Fas/Apo-1/CD95 is a cell surface type-I membrane glycoprotein with an apparent molecular weight of 44 kDa on SDS-PAGE. Fas is a member of the TNFR family that includes TNFR1, TNFR2, CD27, CD30, and CD40. Binding of Fas-ligand (FasL) to Fas or crosslinking of Fas by anti-Fas monoclonal antibodies leads to apoptosis in Fas expressing cells. Both Fas and TNF-R contain the 70 amino acids cytoplasmic
