To further investigate the mechanisms of TRAIL sensitization by GSK-3 inhibition, we employed PPC-1 prostate cancer cell overexpressing Bcl-2, Bcl-XL, and Mcl-1 to inhibit the mitochondrial pathway, or cytokine response modifier A (CrmA) to inhibit the death receptor pathway of caspase activation. This evidence concerns the gene MCL1 and prostate cancer.