Human TRAIL (TNF-Related Apoptosis Inducing Ligand)，also called Apo2 Ligand (Apo2L)，is a cytotoxic protein that activates rapid apoptosis in tumor cells，but not at normal cells. Human TRAIL/Apo2L is a single polypeptide chain containing 168 amino acids and has a molecular mass of 19.6 kDa.
