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                                                                     EXHIBIT 4.2

                         COMMON STOCK PURCHASE AGREEMENT

        This Common Stock Purchase Agreement (the "Agreement") is made as of
August 27, 2001, by and between Geron Corporation, a Delaware corporation ("the
Company"), and University Technology Corporation, a Colorado not-for-profit
corporation ("UTC").

        WHEREAS, UTC and the Company have entered into a First Amendment to
Intellectual Property License Agreement (the "Agreement") having an effective
date of July 23, 2001.

        WHEREAS, pursuant to Section 17 of the Agreement, the Company has agreed
to issue to UTC one hundred thousand (100,000) shares of the Company's Common
Stock (the "Shares") in consideration of the execution of the Agreement and the
mutual promises and covenants thereunder.

        NOW, THEREFORE, for good and valuable consideration, the receipt and
adequacy of which is hereby acknowledged, the Company and UTC hereby agree as
follows:

        1.      The Company agrees to issue to UTC the Shares. The issuance of
the Shares shall take place at such time and place upon which the Company and
UTC mutually agree, either orally or in writing, but, in no event later than
seven (7) days after the effective date of the Form S-3 registration of the
Shares by the Company (the "Closing"). The Company agrees to file such an S-3
registration statement within ten (10) business days after the date of execution
of the Agreement, and to diligently pursue making that registration statement
effective. At the Closing, or within ten (10) business days thereafter, the
Company will deliver to UTC a certificate representing the Shares, which shall
be freely tradeable.

        2.      In connection with the issuance of the Shares, UTC represents to
the Company the following:

               (a) UTC is aware of the Company's business affairs and financial
condition and has acquired sufficient information about the Company to reach an
informed and knowledgeable decision to acquire the Shares.

               (b) UTC represents that UTC has consulted with any tax
consultants UTC deems advisable in connection the acquisition or disposition of
the Shares and that UTC is not relying on the Company for any tax advice.

        3.      This Agreement may be executed in one or more counterparts each
of which shall be deemed an original, but all of which together shall constitute
one and the same.

        4.      This Agreement shall be governed by and construed in accordance
with the laws of the State of Colorado applicable to contracts entered into and
to be performed entirely within the State of Colorado by residents of the State
of Colorado. This Agreement constitutes the entire agreement of the parties
pertaining to the Shares and supersedes all prior and contemporaneous
agreements, representations, and understandings of the parties.


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        IN WITNESS WHEREOF, the undersigned, by each of their respective duly
authorized officers and representatives, have set forth their hands hereto to be
effective as of the date first set forth above.

GERON CORPORATION                         UNIVERSITY TECHNOLOGY CORPORATION


--------------------------------------    -------------------------------------
Name:  David L. Greenwood                 Name:
Title:  Sr. Vice President, Corporate          --------------------------------
Development and CFO                       Title:

Date:  August 27, 2001                          -------------------------------
                                          Date:
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