<TABLE> <S> <C>

<PAGE>
<ARTICLE> 5
<LEGEND>
This schedule contains summary financial information extracted from the
condensed balance sheets of March 31, 1996, June 30, 1996,
September 30, 1996, and December 31, 1996 and the condensed consolidated
statements of operations for the three months, six months, nine months and
year then ended.
</LEGEND>
<RESTATED> 
       
<S>                             <C>                     <C>                     <C>                     <C>
<PERIOD-TYPE>                   3-MOS                   6-MOS                   9-MOS                   YEAR
<FISCAL-YEAR-END>                          DEC-31-1996             DEC-31-1996             DEC-31-1996             DEC-31-1996
<PERIOD-START>                             JAN-01-1996             JAN-01-1996             JAN-01-1996             JAN-01-1996
<PERIOD-END>                               MAR-31-1996             JUN-30-1996             SEP-30-1996             DEC-31-1996
<CASH>                                       6,167,920              36,697,960              15,896,560               6,563,957
<SECURITIES>                                         0                       0              17,632,073              13,001,472
<RECEIVABLES>                                   24,168                       0                 150,841                       0
<ALLOWANCES>                                         0                       0                       0                       0
<INVENTORY>                                          0                       0                       0                       0
<CURRENT-ASSETS>                             6,565,609              37,649,304              34,438,493              20,652,945
<PP&E>                                       3,670,891               3,709,803               3,737,861               3,764,896
<DEPRECIATION>                               1,986,592               2,153,520               2,315,701               2,479,361
<TOTAL-ASSETS>                               8,407,384              39,288,557              35,935,326              32,315,635
<CURRENT-LIABILITIES>                        1,542,264               4,759,792               3,836,185               2,864,953
<BONDS>                                              0                       0                       0                       0
<PREFERRED-MANDATORY>                       36,186,820                       0                       0                       0
<PREFERRED>                                          0                       0                       0                       0
<COMMON>                                         1,266                  85,487                  85,489                  85,589
<OTHER-SE>                                   1,230,343              65,256,492              65,256,995              65,285,038
<TOTAL-LIABILITY-AND-EQUITY>                 8,407,384              39,288,557              35,935,326              32,315,635
<SALES>                                              0                       0                       0                       0
<TOTAL-REVENUES>                             2,075,697               5,631,012               7,374,345               9,046,143
<CGS>                                                0                       0                       0                       0
<TOTAL-COSTS>                                3,063,644               6,777,397              10,844,444              15,083,251
<OTHER-EXPENSES>                                     0                       0                       0                       0
<LOSS-PROVISION>                                     0                       0                       0                       0
<INTEREST-EXPENSE>                              51,208                  82,781                 110,557                 134,608
<INCOME-PRETAX>                              (987,947)             (1,146,385)             (3,470,099)             (6,037,108)
<INCOME-TAX>                                         0                       0                       0                       0
<INCOME-CONTINUING>                          (984,947)             (1,146,385)             (3,470,099)             (6,037,108)
<DISCONTINUED>                                       0                       0                       0                       0
<EXTRAORDINARY>                                      0                       0                       0                       0
<CHANGES>                                            0                       0                       0                       0
<NET-INCOME>                                 (987,947)             (1,146,385)             (3,470,099)             (6,037,108)
<EPS-PRIMARY>                                   (7.80)                  (0.44)                  (0.76)                  (1.08)
<EPS-DILUTED>                                   (7.80)                  (0.44)                  (0.76)                  (1.08)
        

</TABLE>