Inhibition of caspase-8 and -3 and PARP cleavage by DEVD and IETD. Day-6 cells were cultured in medium with or without 500 U/mL of IFNγ for 96 hours in the presence or absence of DEVD-fmk and IETD-fmk at 40 μmol/L. The cell protein lysates were electrphoresed using a 13% acrylamide gel to separate caspase-8 and -3 and an 8% gel for PARP.