Z-VAD-FMK (carbobenzoxy-valyl-alanyl-aspartyl-[O-methyl]-fluoromethylketone) is a cell-permeant pan caspase inhibitor that irreversibly binds to the catalytic site of caspase proteases and can inhibit induction of apoptosis. For inhibition of apoptosis, Z-VAD-FMK should be added at the same time that apoptosis is induced. Z-VAD-FMK is provided at 20mM in DMSO for convenient addition to cell culture or extracts. The peptide is O-methylated in the P1 position on aspartic acid, providing enhanced stability and increased cell permeability. The suggested concentration for use in the anti-Fas mAb-treated Jurkat cell culture model system is 20uM.|