Fas Receptor and Fas Ligand (FasL) belong to the TNF superfamily and are type I and type II transmembrane proteins, respectively. Binding of FasL to Fas triggers apoptosis in Fas-bearing cells. The mechanism of apoptosis involves recruitment of pro-caspase 8 through an adaptor molecule called FADD followed by processing of the pro-enzyme to active forms. These active caspases then cleave various cellular substrates leading to the eventual cell death. sFasR is capable of inhibiting FasL-induced apoptosis by acting as a decoy receptor that serves as a sink for FasL.