TL1A, also known as TNF ligand-related molecule 1, vascular endothelial growth inhibitor, and TNF ligand superfamily member 15, is a type II membrane protein with a predicted molecular weight of 28 kD. TL1A can also be found as a secreted protein as a result of proteolytic cleavage, with a reported molecular weight of 32 kD. TL1A is a ligand for DR3 and DcR3 and is highly expressed in endothelial cells. TL1A expression has also been observed in kidney, lung, prostate, placenta, and liver. Expression of TL1A is inducible with TNF and IL-1alpha (but not IFN-gamma). TL1A acts to inhibit endothelial cell growth and has been reported to induce endothelial cell apoptosis and inhibit neovascularization in tumors. In lymphocytes, TL1A has been shown to enhance IL-2 receptor alpha and beta expression and increase IL-2 induced proliferation and secretion of IFN-gamma and GM-CSF. The 6E6 monoclonal antibody recognizes human TL1A and has been shown to be useful for immunoprecipitation and Western blot. In addition, the 6E6 antibody has been reported to enhance endothelial cell proliferation, motility and migration, and induce the formation of tube networks.