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                                                                Exhibit 10.31


                               STOCK PURCHASE AGREEMENT

     This Stock Purchase Agreement (the "Agreement") is entered into 
effective as of this 29th day of January, 1999, by and among SuperGen, Inc., 
a Delaware corporation (the "COMPANY") and Tako Ventures, LLC, a California 
limited liability company (the "PURCHASER").

                                      BACKGROUND

     A.   Pursuant to Section 5.1 of that certain Convertible Note, Option 
and Warrant Purchase Agreement dated as of June 17, 1997, by and among the 
Company, the Purchaser and Lawrence J. Ellison ("ELLISON") (the "ORIGINAL 
PURCHASE AGREEMENT"), the Purchaser has the right to purchase its pro rata 
share of securities to be issued by the Company (the "PRE-EMPTIVE RIGHT").

     B.   In connection with the Company's sale and issuance of 460,000 
shares of Common Stock to an institutional investor on December 23, 1998 
pursuant to the Common Stock Purchase Agreement dated as of November 23, 1998 
(the "NOVEMBER PURCHASE AGREEMENT"), the Purchaser desires to exercise its 
Pre-emptive Right and purchase 61,350 shares of the Company's Common Stock 
pursuant to this Agreement, and the Company and the Purchaser desire to 
resolve certain differences that have arisen between them as to the 
adjustments to be made pursuant to the antidilution provisions under Section 
1.2(b) of the Original Purchase Agreement as a result of the November 
Purchase Agreement.

     NOW THEREFORE, the parties agree as follows:

     1.   SALE AND PURCHASE OF SECURITIES.  On the terms and subject to the 
conditions set forth in this Agreement, the Company will issue and sell to 
the Purchaser, and the Purchaser will purchase 61,350 shares of the Company's 
Common Stock (the "SHARES") at a per share purchase price of approximately 
$6.52 for an aggregate purchase price of $400,002 (the "PURCHASE PRICE").

     2.   CLOSING.

          a.   The closing of the purchase and sale of the Shares (the 
"CLOSING") will be held at the office of Wilson Sonsini Goodrich & Rosati, 
Professional Corporation, 650 Page Mill Road, Palo Alto, California 
94304-1050 at 10:00 a.m. on January 29, 1999, or such other time or place as 
the parties may agree.

          b.   At the Closing, the representations and warranties of the 
parties set forth in Section 3 below shall be true and correct in all 
material respects.

          c.   At the Closing, (A) the Purchaser shall (i) pay the Purchase 
Price by wire transfer to the Company's account and (ii) deliver to the 
Company, for cancellation, exchange and reissuance in accordance with clause 
(B)(ii) of this subsection, the Series 2 Warrants heretofore issued to 
Purchaser to purchase an aggregate of seven hundred seventy-five thousand 
(775,000) shares of Common Stock, and (B) the Company shall (i) cause the 
transfer agent to deliver a 

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certificate evidencing the Shares in the name of the Purchaser (ii) shall 
deliver to Purchaser Series 1 Warrants to purchase an aggregate of seven 
hundred seventy-five thousand (775,000) shares of Common Stock, two hundred 
thirty thousand (230,000) of which shall be subject to an initial Warrant 
Exercise Price of ten dollars thirty-five cents ($10.35) per share and five 
hundred forty-five thousand (545,000) of which shall be subject to an initial 
Warrant Exercise Price of thirteen dollars and fifty cents ($13.50) per 
share, subject in each case to adjustment as set forth therein and in the 
Original Purchase Agreement and (iii) shall deliver to Purchaser a 
certificate evidencing 107,333 shares of Common Stock of the Company (the 
"ANTIDILUTION SHARES").  The certificates evidencing the Shares and the 
Antidilution Shares and the Series 1 Warrants issued hereunder shall bear the 
restrictive legends set forth in Section 5.11 of the Original Purchase 
Agreement.

     3.   REPRESENTATIONS AND WARRANTIES.  (a) In connection with the 
issuance and purchase of the Shares, the Series 1 Warrants and the 
Antidilution Shares, the Purchaser hereby represents and warrants to the 
Company as set forth in Section 4 of the Original Purchase Agreement 
(provided that any references therein to Option, Note, Warrants or Securities 
shall be deemed to refer solely to the Shares and the Antidilution Shares and 
the Series 1 Warrants issued hereunder, and the term "Agreement" shall refer 
to this Agreement), and (b) in connection with the issuance and purchase of 
the Shares, the Company hereby represents and warrants to the Purchaser that 
except as set forth on a separate disclosure letter delivered to the 
Purchaser as of the date of this Agreement, the representations and 
warranties set forth in Section 3.1 of the November Purchase Agreement are 
true and correct in all material respects as of the date of this Agreement 
(provided that the term "Agreement" shall refer to this Agreement and the 
term "Shares" shall refer to the Shares, the Antidilution Shares and the 
Series 1 Warrants issued hereunder and shares of Common Stock issued upon 
exercise of the Series 1 Warrants).  The Purchaser acknowledges and agrees 
that the issuance of the Shares in accordance with this Agreement satisfies 
its Pre-emptive Right with respect to the November Purchase Agreement and 
that the issuance of the Series 1 Warrants and the Antidilution Shares in 
accordance with this Agreement satisfies Purchaser's antidilution rights 
under Section 1.2(b) of the Original Purchase Agreement with respect to the 
November Purchase Agreement.

     4.   MISCELLANEOUS.  This Agreement is governed by the laws of the state 
of California.  This Agreement may not be amended nor any provision waived 
except in writing signed by both parties.  This Agreement represents the 
entire agreement between the parties regarding subject matter hereof.  This 
Agreement may be executed in counterparts, each of which shall be deemed an 
original and all of which shall constitute one instrument.

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     IN WITNESS WHEREOF, the parties execute this Agreement as of the date 
first written above.

                                   SuperGen, Inc.


                                   /s/ Dr. Joseph Rubinfeld
                                  -------------------------------------
                                   Dr. Joseph Rubinfeld, CEO



                                   Tako Ventures, LLC
                                   By:  CEPHALOPOD CORPORATION,
                                        MEMBER


                                   /s/ Philip Simon                    
                                  -------------------------------------
                                   Philip Simon, PRESIDENT
                                   CEPHALOPOD CORPORATION

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