TWEAK is a cytokine that belongs to the tumor necrosis factor (TNF) ligand family. This protein is a ligand for the FN14/TWEAKR receptor. It is widely expressed, has high constitutive expression in heart placenta, lung, muscle, kidney, pancreas, and HUVEC. This cytokine has overlapping signaling functions with TNF, but displays a much wider tissue distribution. TWEAK can induce apoptosis via multiple pathways of cell death in a cell type specific manner. This cytokine is also found to promote proliferation and migration of endothelial cells, and thus acts as a regulator of angiogenesis.