EXHIBIT 4.2 

COMMON STOCK PURCHASE AGREEMENT


     THIS
COMMON STOCK PURCHASE AGREEMENT (“Agreement”) is made and entered into as of
January 27, 2009 (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 MPI Research,
Inc., a Michigan corporation having its principal place of business at 54943
North Main Street, Mattawan, MI 49071 (“MPI”). 

	      	A.	      	Geron and MPI are the parties to
      that certain Master Agreement dated as of December 12, 2003 (the
      “Master Agreement”), and related Services Agreement Addenda under which
      Geron and MPI have agreed that MPI will perform certain services on behalf
      of Geron on the terms set forth therein.
		 
		B.		Pursuant to the third amendment
      to the Master Agreement, dated August 13, 2008 (“Amendment No. 3”) and the
      fourth amendment to the Master Agreement, dated January 22, 2009
      (“Amendment No. 4”), Geron may pay for the price of such services by
      delivery of shares of Geron’s Common Stock (the “Shares”).
		 
		C.		Geron has elected to make payment
      for such services performed pursuant to Amendment No. 4 through the
      delivery of Shares, pursuant to the terms and conditions of Amendment No.
      4 and this Agreement.


THE PARTIES AGREE AS FOLLOWS:


	1.		ISSUANCE OF SHARES;
      ADJUSTMENTS.
	 
	 	      	1.1.	      	As payment of the price
      specified in Amendment No. 4, Geron will issue and deliver certificates
      for 69,290 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 Geron shall make commercially reasonable efforts to accomplish
      the Closing no later than five (5) business days after the Effective Date
      hereof (the “Closing Date”). At the Closing, Geron shall deliver to MPI
      one or more certificates representing all of the Shares, which Shares
      shall be issued in the name of MPI or its designee and in such
      denominations as MPI shall specify.
	 
	 		2.2.		Geron’s obligations to
      issue and deliver the stock certificate(s) representing the Shares to MPI
      at the Closing shall be subject to the following conditions, which may be
      waived by Geron:
	 
	 		 		2.2.1.   
        	the covenants and obligations
      that MPI 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 MPI herein shall be true and correct in all material
      respects as of the Closing Date.
	 
	 		2.3.		MPI’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 MPI:
	 
	 		 		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;







	 	     		    	2.3.2.		Geron shall have available under
      its Certificate of Incorporation sufficient authorized shares of Common
      Stock to issue the Shares to MPI; and
	 
	 		 		2.3.3.	      	the representation and
      warranties made by 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. MPI 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 MPI
      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 JANUARY 27,
      2009. A COPY OF THE AGREEMENT CAN BE OBTAINED FROM THE SECRETARY OF
      GERON.”
	 
	 		3.2.		Limits on
      Sales. MPI agrees that if it decides to
      resell some or all of the Shares, it will do so only through orderly sales
      executed through a top-tier brokerage house, and in an appropriate manner
      based upon whether the shares are registered or unregistered,
      i.e., on the Nasdaq Global Market or in a Rule 144A compliant
      transaction. MPI further agrees that it will not engage in short selling
      with respect to the Stock.
	 
	4.		REGISTRATION RIGHTS
	 
	 		4.1.		Geron agrees
      to make commercially reasonable efforts to file with the Securities and
      Exchange Commission (the “Commission”) within ten (10)
      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 MPI. Geron agrees to diligently
      pursue making the Registration Statement effective. Geron will notify MPI
      of the effectiveness of the Registration Statement within one (1) business
      day of receiving notice from the Commission.
	 
	 		4.2.		Geron will
      make commercially reasonable efforts to 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 MPI receives an opinion of
      counsel from Geron, which counsel shall be reasonably acceptable to MPI,
      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 or any similar provision then in effect
      under the Act in the opinion of counsel to Geron, which counsel shall be
      reasonably acceptable to MPI.
	 
	 		4.3.		Geron, at
      its expense, shall furnish to MPI 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
      MPI may reasonably request, in order to facilitate the public sale or
      other disposition of all or any of the Shares by MPI, provided, however,
      that the obligation of Geron to deliver copies of prospectuses or
      preliminary prospectuses to MPI shall be subject to the receipt by Geron
      of reasonable assurances from MPI that MPI 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.


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	 	      	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. MPI shall bear the cost of fees and expenses of MPI’s
      counsel.
	 
	 		4.5.		Geron will advise MPI
      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 MPI the benefits of Rule 144 (or its successor rule) and any
      other rule or regulation of the Commission that may at the time permit MPI
      to sell the Shares to the public without registration, Geron covenants and
      agrees to make commercially reasonable efforts 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 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 Securities Exchange Act of 1934, as
      amended (the “Exchange
      Act”).
	 
	 		4.7.		MPI 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 MPI 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 MPI to consent to be named as an
      underwriter in any Registration Statement.
	 
	5.		INDEMNIFICATION.
	 
	 		5.1.	      	Geron agrees to
      indemnify and hold harmless MPI (and each person, if any, who controls MPI
      within the meaning of Section 15 of the Act, and each officer and director
      of MPI) 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 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 MPI or such other person expressly for use in the
      preparation thereof, (B) the failure of MPI 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 MPI prior to the pertinent
      sale or sales by MPI. 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
MPI.


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	 	     	5.2.	      	MPI 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 MPI 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 MPI specifically for use in preparation of the
      Registration Statement; provided, however, that MPI 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 MPI 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 MPI 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 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 one 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 MPI as follows:
	 
	 		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.


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	 	      	6.2.	     	Authorization. All corporate
      action on the party of Geron, its officers, directors and stockholders
      necessary for the authorization, execution and delivery of this Agreement,
      the performance of all obligations of Geron 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 MPI.
	 
	 		MPI hereby
      represents, warrants, acknowledges and agrees that:
	 
	 		7.1.		Investment. MPI is acquiring the
      Shares for MPI’s own account, and not directly or indirectly for the
      account of any other person. MPI 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. MPI has consulted with its
      own attorney, accountant, or investment advisor as MPI has deemed
      advisable with respect to the investment and has determined its
      suitability for MPI. MPI 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. MPI has had access to such financial and
      other information as is necessary in order for MPI 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 MPI has had access. MPI 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. MPI 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. MPI 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 MPI’s risk capital means and
      is not so great in relation to MPI’s total financial resources as would
      jeopardize the personal financial needs of MPI in the event such
      investment were lost in whole or in part.


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			7.5.		Unregistered
      Securities. MPI acknowledges
  that:
						      	 
	 	      		     	7.5.1.		MPI 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.
	 
	 				7.5.3.	 	MPI hereby certifies that it
      is an “Accredited
      Investor” as that term is defined in Rule 501 under the
    Act.
	 
	8.		TAX
      ADVICE. MPI acknowledges that MPI 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. MPI 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: Senior Director, Legal  
	  		Telephone:  	(650)
      473-7700  
	  		Facsimile:  	(650)
      473-7750  
	  
	  
	To MPI
      at:  		MPI
      Research, Inc.  
	  		54943
      North Main Street  
	  		Mattawan, MI 49071  
	  		Telephone: 269.668.3336  
	  		Facsimile: 269.668.4151  




	10.	      	BINDING
      EFFECT. This Agreement shall be binding
      upon the heirs, legal representatives and successors of Geron and of MPI;
      provided, however, that MPI 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.


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	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.
	 
	16.		ENTIRE
      AGREEMENT. This Agreement and the
      Master Agreement as amended, including Amendment No. 4 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  
		 
		  
		MPI
      Research, Inc.  
		 
		   
		/s/ William Harrison  	 
		By: 
    	William Harrison  
		Title:      	President and Chief Operating Officer 




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