Tumor necrosis factor receptor superfamily member 10A (TNFRSF10A) is also known as TNF-related apoptosis-inducing ligand receptor 1 (TRAIL-R1), Death receptor 4 (DR4), CD261 and APO2, which belongs to TNF superfamily. TRAILR1 / TNFRSF10A contains 1 death domain and 3 TNFR-Cys repeats. TNFRSF10A / DR4 is widely expressed and high levels are found in spleen, peripheral blood leukocytes, small intestine and thymus, but also in K-562 erythroleukemia cells, MCF-7 breast carcinoma cells and activated T-cells. APO2 / TNFRSF10A is receptor for the cytotoxic ligand TNFSF10 / TRAIL. The adapter molecule FADD recruits caspase-8 to the activated receptor. The resulting death-inducing signaling complex (DISC) performs caspase-8 proteolytic activation which initiates the subsequent cascade of caspases (aspartate-specific cysteine proteases) mediating apoptosis. TRAILR-1 / DR4 / CD261 promotes the activation of NF-kappa-B.