
<TABLE> <S> <C>

<PAGE>
<ARTICLE> 5
       
<S>                             <C>
<PERIOD-TYPE>                   6-MOS
<FISCAL-YEAR-END>                          DEC-31-1998
<PERIOD-END>                               JUN-30-1998
<CASH>                                      12,864,589
<SECURITIES>                                10,430,726
<RECEIVABLES>                                        0
<ALLOWANCES>                                         0
<INVENTORY>                                          0
<CURRENT-ASSETS>                            24,795,359
<PP&E>                                      15,495,443
<DEPRECIATION>                               7,148,545
<TOTAL-ASSETS>                              39,634,956
<CURRENT-LIABILITIES>                        7,151,333
<BONDS>                                      4,655,000
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                       176,905
<OTHER-SE>                                  22,354,733
<TOTAL-LIABILITY-AND-EQUITY>                39,634,956
<SALES>                                              0
<TOTAL-REVENUES>                             3,749,563
<CGS>                                                0
<TOTAL-COSTS>                                        0
<OTHER-EXPENSES>                            11,828,274
<LOSS-PROVISION>                                     0
<INTEREST-EXPENSE>                             233,695
<INCOME-PRETAX>                            (7,566,910)
<INCOME-TAX>                                         0
<INCOME-CONTINUING>                        (7,566,910)
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                               (7,566,910)
<EPS-PRIMARY>                                    (.42)
<EPS-DILUTED>                                    (.42)
        

</TABLE>
