CASP8 and prostate carcinoma: Thus, in the present study, the underlying apoptotic mechanism of EP was investigated in DU 145 prostate cancer cells targeting extrinsic apoptosis via DR 5 signaling using MTT assay, cell cycle analysis, TUNEL assay, western blotting and inhibitor study using caspase 8 inhibitor Z-IETD-FMK and siRNA transfection of DR 5.