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                                                                     EXHIBIT 4.1

                    FIRST AMENDMENT TO INTELLECTUAL PROPERTY
                                LICENSE AGREEMENT

        This First Amendment to Intellectual Property License Agreement
("Amendment") is made as of July 23, 2001 (the "Effective Date"), by and between
UNIVERSITY TECHNOLOGY CORPORATION, a not-for-profit Colorado corporation having
its principal place of business at 4001 Discovery Drive, Suite 390, 588 UCB,
Boulder, Colorado 80309-0588 ("UTC") and GERON CORPORATION, a Delaware
corporation having its principal place of business at 230 Constitution Drive,
Menlo Park, California 94025 ("Geron" or "Licensee").

        WHEREAS, UTC and Geron are the co-owners of certain intellectual
property rights including, without limitation, U.S. patent number 6,261,836 and
foreign equivalents (the "Licensed Rights"); and

        WHEREAS, UTC and Geron are the parties to an Intellectual Property
License Agreement dated December 9, 1996 (the "License Agreement") under which
UTC grants to Geron, on the terms and conditions of the License Agreement, an
exclusive license under UTC's undivided interest in the Licensed Rights; and

        WHEREAS, UTC and Geron have concluded that it is in each of their
interests to amend the License Agreement in certain respects;

        NOW, THEREFORE, in consideration of the promises and the mutual
covenants contained herein, the parties agree as follows:

1.      Section 1.3 of the License Agreement is amended to read as follows:

        A "Licensed Product" shall mean any product or part thereof which is
        sold, manufactured, or used in any country under this Agreement and
        which:

                (a)     is covered in whole or in part by an issued, unexpired
                        claim or a pending claim contained in the Intellectual
                        Property Rights in the country in which any Licensed
                        Product is made, used or sold; or

                (b)     is manufactured using a Licensed Process which is
                        covered in whole or in part by an issued, unexpired
                        claim or a pending claim contained in the Intellectual
                        Property Rights in the country in which any Licensed
                        Process is used or in which such product or part thereof
                        is used or sold; or

                (c)     is created using Know-How included in Intellectual
                        Property Rights provided hereunder, and used prior to
                        the Know-How entering the public domain.


[ *** ] Confidential portion has been filed separately with the Securities
        and Exchange Commission.


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2.      Section 1.4 of the License Agreement is amended to read as follows:

        A "Licensed Process" shall mean any process which is used in any country
        under this Agreement and which:

                (a)     is covered in whole or in part by an issued, unexpired
                        claim or a pending claim contained in the Intellectual
                        Property Rights; or

                (b)     is created using Know-How included in Intellectual
                        Property Rights provided hereunder, and used prior to
                        the Know-How entering the public domain.

3.      Section 1.5 of the License Agreement is amended to delete the words
        "and/or its sublicensee" in the first sentence.

4.      Article I of the License Agreement is amended to add the following new
        sections:

        1.10    "Sub-Licensing Revenues" shall mean any and all revenues
        received by Geron from a sublicensee for the grant of any sublicense
        under this Agreement, including without limitation up-front license
        fees, annual license maintenance fees, milestone payments, royalty
        payments, equity, and share of profits, but excluding Research
        Reimbursement. If Geron receives Sub-Licensing Revenues in the form of
        non-cash consideration other than equity, the fair market value of such
        non-cash consideration shall be used for purposes of calculating
        Sub-Licensing Revenues, and UTC's share of such fair market value under
        Section 4.1(d) shall be paid in cash.

        1.11    "Research Reimbursement" shall mean amounts received by Geron
        from a sublicensee to reimburse Geron for bona fide expenditures for
        research employees (using Geron's usual FTE rate), laboratory supplies
        and equipment, and other out-of-pocket expenses for research and
        development work conducted under a provision in the sublicense agreement
        or a contemporaneous written agreement between Geron and the
        sublicensee, provided that (i) such agreement reasonably defines the
        work to be done, (ii) such work is reasonably required for sublicensee's
        commercialization of Licensed Technologies, and (iii) the work is
        performed after or within [***] before the execution of the agreement.

        1.12    "ESC Research Products" shall mean products or services
        consisting of or based on cells derived from embryonic stem cells for
        use in drug discovery and/or development or other research.


[ *** ] Confidential portion has been filed separately with the Securities
        and Exchange Commission.


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5.      Section 2.5 of the License Agreement is amended to read as follows:

        LICENSEE shall have the right to enter into sublicensing agreements for
        the rights, privileges and licenses granted hereunder. LICENSEE shall
        provide written notification of the identity of the sublicensee and, to
        the extent defined, the scope of the sublicense (i.e. exclusive or
        nonexclusive and any field limitations) no later than the earliest of
        (i) the signing of a letter of intent or term sheet with the licensee,
        (ii) [***} before signing an agreement granting an option to obtain a
        sublicense, or (iii) [***] before signing a sublicense agreement. Only
        one such notification is required for each sublicense. Any such
        notification will be sent by overnight express mail to UTC and to the
        Office of Technology Transfer at the University of Colorado Health
        Sciences Center. Any such notification shall be treated as confidential
        under the confidentiality agreements between LICENSEE and UTC and
        LICENSEE and the University of Colorado.

6.      Section 2.6 of the License Agreement is amended to read as follows:

        LICENSEE hereby agrees that nothing in any sublicense agreement shall
        restrict the sublicensee from seeking a license from UTC in the event
        this License Agreement is terminated for any reason and the sublicensee
        wishes to obtain such a license from UTC.

7.      Section 2.7 of the License Agreement is amended to read as follows:

        LICENSEE agrees that any sublicenses granted by LICENSEE shall be
        consistent with the terms and conditions of this Agreement. Each
        sublicense shall require the sublicensee to diligently pursue the
        commercialization of the sublicensed technology, and LICENSEE's due
        diligence obligations under Article III of this Agreement shall include
        commercially reasonable efforts to monitor and require compliance with
        the diligence provisions of such sublicenses. LICENSEE's failure to
        comply with its obligations to UTC under this Agreement shall not be
        excused by any default by a sublicensee under a sublicense agreement.

8.      Section 2.8 of the License Agreement is amended to delete the phrase
        "and to guarantee the performance of that sublicensee under any such
        agreement."

9.      Section 2.9 of the License Agreement is deleted in its entirety.

10.     Section 3.2(c) of the License Agreement is amended to read as follows:

        LICENSEE shall have Net Sales and/or Sub-Licensing Revenues in such
        amounts as to result in payments to UTC at least equal to the following
        amounts


[ *** ] Confidential portion has been filed separately with the Securities
        and Exchange Commission.


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        in the following years, beginning [ *** ] after successfully cloning the
        genes encoding the protein component or components of human telomerase:


<TABLE>
<CAPTION>
               Year                     Amount
               ----                     ------
<S>                                     <C>
               [ *** ]                  [ *** ]
               [ *** ]                  [ *** ]
               [ *** ]                  [ *** ]
               [ *** ],                 [ *** ]
</TABLE>


        If LICENSEE does not have actual Net Sales and/or Sub-Licensing Revenues
        in such amounts, LICENSEE shall comply with this section 3.2(c) by
        paying UTC the difference between such amounts and the payments made by
        LICENSEE under Section 4.1(c) and (d) based on actual Net Sales and
        Licensing Revenues.

11.     Section 3.3 of the License Agreement is revised to read as follows:

        LICENSEE's failure to perform in accordance with Paragraphs 3.1 and 3.2
        above shall be grounds for UTC to terminate this Agreement pursuant to
        Paragraph 12.3 hereof, unless LICENSEE makes the payments specified in
        Section 3.2(c), or both parties renegotiate the Due Diligence plan and
        mutually agree to revisions thereto.

12.     Section 4.1(c) of the License Agreement is amended to delete the words
        "or sublicensee" from the first sentence.

13.     Section 4.1(d) of the License Agreement is amended to read as follows:

                In addition to the foregoing, LICENSEE agrees that it will remit
                to UTC [ *** ] of all Sub-Licensing Revenues, except that for
                Sub-Licensing Revenues from sublicenses of the Intellectual
                Property Rights for use in ESC Research Products, LICENSEE will
                remit to UTC [ *** ] of such Sub-Licensing Revenues.

14.     Section 5.2 of the License Agreement is amended to change "forty-five
        (45) days" in the first sentence to "seventy-five (75) days."

15.     Article XI of the License Agreement is amended to read as follows:

        This Agreement is not assignable and any attempt to do so shall be void;
        provided, however, that either party may assign this Agreement to any
        party acquiring all or substantially all of the assets and business of
        such party (or of a division or other business unit of such party
        comprising such party's principal business related to the Intellectual
        Property Rights); and further provided that UTC may assign this
        Agreement to the University of Colorado.


[ *** ] Confidential portion has been filed separately with the Securities
        and Exchange Commission.


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16.     In all other respects, the License Agreement remains unchanged and in
        full force and effect.

17.     In consideration for the amendment of the License Agreement as provided
        in this Amendment, Geron will issue to UTC or its designee, within
        [ *** ] after the execution of this Amendment, One Hundred Thousand
        (100,000) shares of Geron common stock, pursuant to a Common Stock
        Purchase Agreement attached as Exhibit A to this Amendment, and a
        warrant for One Hundred Thousand (100,000) shares of Geron common stock,
        pursuant to a Warrant Agreement attached as Exhibit B to this Amendment.
        The exercise price for the warrant will be equal to the closing price of
        the common stock on the day prior to the execution of this Amendment.


IN WITNESS WHEREOF, the parties have executed this Amendment as of the Effective
Date.


UNIVERSITYTECHNOLOGY CORPORATION


By:     s/Girish Barua
    ----------------------------------------
        Dr. Girish Barua
        Co-Director
        Technology Transfer Office
        University of Colorado Health Sciences Center


Date:   8/30/2001
     ---------------------------------------



GERON CORPORATION


By:     s/David L. Greenwood
    ----------------------------------------
        David L. Greenwood
        Chief Financial Officer and Senior Vice President,
            Corporate Development


Date:   8/27/01
    ----------------------------------------


[ *** ] Confidential portion has been filed separately with the Securities
        and Exchange Commission.


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                                    EXHIBIT A
                         COMMON STOCK PURCHASE AGREEMENT


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                                    EXHIBIT B
                                WARRANT AGREEMENT