tumor necrosis factor-like weak inducer of apoptosis (TWEAK) was discovered in 1997. The protein encoded by the TWEAK gene is a cytokine in the tumor necrosis factor (TNF) ligand family. White cells (including human resting and activated monocytes, dendritic cells, and natural killer cells) are the main source of TWEAK. TWEAK can induce apoptosis through a variety of pathways, depending on the cell type, and can also promote the proliferation and migration of endothelial cells, thus playing a role in regulating angiogenesis. In chronic injury, over-activated TWEAK pathways can promote pathological tissue changes, including chronic inflammation, fibrosis, and angiogenesis.