TRAIL (TNF-related apoptosis-inducing ligand), a member of the TNF ligand family, is a type II membrane protein and expressed in a variety of human tissues. Two death domains containing receptors DR4 and DR5 have been identified as the receptors for TRAIL and two decoy receptors designated DcR1 and DcR2 inhibit TRAIL function. The multiple receptors sμggest a complex role for regulation of signaling by the cytokine. TRAIL induces apoptosis and NF-kB activation in many tissues and cells.