Atiprimod induces caspase activation in MCL cells. (A) Atiprimod-induced activation and cleavage of caspase-9, casapase-3, and PARP. As a control, anti-Fas mAb-induced caspase (-8) activation in Jurkat cells is shown. MCL cells were cultured with 2 μM atiprimod for different times. Jurkat cells were treated with 100 ng/mL anti-Fas mAb for 6 hours. Whole-cell lysates were subjected to Western blot analysis. Pan-caspase inhibitor Z-VAD or caspase-9 inhibitor Z-LEHD completely abrogated the cleavage of PARP (B), but had no effects on atiprimod-induced apoptosis in MCL cells (C). Arrows indicate cleaved (c) forms of caspases and PARP. Ati indicates atiprimod.