<TABLE> <S> <C>

<PAGE>
<ARTICLE> 5
<RESTATED> 
       
<S>                             <C>                     <C>                     <C>                     <C>
<PERIOD-TYPE>                   YEAR                   YEAR                   9-MOS                   9-MOS
<FISCAL-YEAR-END>                          DEC-31-1997             DEC-31-1996             DEC-31-1997             DEC-31-1996
<PERIOD-START>                             JAN-01-1997             JAN-01-1996             JAN-01-1997             JAN-01-1996
<PERIOD-END>                               DEC-31-1997             DEC-31-1996             SEP-30-1997             SEP-30-1996
<CASH>                                      26,810,777               5,465,471               5,160,698                       0
<SECURITIES>                                 6,428,374               6,742,718               8,054,492                       0
<RECEIVABLES>                                2,046,641                       0                       0                0
<ALLOWANCES>                                         0                       0                       0                       0
<INVENTORY>                                    566,989                       0                       0                       0
<CURRENT-ASSETS>                            36,539,724              12,678,505              13,749,381                       0
<PP&E>                                       6,438,098               3,732,451               5,789,937                       0
<DEPRECIATION>                               3,727,585               2,598,662               3,438,419                       0
<TOTAL-ASSETS>                              39,606,413              14,089,493              16,491,213                       0
<CURRENT-LIABILITIES>                        5,672,258               3,675,859               4,495,479                       0
<BONDS>                                              0                       0                       0                       0
<PREFERRED-MANDATORY>                                0                       0                       0                       0
<PREFERRED>                                          0                 243,452                 243,542                       0
<COMMON>                                       128,686                   7,233                  22,280                       0
<OTHER-SE>                                  32,383,486               9,848,342              10,522,616                       0
<TOTAL-LIABILITY-AND-EQUITY>                39,606,413              14,089,493              16,491,213                       0
<SALES>                                              0                       0                       0                       0
<TOTAL-REVENUES>                            17,489,264               3,098,289              12,831,123               2,349,328
<CGS>                                                0                       0                       0                       0
<TOTAL-COSTS>                                        0                       0                       0                       0
<OTHER-EXPENSES>                            18,769,928              13,854,853              13,035,205              10,252,810
<LOSS-PROVISION>                                     0                       0                       0                       0
<INTEREST-EXPENSE>                             129,022                  92,270                  80,920                  71,614
<INCOME-PRETAX>                              (441,545)            (10,158,089)                 445,831             (7,459,638)
<INCOME-TAX>                                         0                       0                       0                       0
<INCOME-CONTINUING>                          (441,545)            (10,158,089)                 445,831             (7,459,638)
<DISCONTINUED>                                       0                       0                       0                       0
<EXTRAORDINARY>                                      0                       0                       0                       0
<CHANGES>                                            0                       0                       0                       0
<NET-INCOME>                                 (441,545)            (10,158,089)                 445,831             (7,459,638)
<EPS-PRIMARY>                                   $(.04)                 $(1.26)                    $.04                  $(.95)
<EPS-DILUTED>                                   $(.04)                 $(1.26)                    $.04                  $(.95)
        

</TABLE>