CASP9 and melanoma: Enhanced processing of the major effector caspases (caspase-3, caspase-7, caspase-8 and caspase-9) to their active forms and cleavage of PARP (a target of activated effector caspases) was observed at 48 hours following treatment of the A375 human melanoma cells with ixazomib and bortezomib (Figure 8A).