TL-1A belongs to the TNF superfamily of ligands. It is specially expressed in endothelial cells, and is detected in the placenta, lung, kidney, skeletal muscle, pancreas, small intestine and colon. TL-1A inhibits endothelial cell proliferation and angiogenesis. It has been proved to promote NF-κB activation, caspase activity, and apoptosis in responding cell lines. TL-1Acan bind with TNFRSF25/DR3 receptor and a decoy receptor TNFRSF21/DR6.