The effects of C93 on cell cycle progression and induction of apoptosis in JAR and JEG3 cell lines. A: DNA flow cytometry analysis shows that the cell cycle distribution of choriocarcinoma cells is not altered after C93 treatment. In contrast, the late apoptotic cells, as defined by the subG1 fraction, significantly increase 48 hours after C93 treatment. B: The percentage of early apoptotic cells as detected by positive Annexin V staining increase in a time-dependent manner. DMSO was used as the negative control. C: Western blot analysis demonstrates the cleavage of caspase-3, caspase-9, and PARP (asterisks) is detected as early as 4 hours after C93 treatment in both cell lines. The upper bands in both caspase-9 and PARP represent the uncleaved forms of the proteins. Glyceraldehyde-3-phosphate dehydrogenase was used as the loading control.