Tumor necrosis factor‑associated apoptosis‑inducing ligand (TRAIL) is a type II membrane protein of the tumor necrosis factor (TNF) family members, moreover, expressed in many adult tissues including the thymus, prostate, colon, ovary and lung. TRAIL is a 19kDa protein containing 281 residues. TRAIL to induce apoptosis in human breast carcinoma cells (MCF7) and human epitheloid carcinoma (HeLa) cell lines, by activate two death receptors of DR4 and DR5 or two decoy receptors DcR1 and DcR2.