Caspase-8, a member of the caspase-family of proteases, plays a key role in mediating Fas (CD95) and TNF induced apoptosis. Caspase-8 is synthesized as inactive pro-enzyme and activation of the enzyme involves proteolytic cleavage that leads to the release of the active p18 and p10 subunits. Activated caspase-8 is able to cleave and activate downstream caspases, such as caspase-3, -6, -7 and a death agonist member of the Bcl-2/Bcl-xL family, Bid, leading to apoptosis.