Induction of cIAP-1 degradation, cleavage of PARP and processing of caspase-3 by compounds 1, 2, 4 and 6 in the MDA-MB-231 cell line. Cells were treated with different concentrations of Smac mimetics for 24 hours and levels of cIAP-1, cleaved PAPR (CL PARP), cleaved caspase-3 (CL C3) were probed by Western blot.