Human CD95 (APO-1/Fas) Recombinant Protein, eBioscience?. CD95 (Fas, APO-1), a 46 kDa transmembrane glycoprotein, is a cell death receptor of the TNFR superfamily. Stimulation of CD95 results in aggregation of its intracellular death domains, formation of the death-inducing signaling complex (DISC) and activation of caspases. In type I cells caspase 3 is activated by high amounts of caspase 8 generated at the DISC, in type II cells low concentration of caspase 8 activates pathway leading to the release of cytochrome c from mitochondria and activation of caspase 3 by cytochom c. Besides its roles in induction of apoptosis, Fas also triggers pro-inflammatory cytokine responses.