Effect of caspase 3 inhibition on apoptotic DNA fragmentation in response to C₂-ceramide. Log-phase Molt-4 cells were treated as follows: (A) 0.2% dimethyl sulfoxide (DMSO) for 17 hours; (B) 20 μmol/L C₂-ceramide for 17 hours; (C) 50 μmol/L Ac-DEVD-CHO for 35 hours; (D) 18-hour preincubation with 50 μmol/L Ac-DEVD-CHO followed by 17 hours coincubation with 20 μmol/L C₂-ceramide. Cells were harvested and prepared for FACS analysis as described in Materials and Methods. This data is a representative experiment from three separate determinations.