The protein encoded by this gene is a cytokine that belongs to the tumor necrosis factor (TNF) ligand family. This protein is abundantly expressed in endothelial cells, but is not expressed in either B or T cells. The expression of this protein is inducible by TNF and IL-1 alpha. This cytokine is a ligand for receptor TNFRSF25 and decoy receptor TNFRSF21/DR6. It can activate NF-kappaB and MAP kinases, and acts as an autocrine factor to induce apoptosis in endothelial cells. This cytokine is also found to inhibit endothelial cell proliferation, and thus may function as an angiogenesis inhibitor. Two transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Feb 2011],function:Receptor for TNFRSF25 and TNFRSF6B. Mediates activation of NF-kappa-B. Inhibits vascular endothelial growth and angiogenesis (in vitro). Promotes activation of caspases and apoptosis.,induction:Up-regulated by IL-1-alpha and TNF-alpha.,similarity:Belongs to the tumor necrosis factor family.,subunit:Homotrimer.,tissue specificity:Specifically expressed in endothelial cells. Detected in monocytes, placenta, lung, liver, kidney, skeletal muscle, pancreas, spleen, prostate, small intestine and colon.,