "APPLICATION FIELDS" shall mean those fields listed in Appendix A
which SCS has elected to include in this Agreement as specified in Section 5.

        1.4 "APPLICATION KIT" shall mean a Licensed Product in combination with
such other reagents, enzymes or other materials as are necessary to perform a
PCR-based assay or nucleic: acid sequencing in the APPLICATION FIELD for which
it is sold.

        1.5 "AUTHORIZED THERMAL CYCLER" shall mean a thermal cycler or
temperature cycling instrument suitable for the automated practice of the PCR
Process for which a fee has been paid to P-E for authorization in the LICENSED
FIELDS under AMPLIFICATION PATENT RIGHTS. All P-E Thermal Cyclers are AUTHORIZED
THERMAL CYCLERS.



                                       5
<PAGE>

        1.6 "SCS ENZYME" shall mean any thermostable polymerase that is not
derived from Thermus aquaricus and that is not within TAQ PATENT RIGHTS,
developed, purchased, or licensed by SCS from a third party, which enzyme may be
used in or with the PCR PROCESS. An enzyme shall not be included in this
definition if SCS demonstrates to ROCHE's satisfaction that said enzyme is in
fact used predominantly for other than AMPLIFICATION PATENT RIGHTS. For example,
an enzyme that is marketed in a formulation that renders the enzyme unsuitable
for, or is otherwise chemically or structurally rendered unsuitable for, use in
PCR will reasonably be considered not to be an SCS Enzyme unless ROCHE or SCS
becomes aware that said enzyme is in fact used predominantly in PCR. Unless
excluded as provided herein, all sales of said SCS ENZYMES are assumed to be for
use in AMPLIFICATION PATENT RIGHTS.

        1.7 "EFFECTIVE DATE" shall mean July 1, 1994.

        1.8 "LICENSED APPLICATION PRODUCT" shall mean (a) an APPLICATION KIT or
(b) reagents, components or other materials which are sold in connection with
the sale of an APPLICATION KIT by SCS and which are adapted for or promoted or
supported for use by customers in PCR TESTING or nucleic acid sequencing in
APPLICATION FIELDS. As used herein, "PCR TESTING" shall include all steps in the
analysis of a sample for the presence or absence of amplifiable nucleic acid
from preparation of the sample to detection and/or analysis of any amplified
product

        1.9 "LICENSED FIELDS" shall mean the RESEARCH FIELD and the APPLICATION
FIELDS.



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<PAGE>

        1.10 "LICENSED PRODUCT" shall mean:

                a)      a TAQ REAGENT or SCS ENZYME used or sold in a country
                        where the use or sale of such TAQ REAGENT or SCS ENZYME
                        would infringe at least one VALID CLAIM within
                        AMPLIFICATION PATENT RIGHTS or SEQUENCING PATENT
                        RIGHTS; and/or

                b)      a TAQ REAGENT or SCS ENZYME made, used or sold in a
                        country where the manufacture, use or sale thereof would
                        infringe a VALID CLAIM within TAQ PATENT RIGHTS.

        1.11 "LICENSED RESEARCH PRODUCTS" shall mean any product including but
not limited to kits, which products consist of or contain a LICENSED PRODUCT and
may include all or some of the following components: buffers, nucleotides,
enzymes, or other reagents or materials. Notwithstanding the foregoing, it is
understood and agreed that such LICENSED RESEARCH PRODUCT shall not contain,
without ROCHE's specific approval, which approval shall be strictly
discretionary with ROCHE, nucleic acid sequences homologous to the nucleic acid
sequences of any human infectious agent or pathogen.

        1.12 "NET SALES" shall mean the gross invoice amount less

                (i)     credits, freight and insurance and other discounts
                        allowed and taken, in amounts customary in the trade,
                        and

                (ii)    sales and/or use taxes and/or duties for particular
                        sales.



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<PAGE>

        No allowance or deduction shall be made for commissions or collections,
by whatever name known.

        NET SALES shall be calculated on the basis of sales or transfers to end
users by SCS or its Affiliate or distributor. In the event SCS is unable to
account for sales to third party end users by its distributors, the NET SALES
shall be calculated as the sales price to such distributors multiplied by ***,
which factor represents a ***% margin allowed to the distributor. Sales to a
third party controlling, controlled by, or under common control with SCS, or
enjoying a special course of dealing, shall be determined by reference to the
listed or published price for the product sold or transferred which would be
applicable in an arm's length transaction with an unrelated third party.

        1.13 "PCR PROCESS" shall mean the polymerase chain reaction (PCR)
process, which is one of the amplification processes identified in AMPLIFICATION
PATENT RIGHTS.

        1.14 "RESEARCH FIELD" shall mean the internal use by an end user of a
product solely in applications of the end user (or in applications of the end
user's customer, if the end user is performing contract research) in scientific
research and development which, by way of example but not by way of limitation,
expressly excludes:

                a)      reportable results generated from clinical applications
                        in humans or animals such as the detection or
                        measurement, treatment, prevention or mitigation of
                        disease or other health-related condition; the detection
                        of pathogens, detection of




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                        genetic disease or genetic pre-disposition to disease;
                        tissue transplantation typing; and parentage testing;

                b)      the use of PCR to manufacture any products for sale;

                c)      the commercial application of Taggants, which shall be
                        defined herein to be the application of PCR PROCESS or
                        AMPLIFICATION PATENT RIGHTS to identify any synthetic
                        nucleotide sequence which has been inserted, dispersed
                        or applied into a product, substance or organism in
                        order to identify such product, substance or organism or
                        to convey other specific information.

                d)      Forensic Applications (as defined in Appendix A);


                e)      human identification testing, and parentage
                        determination;


                f)      Plant Diagnostics (as defined in Appendix A);

                g)      Animal Diagnostics, Animal Identity Testing and Positive
                        Trait Breeding (as defined in Appendix A);

                h)      quality assurance and quality control, including without
                        limitation, conformance with specifications, purity, and
                        batch-to-batch consistency if performed for third
                        parties on a commercial basis; and



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<PAGE>

                i)      Environmental Testing (as defined in Appendix A);

        1.15 "SEQUENCING PATENT RIGHTS" shall mean the claims of United States
Patent No. 5,075,216 and those claims in foreign patents and parent applications
which correspond to issued claims in the above patent and which foreign patents
and patent applications claim priority from the patent application(s) on which
the '216 patent is based, and access to which patents and patent applications
are necessary for SCS to manufacture, use and sell TAQ REAGENTS pursuant to
Section 2.5 hereto.

        1.16 "TAQ PATENT RIGHTS" shall mean those claims of United States Patent
Nos. 4,889,818 and 5,079,352 and U.S.S.N. 07/387,003, and any reissues and
continuations thereof, and those claims in foreign patents and patent
applications claiming priority from a patent application which is a basis for
any of the above US patents or patent applications and which foreign claims
include within their scope a TAQ REAGENT but only to the extent that such claims
are necessary for SCS to manufacture, use and sell TAQ REAGENTS pursuant to
sections 2.2-2.5 hereto, except that dim rights specifically exclude the
"Stoffel Fragment" (Perkin-Elmer catalogue #N808-0038) and the "Abramson Mutant"
(an amino acid replacement of glycine corresponding to position 46 of the Taq
polymerase amino acid sequence provided in Lawyer et. al. 1989 (JBC 264:
6247-6437).

        1.17 "TAQ REAGENT" shall mean an enzyme the manufacture, use or sale of
which would be covered by at least one VALID CLAIM within TAQ PATENT RIGHTS.

        1.18 "TERRITORY" shall mean worldwide.



                                       10
<PAGE>

        1.19 "UNITS" of thermostable polymerase shall be defined by equivalence
to units of AmpliTaq DNA polymerase as described in Appendix B.

        1.20 "VALID CLAIM" shall mean the claim of a patent or pending patent
application which has not otherwise been held invalid or unenforceable by a
court from which no appeal has or can be taken, or has not otherwise finally
been held unpatentable by the appropriate administrative agency.

        2. GRANT TO SCS

        2.1 Termination of the Cetus/SCS 1900 Agreement. In consideration of
the rights granted herein to SCS by ROCHE and SCS' obligation to pay royalties,
SCS and ROCHE hereby agree that their respective rights in and obligations under
the 1990 Agreement between Cetus and SCS are terminated, and the terms thereof
superseded by the present Agreement as of the EFFECTIVE DATE hereof, except that
all royalties due under the 1990 Agreement as of the EFFECTIVE DATE of the
present Agreement, shall be paid to ROCHE in accordance with the terms and
schedule of the 1990 Agreement.

        2.2 Licenses Under TAQ PATENT RIGHTS. Upon the terms and subject to the
conditions of this Agreement, ROCHE hereby grants to SCS and its AFFILIATES and
SCS hereby accepts from ROCHE, for itself and its AFFILIATES, a non-exclusive,
royalty bearing license in the TERRITORY, without the right to sublicense, under
TAQ PATENT RIGHTS, to: (i) manufacture (but not to have manufactured) in the
TERRITORY (but excluding Japan); (ii) to use TAQ REAGENTS in the TERRITORY; and
(iii) to sell in the TERRITORY as follows and for no other purpose:


                                       11
<PAGE>

        a) to customers in the RESEARCH FIELD for such customers' own internal
           use in the RESEARCH FIELD only;

        b) to customers in the APPLICATION FIELDS, which customers are those
           licensed by other than a product label license under AMPLIFICATION
           PATENT RIGHTS in such APPLICATION FIELDS for such customer's own
           internal use in performing the PCR PROCESS in such APPLICATION
           FIELDS;

        c) for incorporation in APPLICATION KITS pursuant to Section 2.4.

        2.3 License to Promote and Sell for PCR in the RESEARCH FIELD. In
consideration of SCS' payment of royalties on sales of LICENSED RESEARCH
PRODUCTS, ROCHE hereby grants to SCS and its AFFILIATES and SCS accepts from
ROCHE for itself and its AFFILIATES, a limited, non-exclusive license in the
TERRITORY under the AMPLIFICATION PATENT RIGHTS to promote and sell LICENSED
RESEARCH PRODUCTS in the RESEARCH FIELD and to pass on with such sales of
Licensed Research Products to end user purchasers only so much of those
AMPLIFICATION PATENT RIGHTS as are necessary to be consistent with the label
licenses accompanying those products, and as are necessary for such purchasers
to use such LICENSED RESEARCH PRODUCTS in or with the PCR PROCESS either in an
AUTHORIZED THERMAL CYCLER, strictly for such purchasers' own use in the RESEARCH
FIELD.

        2.4 License to Promote and Sell for PCR in APPLICATION FIELDS. In
further consideration of SCS' payment of royalties on sales of LICENSED
APPLICATION PRODUCTS, ROCHE hereby grants to SCS and its AFFILIATES and SCS
accepts from ROCHE for itself and its AFFILIATES, a limited, non-exclusive
license in the TERRITORY under the AMPLIFICATION


                                       12
<PAGE>

PATENT RIGHTS to promote and sell APPLICATION KITS in the APPLICATION FIELDS and
to pass on with such sales of APPLICATION KITS to end user purchasers only so
much of those AMPLIFICATION PATENT RIGHTS as are necessary to be consistent with
the label licenses accompanying those APPLICATION KITS, and as are necessary for
such purchasers' own internal use of such APPLICATION KITS in the APPLICATION
FIELDS for which the APPLICATION KITS are sold, said use being restricted to be
in conjunction with an AUTHORIZED THERMAL CYCLER.

        2.5 License to Promote and Sell for Sequencing in the RESEARCH FIELD and
APPLICATION FIELDS. In further consideration of SCS' payment of royalties on
sales of LICENSED RESEARCH PRODUCTS and LICENSED APPLICATION PRODUCTS, ROCHE
hereby grants to SCS and its AFFILIATES and SCS accepts from ROCHE for itself
and its AFFILIATES, a limited, non-exclusive license in the TERRITORY under the
SEQUENCING PATENT RIGHTS to sell LICENSED RESEARCH PRODUCTS in the RESEARCH
FIELD and APPLICATION KITS in the APPLICATION FIELDS and to pass with such sales
to end user purchasers only so much of those SEQUENCING PATENT RIGHTS as are
necessary for such purchaser's own internal use of such LICENSED RESEARCH
PRODUCTS or APPLICATION KITS in sequencing in the RESEARCH FIELD and the
APPLICATION FIELDS.

        2.6 SCS expressly acknowledges and agrees that the licenses granted
pursuant to this Agreement are personal to SCS and its AFFILIATES alone, and SCS
and its AFFILIATES shall have no right to sublicense, assign or otherwise
transfer or share its rights under the foregoing licenses, except that SCS and
its Affiliates may sell or distribute LICENSED RESEARCH PRODUCTS and LICENSED
APPLICATION PRODUCTS through distributors.


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<PAGE>

        2.7 Except as is specifically provided herein, this Agreement shall not
limit the rights of ROCHE in any way. It is specifically understood that as
between the parties to this Agreement, ROCHE reserves the right itself or
through its AFFILIATES to practice under TAQ PATENT RIGHTS, SEQUENCING PATENT
RIGHTS and AMPLIFICATION PATENT RIGHTS, including the PCR PROCESS itself, and,
subject to the provisions of Section 12 herein, to sublicense, assign or
otherwise transfer the TAQ PATENT RIGHTS and AMPLIFICATION PATENT RIGHTS and
SEQUENCING PATENT RIGHTS to others for any purpose whatsoever.

        2.8 SCS and its AFFILIATES shall affix to each particular LICENSED
RESEARCH PRODUCT or LICENSED APPLICATION PRODUCT licensed hereunder, either on a
product insert accompanying the product or on the product itself, one of the
labels set forth in Appendix C, as ROCHE shall direct, or such other label as
ROCHE may direct from time to time. Such changes in labelling shall be subject
to the approval of SCS, which shall not be unreasonably withheld. As to the
labels set forth in Appendix C, SCS understands and agrees that the notices
numbered 1 through 5 reflect ROCHE's present label licensing policy and shall be
used on the labels for SCS products as appropriate. In regard to these or any
other changes in labels directed by RMS, SCS shall have a reasonable time period
over which to change its labels.

        2.9 SCS hereby covenants that it and its AFFILIATES shall sell, market
and otherwise promote products licensed hereunder only for use in accordance
with the terms of this Agreement and they shall use their best efforts, as
described herein, and shall contractually require all of its distributors to
also use their best efforts, as described herein, to ensure that these products
are used in compliance with the letter and intent of this Agreement. To that
end, SCS, its AFFILIATES and distributors shall prominently display in
catalogues and brochures describing LICENSED RESEARCH PRODUCTS and/or LICENSED


                                       14
<PAGE>

APPLICATION PRODUCTS, the label license statements as referred to in Section 2.8
and set forth in Appendix C. Furthermore, in advertisements or any other
materials intended for distribution to third parties and referring in any way to
products licensed hereunder and the use of said products in the PCR PROCESS, but
in which it is not practical to include the complete label license statements,
SCS will include a comparable restriction on use as follows:

        Purchase of this product (or product name] is accompanied by a license
        to use it in the Polymerase Chain Reaction (PCR) process in conjunction
        with an Authorized Thermal Cycler.

or other statement approved in writing by ROCHE.

        2.10 a) SCS acknowledges that sales to third parties not in compliance
with the field and use restrictions pursuant to Sections 2.2 - 2.5 constitute an
activity outside the scope of the licenses granted under this Agreement which is
detrimental to ROCHE, its AFFILIATES and distributors. SCS therefore agrees that
once it is notified by ROCHE or once it independently has actual knowledge of
that a particular purchaser is using or intends to use any product licensed
herein other than as is specifically provided in this Agreement, SCS shall
promptly notify said purchaser in writing that such use is unlicensed and that a
license for said use must be obtained from ROCHE or P-E. SCS shall also require
its AFFILIATES and distributors to report to SCS any unlicensed activities of
which they become aware. SCS further agrees that continued or resumed sales by
SCS, its AFFILIATES; or a distributor, to a particular purchaser of which SCS
was previously notified or is otherwise aware is using any licensed product in a
manner other than as expressly provided in this Agreement, shall constitute a
breach under Section 6.5 of the Agreement A written certification by a
distributor or purchaser which is executed by an officer of said distributor


                                       15
<PAGE>

or purchaser which officer may legally bind the company, that it has ceased the
unlicensed activity, or a written certification by SCS which is executed by an
officer of SCS which officer may legally bind SCS that it has ceased sales to
such distributor or purchaser, shall be a cure under Section 6.5.

        b) Pursuant to the foregoing general requirements, SCS shall, when it
           receives an order for a LICENSED PRODUCT from any customer, which SCS
           recognizes as significantly exceeding that customer's typical usage
           requirements, contact the customer and specifically inform the
           customer that the sale of such LICENSED PRODUCT is limited for use by
           the customer for internal testing only. Said customers shall be
           required to furnish a written certification that customer intends to
           use said LICENSED PRODUCT in accordance with the licenses enumerated
           in Sections 2.2 - 2.5 hereto.

        c) Further pursuant to the general provisions of Section (a) above, SCS
           and its AFFILIATES understand and agree that the only customers to
           whom they may sell TAQ REAGENTS and SCS ENZYMES pursuant to Section
           2.2 (b) are those licensed under AMPLIFICATION PATENT RIGHTS by ROCHE
           or P-E by other than a product label license.

        d) SCS agrees that it shall provide to ROCHE a copy of each of its
           notices to purchasers/distributors pursuant to this section, as well
           as a copy of each certification of compliance by
           purchasers/distributor's in the event such certification is required
           under the provisions of this Agreement.

        e) The parties understand and hereby agree that SCS shall have no
           obligation to monitor or police the use of AUTHORIZED THERMAL CYCLERS
           or by SCS' customers, and that SCS' obligations hereinunder in regard
           to AUTHORIZED THERMAL CYCLERS


                                       16
<PAGE>
shall be limited to providing the label license referred to in Section 2.8 and
set forth in Appendix C. However, SCS agrees not to knowingly promote the use of
thermal cyclers that are not authorized for use in PCR or under AMPLIFICATION
PATENT RIGHTS and further agrees not to provide sales, marketing, or technical
literature regarding the use of SCS ENZYMES or TAQ REAGENTS under PATENT RIGHTS
specifically with thermal cyclers that are not authorized.

        ROCHE hereby agrees that ROCHE will enforce its rights and will use its
best efforts to cause P-E to enforce its rights with regard to customers of SCS
not using AUTHORIZED THERMAL CYCLERS in the same manner and to the same extent
ROCHE and P-E treat their own customers in the same circumstances.

        2.11 Roche hereby grants to SCS and its Affiliates the right and SCS
accepts for itself and its Affiliates and agrees to credit ROCHE as the source
of patent rights in SCS' promotional materials, including for example
advertisements, product inserts and data sheets, intended for distribution to
third parties as follows:

        This product is sold under licensing arrangements with Roche Molecular
        Systems, Inc., F. Hoffmann-La Roche Ltd, and The Perkin-Elmer
        Corporation."

Such reference will be reasonably prominent and in materials (for example,
catalogues) containing multiple product descriptions, will be directly
associated with information on each specific product covered by this Agreement.

        3. GRANT TO ROCHE


        If SCS elects to *** or elects to ***, SCS shall give ROCHE a first
option to negotiate for a



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                                       17
<PAGE>


period of *** a non-exclusive license to manufacture and sell directly or
through distributors, such ***. The terms of said licenses shall be negotiated
in good faith by the parties, taking into consideration the relevant market
factors typically considered in such agreements, but any negotiated royalty
shall not exceed ***% of the Net Selling Price of ROCHE to its customers or
distributors.  The term of said license shall be commensurate with the terms of
the last to expire of any patent covering ROCHE's customers' use of such enzyme
without further payment of any kind from end user customers to SCS or its
licensor, if any. If ROCHE does not exercise the option hereunder, ROCHE shall
nonetheless be entitled to a non-exclusive license to make, use or sell said ***
under the same terms and conditions as the most favorable license terms granted
by SCS.



        4. ROYALTIES, RECORDS AND REPORTS

        4.1 Royalties. For the rights and privileges granted under this
Agreement, SCS shall pay royalties on products licensed hereunder which are used
by SCS or its AFFILIATES or sold, distributed, or otherwise transferred by SCS
or its AFFILIATES (with or without payment), as follows below, except as
otherwise specifically modified by Section 5.2 and Appendix A.

        a) *** per Unit for TAQ REAGENTS;

        b) for LICENSED RESEARCH PRODUCTS AND LICENSED APPLICATION PRODUCTS that
           include TAQ REAGENTS, ***% of the Net Sales of each LICENSED RESEARCH
           PRODUCT and LICENSED APPLICATION PRODUCT or *** per unit of TAQ
           REAGENTS in such LICENSED


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                                       18
<PAGE>

           RESEARCH PRODUCT or LICENSED APPLICATION PRODUCT, whichever is
           higher;

        c) for SCS ENZYMES, the dollars per unit calculated by multiplying ***
           by the PCR Effectiveness Ratio of the SCS ENZYME to AmpliTaq
           DNA Polymerase in the assay described in Appendix B;

        d) for LICENSED RESEARCH PRODUCTS and LICENSED APPLICATION PRODUCTS that
           include SCS ENZYMES, ***% of the Net Sales of the LICENSED RESEARCH
           PRODUCT or LICENSED APPLICATION PRODUCT or the dollar amount for the
           SCS ENZYME in the LICENSED RESEARCH PRODUCT or LICENSED APPLICATION
           PRODUCT calculated pursuant to c) above, whichever is larger;

        e) for LICENSED APPLICATION PRODUCTS which contain neither TAQ REAGENTS
           nor SCS ENZYMES, ***% of the NET SALES of the LICENSED APPLICATION
           PRODUCT; and

        f) for combinations of TAQ REAGENTS and SCS ENZYMES, and for LICENSED
           RESEARCH PRODUCTS and LICENSED APPLICATION PRODUCTS containing a
           combination of TAQ REAGENTS and SCS ENZYMES, an amount calculated by
           a combination of a) and c) or b) and d), as the case may be.


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                                       19
<PAGE>

        4.2 SCS and its AFFILIATES shall keep full, true and accurate books of
account containing all particulars which may be necessary for the purpose of
showing the amount payable by way of royalty or by way of any other provision
under this Agreement. Such books and the supporting data shall be available for
inspection during reasonable business hours, and upon reasonable written notice
to SCS, for three (3) years following the end of the calendar year to which they
pertain by an independent certified public accountant retained by ROCHE for the
purpose of verifying the accuracy of SCS' royalty statements or SCS' compliance
in other respects with this Agreement. If in dispute, such records shall be kept
until the dispute is settled. The inspection of records shall be at ROCHE's sole
cost unless the inspector concludes that royalties reported by SCS for the
period being audited are understated by five percent (5%) or more from actual
royalties, in which case the costs and expenses of such inspection shall be paid
by SCS.

        4.3 SCS shall within thirty (30) days after the first day of January,
April, July and October of each year deliver to the addresses provided below a
true and accurate royalty report. This report shall be in accordance with the
royalty report form attached hereto as Appendix D. This report shall be on a
country-by-country basis and shall give such particulars of the business
conducted by SCS in each country during the preceding three (3) calendar months
as are pertinent to an accounting for royalty under this Agreement and shall
include at least the following:

                (i) separately itemized quantities of products licensed
                    hereunder that are used, sold or otherwise transferred by
                    SCS during those three (3) months;




                                       20
<PAGE>
                  (ii)     THE UNITS of TAQ REAGENTS or SCS ENZYMES each product
                           licensed hereunder as determined by the assay
                           described in Appendix B;

                  (iii)    the NET SALES of each LICENSED RESEARCH PRODUCT and
                           LICENSED APPLICATION PRODUCT;

                  (iv)     the calculation of net royalties based on a royalty
                           rate of *** per unit;

                  (v)      the credit applicable to net royalties pursuant to
                           Section 4.5;

                  (vi)     the net royalties due. If no royalties are due, it
                           shall be so reported.

                  The correctness and completeness of each such report shall be
attested to in writing by the responsible financial officer of SCS' organization
or by SCS' external auditor or by the chairman or other head of SCS' internal
audit committee.

                  Simultaneously with the delivery of each such royalty report,
SCS shall pay to P-E the royalty and any other payments due under this Agreement
for the period covered by such report. All amounts payable hereunder by SCS
shall be payable in United


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                                       21
<PAGE>


States currency and sent by the due date, together with the royalty report, to
the following address:

                    Applied Biosystems Division
                    The Perkin-Elmer Corporation
                    850 Lincoln Centre Drive
                    Foster City, CA. 94404
                    Attn: Licensing Manager

or to such other address as P-E may designate. A copy of the royalty report
shall also be sent to:

                    Roche Molecular Systems, Inc.
                    1145 Atlantic Avenue, Suite 100
                    Alameda, California 94501
                    Attn: Licensing Manager

or to such other address as ROCHE may designate.


         4.4 If SCS shall fail to pay any amount specified under this Agreement
after the due date thereof, the amount owed shall bear interest at the Citibank,
NA base, lending rate ("Prime Rate") plus 3% from the due date until paid,
provided, however, that if this interest rate is held to be unenforceable for
any reason, the interest rate shall be the maximum rate allowed by law at the
time the payment is due.

         4.5 a) The parties agree that the royalty rates and unit fees set forth
in Section 4.1 are reasonable in view of the proprietary rights associated with
the products licensed hereunder and the consequent relative importance of these
products in the marketplace. The parties also recognize, however, that a
substantive change might occur in the marketplace, including, for example, a
change in ROCHE's proprietary position, or in the status of technological
alternatives that are non-proprietary to ROCHE, which change


                                       22
<PAGE>

in the marketplace might significantly detract from the value added of the
products licensed hereunder and thereby, in light of the royalty schedule of
Section 4.1 potentially makes SCS' marketing position correspondingly less
competitive. In the event of any such change in the marketplace, the parties
agree to discuss whether adjustments to the financial terms herein would be
appropriate and otherwise acceptable to ROCHE.


(b) In an effort to assist SCS in remaining competitive in light of such changes
in the marketplace, the parties have specifically agreed that the following
mechanism shall be available to provide SCS royalty relief: if ROCHE ascertains
that P-E's worldwide combined "Average Transaction Price" ("ATP") *** in a ***
period (as is provided below) is less than *** per unit, then SCS' unit royalty
for *** for that same *** period shall be *** per unit multiplied by the
fraction ***, but in no event shall SCS' unit royalty be reduced below *** per
unit for *** nor raised above *** per unit. Such ATP calculations shall be made
by ROCHE *** for the *** period *** each *** and SCS shall be notified before
the next scheduled royalty payment if it is entitled to a credit for the
previously reported *** period. By way of example as to how said royalty
adjustments will operate, on the *** after the effective date of this agreement
and every *** thereafter, ROCHE shall ascertain *** for the preceding *** (or in
the case of the first such calculation, whichever time period falls between the
Effective Date and the next ***) and shall calculate the per-unit royalty as
above described. If that unit royalty is other than *** per unit, ROCHE shall so
notify SCS before SCS' next scheduled royalty payment, so that SCS may take the
appropriate credit against the royalties next owed.


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                                       23

<PAGE>


                  As used herein. "Average Transaction Price" shall mean the
average transfer price par unit for all *** transferred by P-E or its Affiliates
to end users (which, in P-E's case shall mean to other than Roche or Roche's
Affiliates). "Average Transaction Price" shall be calculated by dividing the
worldwide aggregate NET SALES of all products transferred by P-E that contain
only *** by the worldwide aggregate UNITS of *** contained in those products.

         Except as is specifically provided by the mechanism to provide royalty
relief described in this Section 4.5 (b) above, ROCHE shall be under no
obligation to change or renegotiate any sections, provisions or terms of this
Agreement.

         5.       LICENSE IN ADDITIONAL FIELDS

                  5.1 SCS may elect at the time of execution of this agreement,
or shall maintain an option, exercisable for five years from the EFFECTIVE DATE
of this Agreement, to obtain additional license rights in the LICENSED FIELDS.

                  5.2 Appendix A specifies for each field to which this option
applies a license issuance fee, where applicable, and the applicable royalty
rate if such rate is different from that specified in Section 4.1, for each such
field. Roche shall have the right to change said license issuance fees and
royalty rate after *** from the EFFECTIVE DATE of this Agreement for any field
which has not become a LICENSED FIELD pursuant to Section 5.4.


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                                       24
<PAGE>


                  5.3 if not elected at the time of execution of this Agreement,
SCS may exercise its option to obtain a license for each such additional field
by giving ROCHE 60 days' written notice at any time during the option period.

                  5.4 Each individual field in addition to RESEARCH FIELD will
become a LICENSED FIELD when the specified license issuance fee has been paid.

         6.       TERM; TERMINATION

                  6.1 The license granted to SCS herein and SCS' obligations to
pay royalties hereunder, shall commence on the EFFECTIVE DATE and terminate on
the expiration of the last to expire of the patents within AMPLIFICATION PATENT
RIGHTS, SEQUENCING PATENT RIGHTS and TAQ PATENT RIGHTS to the extent a license
of right under any of the foregoing surviving Patent Rights is being exercised
pursuant to sections 2.2-2.5 hereto.

                  6.2 Notwithstanding any other Section of this Agreement, SCS
may terminate this agreement for any reason on ninety (90) days' written notice
to ROCHE. If SCS elects to terminate this Agreement pursuant to this section, it
shall within thirty (30) days of said termination, notify each of its customers
that SCS is no longer licensed under AMPLIFICATION PATENT RIGHTS, TAQ PATENT
RIGHTS, or SEQUENCING PATENT RIGHTS.

                  6.3 Notwithstanding any other section of this Agreement, ROCHE
may terminate this Agreement, effective immediately upon notice of termination
to SCS, in the event that a third party which is licensed by ROCHE to
manufacture products for use in PCR-based human diagnostic testing acquires
directly or indirectly 50% or more of the voting stock of SCS.


                                       25
<PAGE>


                  6.4 The license granted hereunder to SCS shall automatically
terminate upon (i) an adjudication of SCS as bankrupt or insolvent, or SCS'
admission in writing of its inability to pay its obligations as they mature; or
(ii) an assignment by SCS for the benefit of creditors; or (iii) SCS' applying
for or consenting to the appointment of a receiver, trustee or similar officer
for any substantial part of its property or such receiver, trustee or similar
officers appointment without the application or consent of SCS, if such
appointment shall continue undischarged for a period of ninety (90) days; or
(iv) SCS' instituting (by petition, application, answer, consent or otherwise)
any bankruptcy, insolvency arrangement, or similar proceeding relating to SCS
under the laws of any jurisdiction; or (v) the institution of any such
proceeding (by petition, application or otherwise) against SCS, if such
proceeding shall remain undismissed for a period of ninety (90) days or the
issuance or levy of any judgment, writ, warrant of attachment or execution or
similar process against a substantial part of the property of SCS, if such
judgment, writ, or similar process shall not be released, vacated or fully
bonded within ninety (90) days after its issue or levy.

                  6.5 Breach. Upon any breach or default of a material term
under this Agreement by SCS, this Agreement may be terminated upon ninety (90)
days' written notice to SCS. Said notice shall become effective at the end of
the ninety-day period, unless during said period SCS fully cures such breach or
default of a material term and notifies ROCHE of such cure. Such 90-day cure
period shall not apply to any uncontested royalty payments due, which
uncontested payments must be made in accordance with the terms of this
Agreement

                  6.6 Upon termination of this Agreement as provided herein, all
rights and licenses granted to SCS by ROCHE hereunder shall automatically revert
to or be retained by ROCHE.


                                       26
<PAGE>


                  6.7 SCS' obligations to report to ROCHE and to pay royalties
as to the sale of products licensed hereunder pursuant to the Agreement prior to
termination or expiration of the Agreement shall survive such termination or
expiration.

         7.       ENFORCEMENT OF PATENTS

                  7.1 SCS shall advise ROCHE promptly, and shall furnish
documentary proof which is reasonably acceptable to ROCHE, upon its becoming
aware of substantial infringement by a third party or parties of an enforceable
patent right within (1) TAQ PATENT RIGHTS by the sale of "Significant
Quantities" of unlicensed stand-alone enzymes in any country in the TERRITORY,
or (2) AMPLIFICATION PATENT RIGHTS by the sale of "Significant Quantities" of an
enzyme not within TAQ PATENT RIGHTS but which enzyme is actively promoted or
supported by said third party or parties or their affiliates or distributors for
use in AMPLIFICATION PATENT RIGHTS in any country in the TERRITORY. Upon receipt
of said written information, ROCHE agrees it shall, within its reasonable
business judgment, take such action as is required to restrain such
infringement. ROCHE shall be in full compliance with its obligations under this
Section 7.1 if, within six (6) months of ROCHE having received said written
information from SCS about any one infringing party in a particular country, (1)
ROCHE notifies each third party identified by such acceptable documentary proof
of ROCHE's enforceable proprietary position in the country where infringement
is occurring and receives from such third parties written assurance, which shall
be executed by an officer of each said third party capable of legally binding
that party, that it is not infringing ROCHE's rights, or (2) said infringement
has stopped, or (3) ROCHE has entered into good faith license negotiations with
such third parties, or (4) ROCHE has instituted or is prosecuting an action for
patent infringement against at least one infringing third party


                                       27
<PAGE>



sells in said country. The above six-month period may be extended with the
written consent of SCS.

         It is agreed and understood that, in accordance with the foregoing,
nothing in this Agreement shall require ROCHE to sue more than one party at a
time or to sue in more than one country at any one time.

         For the purposes of the foregoing clause, "Significant Quantities"
shall mean (1) in the case of a single third-party infringer in a particular
country, at least ***, or (2) in the case of more than one third-party seller in
a particular country, at least ***, of total unit turnover, respectively, of
stand-alone enzyme(s) within TAQ PATENT RIGHTS or thermostable enzymes actively
promoted for use in AMPLIFICATION PATENT RIGHTS, in each country, the accuracy
of said *** or *** figures being acceptable to both parties. "Actively promoted"
shall mean advertised or technically supported for use in AMPLIFICATION PATENT
RIGHTS.

         If ROCHE is provided with the documentary proof of continued infringing
sales as above described and ROCHE does not within the six-month period pursue
one of the above options, SCS shall have the right at the expiration of the
six-month period, or such other period as the parties have agreed, to reduce its
royalty rate for royalties owed on stand-alone TAQ REAGENTS or stand-alone SCS
ENZYMES in said country by ***. SCS' right to reduce its royalties shall
terminate and SCS shall resume paying full royalties in each country, as of the
time: (1) all such infringing third parties in such country have either
delivered the written assurances described above or engaged in good faith
license negotiations with ROCHE, provided that if said negotiations do not
conclude within one year, SCS may again abate its royalty by ***, as the case
may be, in the manner described above until the conclusion of a license with
said third party; or (2) the filing or prosecution of an



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                                       28
<PAGE>


infringement suit against at least one such party in said country; or (3) as a
result of the written assurances received in accordance with the foregoing or
the conclusion of any licenses or litigations or otherwise, infringement in fact
ceases or is reduced to below "Significant Quantities". Notwithstanding the
provisions of this clause, ROCHE and SCS understand and specifically agree that
nothing in this Agreement shall reduce SCS' royalty below *** per unit of Taq
DNA Polymerase.

         8.       Confidentiality-Publicity

                  8.1 To the extent that, in literature for distribution to
third parties, SCS or its AFFILIATES refer to ROCHE, P-E or the terms of this
Agreement, solely by specific inclusion of the clause provided in Section 2.11,
ROCHE hereby approves of such usage and no further ROCHE review or approval
shall be required for distribution of said literature. If SCS varies from the
agreed-to clause in section 2.11, then SCS agrees to obtain ROCHE's written
approval prior to distributing any written information including said modified
reference to ROCHE, P-E or the terms of this Agreement. ROCHE's approval shall
not be unreasonably withheld or delayed and, in any event, its decision shall be
rendered within three (3) weeks of receipt of the written information. Once
approved, such materials, or abstracts of such materials, which do not
materially alter the content of the material originally approved may be
reprinted during the term of the Agreement without further approval by ROCHE
unless ROCHE has notified SCS in writing of its decision to withdraw permission
for such use.

                  8.2 Each party agrees that any financial, legal or business
information or any technical information disclosed to it (the "Receiving Party")
by the other (the "Disclosing Party") in connection with this Agreement and
identified in writing as



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                                       29
<PAGE>


confidential in connection with this Agreement shall be considered confidential
and proprietary and the Receiving Parry shall not disclose same to any third
party and shall hold it in confidence for a period of five (5) years and will
not use it other than as permitted under this Agreement provided, however, that
any information, know-how or data which is orally disclosed to the Receiving
Party shall not be considered confidential and proprietary unless such oral
disclosure is reduced to writing and marked confidential and given to the
Receiving Party in written form within thirty (30) days after oral disclosure
thereof. Such confidential and proprietary information shall include, without
limitation, marketing and sales information, commercialization plans and
strategies, research and development work plans, and technical information such
as patent applications, inventions, trade secrets, systems, methods, apparatus,
designs, tangible material, organisms and products and derivatives thereof.
Notwithstanding the above, Roche shall have the right to share royalty reports
with P-E.

                  The above obligations of confidentiality shall not be
applicable to the extent that:

                  a)       such information is general public knowledge or,
                           after disclosure hereunder, becomes general or
                           public knowledge through no fault of the Receiving
                           Party; or

                  b)       such information can be shown by the Receiving Party
                           by its written records to have been in its possession
                           prior to receipt thereof hereunder, or



                                       30
<PAGE>
                    c)  such  information  is received by the Receiving  Party
                        from any  third  party for  use or  disclosure  by the
                        Receiving   Party   without  any   obligation  to  the
                        Disclosing  Party provided,  however, that information
                        received by the  Receiving  Party from any third party
                        funded by the  Disclosing  Party  (e.g.,  consultants,
                        subcontractors,  etc.)  shall  not  be  released  from
                        confidentiality under this exception; or

                    d)  the disclosure of such information is required or
                        desirable to comply with or fulfill, governmental
                        requirements, submissions to governmental bodies, or the
                        securing of regulatory approvals.

            8.4 Each party shall, to the extent reasonably practicable, maintain
the confidentiality of the provisions of this Agreement and shall refrain from
making any public announcement or disclosure of this Agreement or its terms
without the prior consent of the other party, which consent shall not be
unreasonably withheld, except to the extent a party concludes in good faith that
such disclosure is required under applicable law or regulations, in which case
the other party shall be notified in advance.

      9. ASSIGNMENT

            9.1 This Agreement shall not be assigned by SCS (including without
limitation any purported assignment or transfer that would arise from a sale or
transfer of SCS' business). Except as is provided in Section 6.3, this license
shall remain in force if Stratagene is acquired in its entirety or in its
entirety except for its mutagenesis business by



                                       31
<PAGE>
a third party so long as Stratagene remains a discrete business unit, operates
under the name of Stratagene, and manufactures and sells licensed products under
the name Stratagene.

            9.2 ROCHE may assign all or any part of its rights and obligations
under this Agreement at any time without the consent of SCS. SCS agrees to
execute such further acknowledgments or other instruments as ROCHE may
reasonably request in connection with such assignment.

      10. NEGATION OF WARRANTIES AND INDEMNITY

            10.1  Nothing in this Agreement shall be construed as:

                    a)  a warranty or representation by ROCHE as to the validity
                        or scope of any patent included within TAQ PATENT
                        RIGHTS, AMPLIFICATION PATENT RIGHTS or SEQUENCING PATENT
                        RIGHTS;

                    b)  a warranty or representation that the practice of TAQ
                        PATENT RIGHTS, AMPLIFICATION PATENT RIGHTS or SEQUENCING
                        PATENT RIGHTS is or will be free from infringement of
                        patents of third parties;

                    c)  an obligation to bring or prosecute actions or suits
                        against third parties for infringement, provided
                        however, that this clause shall not alter SCS' rights
                        and ROCHE's obligations under Section 7.1;



                                       32
<PAGE>
                    d)  except as expressly set forth herein, conferring the
                        right to use in advertising, publicity or otherwise any
                        trademark, trade name, or names, or any contraction,
                        abbreviation, simulation or adaptation thereof, of ROCHE
                        or P-E;

                    e)  conferring by implication, estoppel or otherwise any
                        licenses, immunities or rights under any patents or
                        patent applications of ROCHE other than those specified
                        in TAQ PATENT RIGHTS and AMPLIFICATION PATENT RIGHTS and
                        SEQUENCING PATENT RIGHTS, regardless of whether such
                        other patents or patent applications are dominant or
                        subordinate to those in TAQ PATENT RIGHTS,
                        AMPLIFICATION PATENT RIGHTS or SEQUENCING PATENT RIGHTS,
                        or under any thermal cycler or other instrument patent,
                        or to perform PCR in a thermal cycler that is not an
                        AUTHORIZED THERMAL CYCLER or a LICENSED THERMAL CYCLER,
                        or to make or sell any thermal cycler or other
                        instrument for the automated performance of the PCR
                        Process;

                    f)  an obligation to furnish any know-how not provided in
                        TAQ PATENT RIGHTS, AMPLIFICATION PATENT RIGHTS, and
                        SEQUENCING PATENT RIGHTS; or

                    g)  creating any agency, partnership, joint venture or
                        similar relationship between ROCHE and/or P-E on the one
                        hand, and SCS on the other hand.



                                       33
<PAGE>
            10.2  ROCHE MAKES NO EXPRESS OR IMLIED WARRANTIES OF
MERCHANTABILTY OR FITNESS FOR A PARTICULAR PURPOSE.

            10.3 Notwithstanding the foregoing, ROCHE warrants and represents
that it has the right and authority to enter into this Agreement and to grant
the licenses provided in Sections 2 and 5.

        11. INDEMNITY.

            11.1 SCS shall assume full responsibility for its use of TAG PATENT
RIGHTS and for its sale of Taq and LICENSED PRODUCTS and shall defend, indemnify
and hold ROCHE and P-E and their respective officers, directors, agents,
employees, and stockholders, harmless from and against all liability, demands,
damages, expenses (including attorneys' and expert witness fees and expenses)
and losses for death, personal injury, illness or property damage, or any other
injury or damage arising out of the use by SCS of the TAQ PATENT RIGHTS or the
preparation, use or sale of LICENSED PRODUCTS, including but not limited to, use
or reliance upon such LICENSED PRODUCTS by customers of SCS or its Affiliates.


      12. MOST FAVORED LICENSEE.

          12.1 If after the Effective Date, ROCHE grants to any unrelated third
party, other than P-E, ROCHE's exclusive distributor in Licensed Fields, a
license of substantially the same scope as granted to SCS herein ***, ROCHE
shall promptly notify SCS of ***, and SCS shall have the right and



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    the Commission. Confidential treatment has been requested with respect to
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                                       34
<PAGE>



option ***. In addition, if ROCHE grants a license to such an unrelated third
party in one or more Licensed Fields that is not of the same scope as SCS'
license hereunder (for example, because such license is limited to the field of
Forensics) ***, SCS shall have the right and option to ***. SCS' right to ***
shall extend only for so long as and shall be conditioned on SCS' acceptance of
all the same terms and conditions, favorable or unfavorable, under which ***
shall be available to such other third party. Upon SCS' acceptance of ***, the
*** shall be effective as to SCS on the effective date of ***. Notwithstanding
the foregoing, in the event that ROCHE and/or P-E shall receive substantial
other non-monetary consideration, for example, such as intellectual property
rights, as a part of the consideration for ***, then this Section 12.1 shall not
apply, except to the extent ROCHE grants to any unrelated third party other than
Perkin-Elmer rights to *** for ***.

        With the exception of the "grant to Roche", Section 3 herein, as of the
date of this Agreement, Roche has not granted to *** a license of ***.


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   the Commission. Confidential treatment has been requested with respect to the
   omitted portions.


                                       35
<PAGE>


        ***


        13. GENERAL

            13.1 This Agreement constitutes the entire agreement between SCS and
ROCHE as to the subject matter hereof, and all prior negotiations,
representations, agreements and understandings are merged into, extinguished by
and completely expressed by it. This Agreement may be modified or amended only
by a writing executed by authorized officers of each of The Parties.

            Any notice required or permitted to be given by this Agreement shall
be given by postpaid, first class, registered or certified mail, or by courier
or facsimile, properly addressed to the other party or parties at the respective
address as shown below:

If to ROCHE:

                    Roche Molecular Systems, Inc.
                    340 Kingsland Street
                    Nutley, New Jersey 07110
                    Attn: Corporate Secretary

with a copy to:

                    Roche Molecular Systems, Inc.
                    1145 Atlantic Avenue, Suite 100
                    Alameda, California 94501
                    Attn:  Licensing Manager



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   omitted portions.




                                       36
<PAGE>
If to SCS:
                    Stratagene
                    11099 North Torrey Pines Road
                    La Jolla, California 92037
                    Attn:  Dr. Joseph A. Sorge
                           Chief Executive Officer

with a copy to:

                    Stratagene
                    11099 North Torrey Pines Road
                    La Jolla, California 92037
                    Attn:  Ronni L. Sherman
                           V. P. and General Counsel

Either party may change its address by providing notice to the other party.
Unless otherwise specified herein, any notice given in accordance with the
foregoing shall be deemed given within four (4) full business days after the day
of mailing, or one full day after the date of delivery to the courier, or the
date of facsimile transmission, as the case will be.

            13.2 Governing Law and Venue. This Agreement and its effect are
subject to and shall be construed and enforced in accordance with the law of the
State of New Jersey, U.S.A., except as to any issue which by the law of New
Jersey depends upon the validity, scope or enforceability of any patent within
AMPLIFICATION PATENT RIGHTS, TAQ PATENT RIGHTS, or SEQUENCING PATENT RIGHTS
which issue shall be determined in accordance with the applicable patent laws of
the United States or the relevant foreign jurisdiction. The parties agree that
the exclusive jurisdiction and venue for any dispute or controversy arising from
this Agreement shall be in the United States District Court for the District of
New Jersey if federal jurisdiction exists, and if no federal jurisdiction
exists, then in the Superior Court of New Jersey.



                                       37
<PAGE>
            13.3 Arbitration. Notwithstanding the provisions of Section 13.2
above, any dispute concerning solely the determination of facts such as, but not
limited to, (1) what constitutes a quantity significantly exceeding a SCS
customer's typical usage requirements pursuant to Section 2.10 (b); (2) a
determination of royalty rate payments owed pursuant to Section 4.1; (3) the
circumstances triggering royalty reduction pursuant to Section 4.5; (4) the
determination of the unlicensed competition and concomitant royalty abatement
pursuant to Section 7, Patent Enforcement clause; and which dispute does not
involve a question of law, shall be settled by final and binding arbitration at
a mutually convenient location in the State of New Jersey pursuant to the
commercial arbitration rules of the American Arbitration Association in
accordance with the following procedural process:

                    (a) The arbitration tribunal shall consist of three
                        arbitrators. Each party shall nominate in the request
                        for arbitration and the answer thereto one arbitrator
                        and the two arbitrators so named will then jointly
                        appoint the third arbitrator within sixty (60) days of
                        the filing of the answer, said third arbitrator being
                        the chairman of the arbitration tribunal.

                    (b) The decision of the arbitration tribunal shall be final
                        and judgement upon such decision may be entered in any
                        competent court for juridical acceptance of such an
                        award and order of enforcement.

      Each party hereby submits itself to the jurisdiction of the courts of the
place of arbitration, but only for the entry of judgment with respect to the
decision of the arbitrator's hereunder.



                                       38
<PAGE>
            13.4 Nothing in this Agreement shall be construed so as to require
the commission of any act contrary to law, and wherever there is any conflict
between any provision of this Agreement or concerning the legal right of the
parties to enter into this Agreement and any statute, law, ordinance or treaty,
the latter shall prevail, but in such event the affected provisions of the
Agreement shall be curtailed and limited only to the extent, necessary to bring
it within the applicable legal requirements.

            13.5 If any provision of this Agreement is held to be unenforceable
for any reason, it shall be adjusted rather than voided, if possible, in order
to achieve the intent of the party to the extent possible. In any event, all
other provisions of this Agreement shall be deemed valid and enforceable to the
full extent possible.



                                       39
<PAGE>
      IN WITNESS WHEREOF, The Parties hereto have set their hands and seals and
duly executed this Agreement on the date(s) indicated below.

ROCHE MOLECULAR SYSTEMS, INC.          STRATAGENE

By: /s/ KATHY ORDONEZ                  By: /s/ JOSEPH SORGE
   ----------------------------           --------------------------------------

Name: Kathy Ordonez                    Name: Joseph Sorge
      -------------------------             ------------------------------------
Title: President                       Title: Chairman & CEO
      -------------------------              -----------------------------------

Date: July 26, 1994                    Date: 7/7/94
     --------------------------             ------------------------------------
 APPRV'D As To Form
     LAW DEPT.
     By PJR

F. HOFFMANN-LA ROCHE LTD               F. HOFFMANN-LA ROCHE LTD

By:   [SIGNATURE ILLEGIBLE]            By: /s/ Dr. A. Junosza Jankowski
   ----------------------------           --------------------------------------

Name: [ILLEGIBLE]                      Name: Dr. A. Junosza Jankowski
    ---------------------------             ------------------------------------

Title: Authorized Signatory            Title: PLR Licensing Manager
      -------------------------              -----------------------------------

Date: July 19, 1994                    Date: July 20, 1994
     --------------------------             ------------------------------------



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                                   APPENDIX A

                                   STRATAGENE

                          Forensics and Human Identity

1. Field of Use: "Forensic and Human Identity Applications" shall mean the
forensic analysis of human genetic material for use in, or in preparation for,
legal proceedings, but shall exclude paternity determination except in case of
death investigation. This field specifically excludes tissue typing.

2. ***

                              ENVIRONMENTAL TESTING


1. Field of Use: "Environmental Testing Applications" shall mean testing and
monitoring environmental samples, including, without limitation, for the purpose
of detecting the presence or absence or amount of any organism or microorganism
(including, without limitation, viruses and bacteria), whether living, dead or
extinct, or their remains.

2. ***

                             PLANT DIAGNOSTICS

1. Field of Use: "Plant Diagnostics Applications" shall mean diagnostic
applications in plants, including, without limitation, the diagnosis of a
disease or condition, the diagnosis of susceptibility or resistance to a disease
or condition, or a choice of treatment of a disease or condition, the
determination of genetic traits for breeding purposes, or the identification of
a particular plant species.

2. ***

*** Certain information on this page has been omitted and filed separately with
    the Commission. Confidential treatment has been requested with respect to
    the omitted portions.

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                               ANIMAL DIAGNOSTICS

1. Field of Use: "Animal Diagnostics" shall mean detection of genetic disease,
genetic pre-disposition to disease, or other medical condition in animals for
any purpose except establishment of identity, and infectious disease testing in
animals. This field shall include sex determination but shall specifically
exclude parentage determination.

2. ***

3. Royalties on these products shall be as follows:

                (i) For products directed at detection of nucleic acids
associated with genetic disease, genetic traits, or infectious disease in
animals, ***% of the NET SALES PRICE of the kits, or *** per unit of TAQ REAGENT
or SCS ENZYME in the kit, whichever is higher.

                (ii) For products directed at sex determination in embryos, ***%
of the NET SALES PRICE of the kits, or *** per unit of TAQ REAGENT or SCS ENZYME
in the kit, whichever is higher.

               ANIMAL IDENTITY TESTING AND POSITIVE TRAIT BREEDING

1. Fields of Use: "Animal Identity Testing Applications" shall mean identity
testing for animals (other than humans), whether living, dead or extinct, or
their remains, including, without limitation, parentage testing. "Positive Trait
Breeding" shall mean the determination of genetic traits other than
disease-related traits for breeding purposes.

2. ***


*** Certain information on this page has been omitted and filed separately with
    the Commission. Confidential treatment has been requested with respect to
    the omitted portions.


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                                  FOOD TESTING

1. Field of Use: "Food Testing Applications" shall mean the detection and/or
analysis Of microorganisms in food or food/samples for quality assurance and
quality control Purposes.

2. ***


*** Certain information on this page has been omitted and filed separately with
    the Commission. Confidential treatment has been requested with respect to
    the omitted portions.


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                                   APPENDIX B

                       ASSAY TO DETERMINE UNITS OF ENZYME

I.      Taq DNA polymerase

        Taq DNA polymerase manufactured by SCS ("SCS-Taq") shall be assayed
        under the following conditions, in parallel with an assay of Roche
        Molecular Systems' AmpliTaq(R) DNA polymerase (P-E catalogue numbers
        N-801-0060, N-801-1012). The activity of SCS-Taq and AmpliTaq thus
        measured by SCS shall be normalized to the concentration stated by RMS
        for the AmpliTaq.

        Unit Definition:        One unit of enzyme is defined as the amount that
                                will incorporate l0nmoles of dNTPs into acid
                                insoluble material per 30 minutes at 74
                                (degrees) C under the analysis conditions below.

        Analysis conditions:    25mM TAPS (tris-(hydroxymethyl)-methyl-amino-
                                propanesulfonic acid, sodium salt), pH 9.3 (at
                                25 (degrees) C); 50mM KCl; 2 mM MgCl(2); 1mM
                                (beta)-mercaptoethanol; 200 (micrometer)M each
                                dATP, dGTP, dTTP; 100 (micrometer)M [is
                                proportional to-(32)P]-dCTP (0.05 to 0.1
                                Ci/mmole); activated salmon sperm DNA, mixed in
                                a final volume of 50 (micrometer)l and
                                incubated at 74 (degrees) C for 10 minutes. The
                                salmon sperm DNA is activated by a modification
                                of the methods in reference 1.

        The array mixture (without enzyme) is prepared fresh daily and 45
        (micrometer)l aliquots (0 (degrees) C) are mixed with 5 (micrometer)l
        of Taq DNA polymerase diluted in 25mM Tris-HCl pH8, 50mM KCl, 100
        (micrometer)g/ml autoclaved gelatin, lmM (beta)-mercaptoethanol, 0.5%
        w/v) NP40 and 0.5% (w/v) Tween20.

        Reactions are initiated with addition of enzyme and placed at 74
        (degrees) C. Reactions are quenched after 10 minutes with the addition
        of 10 (micrometer)l of 60mM EDTA and placed at 0 (degrees) C. Aliquots
        (50 (micrometer)l) are diluted with lml of 2mM EDTA containing
        50 (micrometer)g/ml sheared salmon sperm DNA, and precipitated by the
        addition of 1 ml 20% (w/v) acid and 2% (w/v) sodium pyrophosphate, and
        incubated at 0 (degrees) C for



                                       44
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        15 min. Precipitated DNA is collected on GF/C filter discs (2.4 cm) and
        washed extensively with 5% trichloroacetic acid and 2% sodium
        pyrophosphate (7 x 5 ml), then 95% ethanol (5ml), dried and counted.

        Activity concentration is determined from replicate assays (at least 3)
        of replicate parallel, serial dilutions (at least 3) that yield 20-90
        pMoles dCMP incorporation in the assay.

        Activated salmon sperm DNA is used at a concentration that provides
        linear incorporation values with 20-100 mU of enzyme. This DNA
        concentration usually represents 12.5-20(micron)g/assay.

II.     SCS Enzymes

        SCS enzymes shall be assayed in reference to AmpliTaq DNA polymerase (or
        another enzyme manufactured by ROCHE which is more comparable to the
        particular SCS enzyme) in a manner similar to that described above. The
        analysis conditions shall be adapted to reflect the optimal activity
        conditions for each such SCS enzymes. Further, the effectiveness of such
        enzyme in producing amplified DNA in the PCR Process shall be determined
        in comparison with AmpliTaq DNA polymerase under the optimal conditions
        for each enzyme. From this comparison a "PCR Effectiveness Ratio" will
        be derived to be used in determining the per unit royalty specified in
        section 4.1 c. The Parties agree that calculation of such a ratio is
        complex and can only be determined on a case-by-case basis. Such assays
        shall be agreed upon by ROCHE and SCS.

III.    For purposes of calculating royalties owed on products, the
        concentration of enzyme (units per volume) reported must be within
        +/-*** of the actual activity measured by the above assays. The volume
        of enzyme reported to be in a product must be within +/-*** of the
        actual measurable volume.

Ref. I Richardson. C.C. 1966. DNA Polymerase from Escherichia coli. in
Procedures in Nucleic Acid Research eds.Cantoni G.L. and Davies, D.R. Harper &
Row, New York, p. 264.


*** Certain information on this page has been omitted and filed separately with
    the Commission. Confidential treatment has been requested with respect to
    the omitted portions.



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<PAGE>

                                   APPENDIX C

                              NOTICES TO PURCHASER

1. License statement for use on TAQ REAGENTS and SCS ENZYMES designed and sold
for use in AMPLIFICATION PATENT RIGHTS and/or SEQUENCING PATENT RIGHTS.

                      NOTICE TO PURCHASER: LIMITED LICENSE

The purchase price of this product includes a limited, non-transferable license
under U.S. Patents 4,683,202, 4,683,195, 4,965,188, and 5,075,216 or their
foreign counterparts, owned by Hoffmann-La Roche Inc. and F.Hoffmann-La Roche
Ltd. ("Roche"), to use only this amount of the product to practice the
Polyrnerase Chain Reaction ("PCR") and related processes described in said
patents solely for the research and development activities of the purchaser when
this product is used in conjunction with an authorized thermal cycler. No right
to perform or offer commercial services of any kind using PCR, including without
limitation reporting the results of purchaser's activities for a fee or other
commercial consideration, is hereby granted by implication or estoppel. Further
information on purchasing licenses to practice the PCR process may be obtained
by contacting the Director of licensing at The Perkin-Elmer Corporation. 850
Lincoln Centre Drive, Foster City, California 94404 or at Roche Molecular
Systems, Inc., 1145 Atlantic Avenue, Alameda, California 94501.

2. For use on LICENSED RESEARCH PRODUCTS designed and sold for use in
AMPLIFICATION PATENT RIGHTS but not suitable for use in SEQUENCING PATENT
RIGHTS.


                      NOTICE TO PURCHASER: LIMITED LICENSE

The purchase price of this product includes a limited, non-transferable license
under U.S. Patents 4,683,202, 4,683,195 and 4,965,188 or their foreign
counterparts, owned by Hoffmann-La Roche Inc. and F.Hoffmann-La Roche Ltd.
("Roche"), to use only this amount of the product to practice the Polymerase
Chain Reaction ("PCR") and related processes described in said patents solely
for the research and development activities of the purchaser when this product
is used in conjunction with an authorized thermal cycler. No light to perform or
offer commercial services of any kind using PCR, including without limitation
reporting the results of purchaser's activities for a fee or other commercial
consideration, is



                                       46
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hereby granted by implication or estoppel. Further information on purchasing
licenses to practice the PCR process may be obtained by contacting the Director
of Licensing at The Perkin-Elmer Corporation, 850 Lincoln Centre Drive, Foster
City, California 94404 or at Roche Molecular Systems, Inc., 1145 Atlantic
Avenue, Alameda, California 94501.

3. For use on LICENSED RESEARCH PRODUCTS designed and sold for use in SEQUENCING
PATENT RIGHTS

                      NOTICE TO PURCHASER: LIMITED LICENSE

The purchase price of this product includes a limited, non-transferable license
under U.S. Patent 5,075,216 or its foreign counterparts, owned by Hoffmann-La
Roche Inc. and F.Hoffmann-La Roche Ltd. ("Roche"), to use only this amount of
the product for DNA Sequencing and related processes described in said patent
solely for the research and development activities of the purchaser. No license
under these patents to use the PCR process is conveyed expressly or by
implication to the purchaser by the purchase of this product. A license to use
the PCR process for certain research and development activities accompanies the
purchase of certain reagents from licensed suppliers such as Stratagene when
used in conjunction with an authorized thermal cycler, or is available from the
Perkin-Elmer Corporation. Further information on purchasing licenses to practice
the PCR process may be obtained by contacting the Director of Licensing at the
Perkin-Elmer Corporation, 850 Lincoln Centre Drive, Foster City, California
94404 or at Roche Molecular Systems, Inc., 1145 Atlantic Avenue, Alameda,
California 94501.

4. For use on research products which are not LICENSED RESEARCH PRODUCTS but
which are supported for use in PCR and/or with LICENSED RESEARCH PRODUCTS

                               NOTICE TO PURCHASER

This product is optimized for use in the Polymerase Chain Reaction ("PCR")
covered by patents owned by Hoffmann-La Roche Inc. and F.Hoffmann-La Roche Ltd.
("Roche"). No license under these patents to use the PCR process is conveyed
expressly or by implication to the purchaser by the purchase of this product. A
license to use the PCR process for certain research and development activities
accompanies the purchase of certain reagents from licensed suppliers such as
Stratagene when used in conjunction with an authorized



                                       47
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thermal cycle, or is available from the Perkin-Elmer Corporation. Further
information on purchasing licenses to practice the PCR process may be obtained
by contacting the Director of Licensing at the Perkin-Elmer Corporation, 850
Lincoln Centre Drive, Foster City, California 94404 or at Roche Molecular
Systems, Inc., 1145 Atlantic Avenue, Alameda, California, 94501.

5. Similar notices for use on LICENSED APPLICATIONS PRODUCTS will be provided as
are selected.



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<PAGE>
APPENDIX D


                             SUMMARY ROYALTY REPORT

                        FOR THE PERIOD ______ TO ______


                           COUNTRY: ________________

<Table>
<S>                                     <C>                                     <C>
LICENSE: STRATAGENE                                                             FIELD OF USE: PCR RESEARCH PRODUCTS

LICENSEE NUMBER: __________             EFFECTIVE DATE: ____________            ROYALTY RATE: __________

_________________________________________________________________________________________________________________________________
                     UNITS OF ENZYME   GROSS INVOICE    DISCOUNTS                   NUMBER OF    ROYALTY DETERMINED
                           IN            PRICE OF        ALLOWED    NET SALES    PRODUCT UNITS    ON ENZYME OR NET
LICENSED PRODUCT         PRODUCT          PRODUCT       (EXPLAIN)   OF PRODUCT       SOLD              SALES          ROYALTY DUE
_________________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________________

_________________________________________________________________________________________________________________________________
                                                                                TOTAL ROYALTY EARNED
        CHECK HERE IF THERE WERE NO SALES FOR THIS PERIOD ______                _________________________________________________
                                                                                APPLICABLE CREDIT
                                                                                _________________________________________________
                                                                                ROYALTY PAYMENT DUE
                                                                                _________________________________________________
</Table>

I hereby certify the information set forth above is correct and complete with
respect to the amounts due under the applicable license agreement.

By: ___________________________  Title: ___________________  Date: ____________
      (authorized signature)

Name (Please print): ________________________

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

         * Please attach supporting or supplemental data to this sheet