TNF-Related Apoptosis-Inducing Ligand (TRAIL) is produced by a wide variety of cell types and is shown to be a cytotoxic Protein that induces apoptosis in tumor cells through activation of the death receptors, DR4 and DR5. TRAIL is active on cells. Recombinant TRAIL is a non-glycosylated Protein, containing the 168 amino acid extracellular portion of TRAIL that is homologous to TNF. It has a molecular weight of 19.5 kDa.