<TABLE> <S> <C>

<PAGE>
<ARTICLE> 5
       
<S>                             <C>                     <C>                     <C>                     <C>
<PERIOD-TYPE>                   3-MOS                   3-MOS                   6-MOS                   6-MOS
<FISCAL-YEAR-END>                          DEC-31-1997             DEC-31-1998             DEC-31-1997             DEC-31-1998
<PERIOD-START>                             APR-01-1997             APR-01-1998             JAN-01-1997             JAN-01-1998
<PERIOD-END>                               JUN-30-1997             JUN-30-1998             JUN-30-1997             JUN-30-1998
<CASH>                                               0              11,121,114                       0                       0
<SECURITIES>                                         0              19,244,306                       0                       0
<RECEIVABLES>                                        0               1,010,327                       0                       0
<ALLOWANCES>                                         0                       0                       0                       0
<INVENTORY>                                          0               1,175,655                       0                       0
<CURRENT-ASSETS>                                     0              32,551,402                       0                       0
<PP&E>                                               0               6,940,972                       0                       0
<DEPRECIATION>                                       0               4,270,560                       0                       0
<TOTAL-ASSETS>                                       0              35,610,765                       0                       0
<CURRENT-LIABILITIES>                                0               4,743,485                       0                       0
<BONDS>                                              0                       0                       0                       0
<PREFERRED-MANDATORY>                                0                       0                       0                       0
<PREFERRED>                                          0                       0                       0                       0
<COMMON>                                             0                 133,021                       0                       0
<OTHER-SE>                                           0              29,361,204                       0                       0
<TOTAL-LIABILITY-AND-EQUITY>                         0              35,610,765                       0                       0
<SALES>                                              0                       0                       0                       0
<TOTAL-REVENUES>                             1,950,333               1,569,603              10,854,562              3,510,4300
<CGS>                                                0                       0                       0                       0
<TOTAL-COSTS>                                        0                 822,373                       0               1,552,363
<OTHER-EXPENSES>                             4,365,584               5,046,906               8,388,390               9,939,570
<LOSS-PROVISION>                                     0                       0                       0                       0
<INTEREST-EXPENSE>                              22,551                  53,358                  42,040                 107,473
<INCOME-PRETAX>                             (2,211,901)             (3,905,986)               2,886,084             (7,134,957)
<INCOME-TAX>                                         0                       0                       0                       0
<INCOME-CONTINUING>                        (2,211,901)             (3,905,986)               2,886,084             (7,134,957)
<DISCONTINUED>                                       0                       0                       0                       0
<EXTRAORDINARY>                                      0                       0                       0                       0
<CHANGES>                                            0                       0                       0                       0
<NET-INCOME>                               (2,211,901)             (3,905,986)               2,886,044             (7,134,957)
<EPS-PRIMARY>                                   (0.21)                  (0.29)                    0.28                  (0.54)
<EPS-DILUTED>                                   (0.21)                  (0.29)                    0.28                  (0.54)
        

</TABLE>