Interleukin-1 alpha (IL-1α), a potent pro-inflammatory cytokine belonging to the IL-1 family. Unlike its relative IL-1β, which is primarily secreted, IL-1α exists in both a precursor form anchored to the cell membrane and a released mature form. It acts as a key "alarmin" or damage-associated molecular pattern (DAMP). IL-1α is rapidly released from cells undergoing necrosis (a common feature in inflammatory diseases and tumors) and signals through the same receptor (IL-1R1) as IL-1β. Its signaling drives the production of other inflammatory mediators (e.g., IL-6, IL-8, prostaglandins), recruits neutrophils, and promotes angiogenesis.