EXHIBIT 4.2



                         COMMON STOCK PURCHASE AGREEMENT

THIS COMMON STOCK PURCHASE AGREEMENT ("Agreement") is made and entered into as
of April 6, 2005 (the "Effective Date"), by and between GERON CORPORATION, a
Delaware corporation having its principal place of business at 230 Constitution
Drive, Menlo Park, California 94025 ("Geron"), and TRANSGENOMIC, INC., a
Delaware corporation having its principal place of business at 12325 Emmet
Street, Omaha, Nebraska 68164 ("Transgenomic").

     A.   Geron and Transgenomic are the parties to that certain Supply
          Agreement dated as of June 15, 2002 (the "Supply Agreement"), and
          related Addendum Agreements ("Addendum Agreement") under which Geron
          has agreed to purchase certain products from Transgenomic and
          Transgenomic has agreed to supply such products to Geron on the terms
          set forth therein.

     B.   Pursuant to Addendum Agreement No. 10, dated as of April 6, 2005,
          Geron may pay the purchase price of products by delivery of shares of
          Geron's Common Stock (the "Shares").

THE PARTIES AGREE AS FOLLOWS:

    1. ISSUANCE OF SHARES; ADJUSTMENTS.

           1.1    As payment of the First Installment specified in Addendum
                  Agreement No. 10, Geron will issue and deliver certificates
                  for 25,796 Shares. Upon issuance and delivery of the
                  certificate(s) for the Shares, all Shares shall be duly
                  authorized and validly issued and represent fully paid shares
                  of Geron's Common Stock.

    2. CLOSING; DELIVERY.

           2.1    The consummation of the transaction contemplated by this
                  Agreement (a "Closing") shall be held at such time and place
                  as is mutually agreed upon between the parties, but in any
                  event no later April 13, 2005 (the "Closing Date"). At the
                  Closing, Geron shall deliver to Transgenomic one or more
                  certificates representing all of the Shares, which Shares
                  shall be issued in the name of Transgenomic or its designee
                  and in such denominations as Transgenomic shall specify.

           2.2    Geron's obligations to issue and deliver the stock
                  certificate(s) representing the Shares to Transgenomic at the
                  Closing shall be subject to the following conditions, which
                  may be waived by Geron:

                  2.2.1  the covenants and obligations that Transgenomic is
                         required to perform or to comply with pursuant to this
                         Agreement, at or prior to the Closing, must have been
                         duly performed and complied with in all material
                         respects; and

                  2.2.2  the representations and warranties made by Transgenomic
                         herein shall be true and correct in all material
                         respects as of the Closing Date.

           2.3    Transgenomic's obligation to accept delivery of the stock
                  certificate(s) representing the Shares at the Closing shall be
                  subject to the following conditions, any one or more of which
                  may be waived by Transgenomic:

                  2.3.1  the covenants and obligations that Geron is required to
                         perform or to comply with pursuant to this Agreement,
                         at or prior to the Closing, must have been duly
                         performed and complied with in all material respects;

                                       1

<PAGE>

                  2.3.2  Geron shall have available under its Certificate of
                         Incorporation sufficient authorized shares of Common
                         Stock to issue the Shares to Transgenomic; and

                  2.3.3  the representation and warranties made by the Geron
                         herein shall be true and correct in all material
                         respects as of any Closing Date.

    3. RESTRICTIONS ON RESALE OF SHARES.

           3.1    Legends. Transgenomic understands and acknowledges that the
                  Shares are not registered under the Securities Act of 1933
                  (the "Act"), and that under the Act and other applicable laws
                  Transgenomic may be required to hold such Shares for an
                  indefinite period of time. Each stock certificate representing
                  Shares shall bear the following legends:

                  "THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED
                  UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE "ACT"). ANY
                  TRANSFER OF SUCH SECURITIES SHALL BE INVALID UNLESS A
                  REGISTRATION STATEMENT UNDER THE ACT IS IN EFFECT AS TO SUCH
                  TRANSFER OR, IN THE OPINION OF COUNSEL REASONABLY ACCEPTABLE
                  TO GERON, SUCH REGISTRATION IS UNNECESSARY FOR SUCH TRANSFER
                  TO COMPLY WITH THE ACT. THE SECURITIES REPRESENTED HEREBY ARE
                  SUBJECT TO THE TERMS OF THE COMMON STOCK PURCHASE AGREEMENT,
                  DATED AS OF APRIL 6, 2005. A COPY OF THE AGREEMENT CAN BE
                  OBTAINED FROM THE SECRETARY OF GERON."

           3.2    Limits on Sales. Transgenomic agrees that if it decides to
                  resell some or all of the Shares, it will do so only in an
                  appropriate manner based upon whether the shares are
                  registered or unregistered, i.e., on the Nasdaq National
                  Market or in a Rule 144A compliant transaction. Subject to the
                  foregoing restrictions, Transgenomic may sell or resell the
                  Shares in any lot size, or at any volume, desired by
                  Transgenomic.

    4. REGISTRATION RIGHTS

           4.1    Geron agrees to make commercially reasonable best efforts to
                  file with the Securities and Exchange Commission (the
                  "Commission") within five (5) business days after the Closing
                  Date, a registration statement under the Act (the
                  "Registration Statement"), on Form S-3 or other appropriate
                  form, so as to permit a non-underwritten public offering and
                  resale of the Shares under the Act by Transgenomic. Geron
                  agrees to diligently pursue making the Registration Statement
                  effective. Geron will notify Transgenomic of the effectiveness
                  of the Registration Statement within one (1) business day of
                  receiving notice from the Commission.

           4.2    Geron will maintain the Registration Statement and any
                  post-effective amendment thereto filed under this Section 4
                  effective under the Act until the earliest of (i) the date
                  that none of the Shares covered by such Registration Statement
                  are issued and outstanding, (ii) the date that all of the
                  Shares have been sold pursuant to such Registration Statement,
                  (iii) the date Transgenomic receives an opinion of counsel to
                  Geron, which counsel shall be reasonably acceptable to
                  Transgenomic, that the Shares may be sold under the provisions
                  of Rule 144 without limitation as to volume, (iv) the date
                  that all Shares have been otherwise transferred to persons who
                  may trade such shares without restriction under the Act, and
                  Geron has delivered a new certificate or other evidence of
                  ownership for such securities not bearing a restrictive
                  legend, or (v) the date all Shares may be sold at any time,
                  without volume or manner of sale limitations pursuant to Rule
                  144(k) or any similar provision then in effect under the Act
                  in the opinion of counsel to Geron, which counsel shall be
                  reasonably acceptable to Transgenomic.

                                       2

<PAGE>

           4.3    Geron, at its expense, shall furnish to Transgenomic with
                  respect to the Shares registered under the Registration
                  Statement such reasonable number of copies of the Registration
                  Statement, prospectuses and preliminary prospectuses in
                  conformity with the requirements of the Act and such other
                  documents as Transgenomic may reasonably request, in order to
                  facilitate the public sale or other disposition of all or any
                  of the Shares by Transgenomic, provided, however, that the
                  obligation of Geron to deliver copies of prospectuses or
                  preliminary prospectuses to Transgenomic shall be subject to
                  the receipt by Geron of reasonable assurances from
                  Transgenomic that Transgenomic will comply with the applicable
                  provisions of the Act and of such other securities or blue sky
                  laws as may be applicable in connection with any use of such
                  prospectuses or preliminary prospectuses.

           4.4    All fees, disbursements and out-of-pocket expenses and costs
                  incurred by Geron in connection with the preparation and
                  filing of the Registration Statement under Section 4.1 and in
                  complying with applicable securities and Blue Sky laws
                  (including, without limitation, all attorneys' fees of Geron)
                  shall be borne by Geron. Transgenomic shall bear the cost of
                  fees and expenses of Transgenomic's counsel.

           4.5    Geron will advise Transgenomic promptly after it shall receive
                  notice or obtain knowledge of the issuance of any stop order
                  by the Commission delaying or suspending the effectiveness of
                  the Registration Statement or of the initiation of any
                  proceeding for that purpose, and Geron will use its
                  commercially reasonable efforts to prevent the issuance of any
                  stop order or to obtain its withdrawal at the earliest
                  possible moment if such stop order should be issued.

           4.6    With a view to making available to Transgenomic the benefits
                  of Rule 144 (or its successor rule) and any other rule or
                  regulation of the Commission that may at the time permit
                  Transgenomic to sell the Shares to the public without
                  registration, Geron covenants and agrees to: (i) make and keep
                  public information available, as those terms are understood
                  and defined in Rule 144, until the earliest of (A) such date
                  as all of the Shares may be resold pursuant to Rule 144(k) or
                  any other rule of similar effect or (B) such date as all of
                  the Shares shall have been resold; and (ii) file with the
                  Commission in a timely manner all reports and other documents
                  required of Geron under the Act and under the Exchange Act of
                  1934, as amended.

           4.7    Transgenomic will cooperate with Geron in all respects in
                  connection with this Agreement, including timely supplying all
                  information reasonably requested by Geron (which shall include
                  all information regarding Transgenomic and proposed manner of
                  sale of the Shares required to be disclosed in any
                  Registration Statement) and executing and returning all
                  documents reasonably requested in connection with the
                  registration and sale of the Shares and entering into and
                  performing their obligations under any underwriting agreement,
                  if the offering is an underwritten offering, in usual and
                  customary form, with the managing underwriter or underwriters
                  of such underwritten offering. Nothing in this Agreement shall
                  obligate Transgenomic to consent to be named as an underwriter
                  in any Registration Statement.

    5. INDEMNIFICATION.

           5.1    Geron agrees to indemnify and hold harmless Transgenomic (and
                  each person, if any, who controls Transgenomic within the
                  meaning of Section 15 of the Act, and each officer and
                  director of Transgenomic) against any and all losses, claims,
                  damages or liabilities (or actions or proceedings in respect
                  thereof), joint or several, directly or indirectly based upon
                  or arising out of (i) any untrue statement or alleged untrue
                  statement of any material fact contained in the Registration
                  Statement, any preliminary prospectus, final prospectus or
                  summary prospectus contained therein or used in connection
                  with the offering of the Shares, or any amendment or
                  supplement thereto, or (ii) any omission or alleged omission

                                        3

<PAGE>

                  to state a material fact required to be stated therein or
                  necessary to make the statements therein not misleading; and
                  Geron will reimburse each such indemnified party for any legal
                  or any other expenses reasonably incurred by them in
                  connection with investigating, preparing, pursuing or
                  defending any such loss, claim, damage, liability, action or
                  proceeding, except insofar as any such loss, claim, damage,
                  liability, action, proceeding or expense (A) arises out of or
                  is based upon an untrue statement or alleged untrue statement
                  or omission or alleged omission made in the Registration
                  Statement, any such preliminary prospectus, final prospectus,
                  summary prospectus, amendment or supplement in reliance upon
                  and in conformity with written information furnished to Geron
                  by Transgenomic or such other person expressly for use in the
                  preparation thereof, (B) the failure of Transgenomic to comply
                  with its covenants and agreements contained in Sections 7.1 or
                  7.5.2 hereof or (C) any misstatement or omission in any
                  prospectus that is corrected in any subsequent prospectus that
                  was delivered to Transgenomic prior to the pertinent sale or
                  sales by Transgenomic. Such indemnity shall remain in full
                  force and effect, regardless of any investigation made by such
                  indemnified party and shall survive the transfer of the Shares
                  by Transgenomic.

           5.2    Transgenomic agrees to indemnify and hold harmless Geron (and
                  each person, if any, who controls Geron within the meaning of
                  Section 15 of the Act, each officer of Geron who signs the
                  Registration Statement and each director of Geron) from and
                  against losses, claims, damages or liabilities (or actions or
                  proceedings in respect thereof), joint or several, directly or
                  indirectly based upon or arising out of, (i) any failure of
                  Transgenomic to comply with the covenants and agreements
                  contained in Sections 7.1 and 7.5.2 hereof or (ii) any untrue
                  statement of a material fact contained in the Registration
                  Statement or any omission of a material fact required to be
                  stated in the Registration Statement or necessary in order to
                  make the statements in the Registration Statement not
                  misleading if such untrue statement or omission was made in
                  reliance upon and in conformity with written information
                  furnished to Geron by on behalf of Transgenomic specifically
                  for use in preparation of the Registration Statement;
                  provided, however, that Transgenomic shall not be liable in
                  any such case for (A) any untrue statement or omission in the
                  Registration Statement, prospectus, or other such document
                  which statement is corrected by Transgenomic and delivered to
                  Geron prior to the sale from which such loss occurred, (B) any
                  untrue statement or omission in any prospectus which is
                  corrected by Transgenomic in any subsequent prospectus, or
                  supplement or amendment thereto, and delivered to Geron prior
                  to the sale or sales from which a loss or liability arose, or
                  (C) any failure by Geron to fulfill any of its obligations
                  under Section 5.1 hereof.

           5.3    Promptly after receipt by any indemnified person of a notice
                  of a claim or the beginning of any action in respect of which
                  indemnity is to be sought against an indemnifying person
                  pursuant to this Section 5, such indemnified person shall
                  notify the indemnifying person in writing of such claim or of
                  the commencement of such action, but the omission to so notify
                  the indemnifying party will not relieve it from any liability
                  which it may have to any indemnified party under this Section
                  5 (except to the extent that such omission materially and
                  adversely affects the indemnifying party's ability to define
                  such action) or from any liability otherwise than under this
                  Section 5. Subject to the provisions hereinafter stated, in
                  case any such action shall be brought against an indemnified
                  person, the indemnifying person shall be entitled to
                  participate therein, and, to the extent that it shall elect by
                  written notice delivered to the indemnified party promptly
                  after receiving the aforesaid notice from such indemnified
                  party, shall be entitled to assume the defense thereof, with
                  counsel reasonably satisfactory to such indemnified person.
                  After notice from the indemnifying person to such indemnified
                  person of its election to assume the defense thereof, such
                  indemnifying person shall not be liable to such indemnified
                  person for any legal expense subsequently incurred by such
                  indemnified person in connection with the defense thereof,
                  provided, however, that if there exists or shall exist a
                  conflict of interest that would make inappropriate, in the
                  reasonable opinion of counsel to the indemnified person, for

                                       4

<PAGE>

                  the same counsel to represent both the indemnified person and
                  such indemnifying person or any affiliate or associate
                  thereof, the indemnified person shall be entitled to retain
                  its own counsel at the expense of such indemnifying person;
                  provided, however, that no indemnifying person shall be
                  responsible for the fees and expenses of more than on separate
                  counsel (together with appropriate local counsel) for all
                  indemnified parties. In no event shall any indemnifying person
                  be liable in respect to any amounts paid in settlement of any
                  action unless the indemnifying person shall have approved the
                  terms of such settlement. No indemnifying person shall,
                  without the prior written consent of the indemnified person,
                  effect any settlement of any pending or threatened proceeding
                  in respect of which any indemnified person is or could have
                  been a party and indemnification could have been sought
                  hereunder by such indemnified person, unless such settlement
                  includes an unconditional release of such indemnified person
                  from all liability on claims that are the subject matter of
                  such proceeding.

           5.4    The provisions of this Section 5 shall survive the termination
                  of this Agreement.

    6. REPRESENTATIONS AND ACKNOWLEDGEMENT OF GERON.

       Geron hereby represents, warrants and covenants to Transgenomic as
       follow:

           6.1    Organization, Good Standing and Qualification. Geron is a
                  corporation duly organized, validly existing and in good
                  standing under the laws of the State of Delaware and has all
                  requisite corporate power and authority to carry on its
                  business as now conducted and as presently proposed to be
                  conducted. Geron is duly qualified to transact business and is
                  in good standing as a foreign corporation in each jurisdiction
                  in which the failure to so qualify would have a material
                  adverse effect on its business or properties.

           6.2    Authorization. All corporate action on the party of Company,
                  its officers, directors and stockholders necessary for the
                  authorization, execution and delivery of this Agreement, the
                  performance of all obligations of Company hereunder and the
                  authorization, issuance and delivery of the Shares has been
                  taken or will be taken prior to the Closing, and this
                  Agreement, when executed and delivered will constitute valid
                  and legally binding obligations of Geron, enforceable against
                  Geron in accordance with their terms, except as limited by
                  applicable bankruptcy, insolvency, reorganization, moratorium,
                  fraudulent conveyance and other laws of general application
                  affecting enforcement of creditors' rights generally, as
                  limited by laws relating to the availability of specific
                  performance, injunctive relief or other equitable remedies.

           6.3    Valid Issuance of Common Stock. The Shares, when issued, sold
                  and delivered in accordance with the terms hereof for the
                  consideration expressed herein, will be duly and validly
                  authorized and issued, fully paid and nonassessable and free
                  of restrictions on transfer other than restrictions on
                  transfer under this Agreement and applicable state and federal
                  securities laws.

           6.4    Legal Proceedings and Orders. There is no action, suit,
                  proceeding or investigation pending or threatened against
                  Geron that questions the validity of this Agreement or the
                  right of Geron to enter into this Agreement or to consummate
                  this transactions contemplated hereby, nor is Geron aware of
                  any basis for any of the forgoing. Geron is neither a party
                  nor subject to the provisions of any order, writ, injunction,
                  judgment or decree of any court or government agency or
                  instrumentality that would affect the ability of Geron to
                  enter into this Agreement or to consummate the transactions
                  contemplated hereby.

    7. REPRESENTATIONS AND ACKNOWLEDGMENTS OF TRANSGENOMIC.

       Transgenomic hereby represents, warrants, acknowledges and agrees that:

                                       5

<PAGE>

           7.1    Investment. Transgenomic is acquiring the Shares for
                  Transgenomic's own account, and not directly or indirectly for
                  the account of any other person. Transgenomic is acquiring the
                  Shares for investment and not with a view to distribution or
                  resale thereof, except in compliance with the Act and any
                  applicable state law regulating securities.

           7.2    Access to Information. Transgenomic has consulted with its own
                  attorney, accountant, or investment advisor as Transgenomic
                  has deemed advisable with respect to the investment and has
                  determined its suitability for Transgenomic. Transgenomic has
                  had the opportunity to ask questions of, and to receive
                  answers from, appropriate executive officers of Geron with
                  respect to the terms and conditions of the transactions
                  contemplated hereby and with respect to the business, affairs,
                  financial condition and results of operations of Geron.
                  Transgenomic has had access to such financial and other
                  information as is necessary in order for Transgenomic to make
                  a fully informed decision as to investment in Geron, and has
                  had the opportunity to obtain any additional information
                  necessary to verify any of such information to which
                  Transgenomic has had access. Transgenomic acknowledges that
                  neither Geron nor any of its officers, directors, employees,
                  agents, representatives, or advisors have made any
                  representation or warranty other than those specifically
                  expressed herein.

           7.3    Business and Financial Expertise. Transgenomic further
                  represents and warrants that it has such business or financial
                  expertise as to be able to evaluate its investment in Geron
                  and purchase of the Shares.

           7.4    Speculative Investment. Transgenomic acknowledges that the
                  investment in Geron represented by the Shares is highly
                  speculative in nature and is subject to a high degree of risk
                  of loss in whole or in part; the amount of such investment is
                  within Transgenomic's risk capital means and is not so great
                  in relation to Transgenomic's total financial resources as
                  would jeopardize the personal financial needs of Transgenomic
                  in the event such investment were lost in whole or in part.

           7.5    Unregistered Securities.  Transgenomic acknowledges that:

                  7.5.1  Transgenomic must bear the economic risk of investment
                         for an indefinite period of time because the Shares
                         have not been registered under the Act and therefore
                         cannot and will not be sold unless they are
                         subsequently registered under the Act or an exemption
                         from such registration is available. Geron has made no
                         agreements, covenants or undertakings whatsoever to
                         register any of the Shares under the Act, except as
                         provided in Section 4 above. Geron has made no
                         representations, warranties or covenants whatsoever as
                         to whether any exemption from the Act, including,
                         without limitation, any exemption for limited sales in
                         routine brokers' transactions pursuant to Rule 144
                         under the Act, will become available and any such
                         exemption pursuant to Rule 144, if available at all,
                         will not be available unless: (i) a public trading
                         market then exists in Geron's common stock, (ii) Geron
                         has complied with the information requirements of Rule
                         144, and (iii) all other terms and conditions of Rule
                         144 have been satisfied.

                  7.5.2  Transfer of the Shares has not been registered or
                         qualified under any applicable state law regulating
                         securities and, therefore, the Shares cannot and will
                         not be sold unless they are subsequently registered or
                         qualified under any such act or an exemption therefrom
                         is available. Geron has made no agreements, covenants
                         or undertakings whatsoever to register or qualify any
                         of the Shares under any such act. Geron has made no
                         representations, warranties or covenants whatsoever as
                         to whether any exemption from any such act will become
                         available.

                                       6

<PAGE>

                  7.5.3  Transgenomic hereby certifies that it is an "Accredited
                         Investor" as that term is defined in Rule 501 under the
                         Act.

    8.     TAX ADVICE. Transgenomic acknowledges that Transgenomic has not
           relied and will not rely upon geron or Geron's counsel with respect
           to any tax consequences related to the ownership, purchase, or
           disposition of the shares. Transgenomic assumes full responsibility
           for all such consequences and for the preparation and filing of all
           tax returns and elections which may or must be filed in connection
           with the shares.

    9.     NOTICES. Any notice or other communication required or permitted
           hereunder shall be in writing and shall be deemed to have been duly
           given on the date of delivery if delivered personally or by
           facsimile, or one day, not including Saturdays, Sundays, or national
           holidays, after sending if sent by national overnight delivery
           service, or five days, not including Saturdays, Sundays, or national
           holidays, after mailing if mailed by first class united states mail,
           certified or registered with return receipt requested, postage
           prepaid, and addressed as follows:


                  To Geron at:                  Geron Corporation
                                                230 Constitution Drive
                                                Menlo Park, California  94025
                                                Attention: General Counsel
                                                Telephone:        (650) 473-7700
                                                Facsimile:        (650) 473-7750


                  To Transgenomic at:           Transgenomic, Inc.
                                                12325 Emmet Street
                                                Omaha, Nebraska 68164
                                                Attention:  Law Department
                                                Telephone:        (402) 452-5400
                                                Facsimile:        (402) 452-5447

    10.    BINDING EFFECT. This agreement shall be binding upon the heirs, legal
           representatives and successors of Geron and of Transgenomic;
           provided, however, that Transgenomic may not assign any rights or
           obligations under this agreement.

    11.    GOVERNING LAW. This agreement shall be governed by and construed in
           accordance with the laws of the State of California.

    12.    INVALID PROVISIONS. In the event that any provision of this agreement
           is found to be invalid or otherwise unenforceable by a court or other
           tribunal of competent jurisdiction, such invalidity or
           unenforceability shall not be construed as rendering any other
           provision contained herein invalid or unenforceable, and all such
           other provisions shall be given full force and effect to the same
           extent as though the invalid and unenforceable provision was not
           contained herein.

    13.    COUNTERPARTS. This agreement may be executed in any number of
           identical counterparts, each of which shall be deemed an original,
           but all of which together shall constitute one and the same
           instrument.

    14.    AMENDMENTS. This agreement or any provision hereof may be changed,
           waived, or terminated only by a statement in writing signed by the
           party against whom such change, waiver or termination is sought to be
           enforced.

    15.    FUTURE COOPERATION. Each of the parties hereto agrees to cooperate at
           all times from and after the date hereof with respect to all of the
           matters described herein, and to execute such further assignments,
           releases, assumptions, amendments of the agreement, notifications and
           other documents as may be reasonably requested for the purpose of
           giving effect to, or evidencing or giving notice of, the transactions
           contemplated by this agreement.

                                       7

<PAGE>

    16.    ENTIRE AGREEMENT. This agreement and the supply agreement, including
           addendum agreement no. 10 thereto, constitute the entire agreement of
           the parties pertaining to the shares and supersede all prior and
           contemporaneous agreements, representations, and understandings of
           the parties with respect thereto.

         IN WITNESS WHEREOF, the parties hereto have executed this Common Stock
Purchase Agreement as of the date first above written.

                                         Geron Corporation

                                         /s/ David L. Greenwood
                                         -------------------------------------
                                         By:    David L. Greenwood
                                         Title: Executive Vice President and
                                                Chief Financial Officer

                                         Transgenomic, Inc.

                                         /s/ Mitchell L. Murphy
                                         ---------------------------------------
                                         By:    Mitchell L. Murphy
                                         Title: Vice President, Secretary &
                                                Treasurer