IL-1β (Interleukin-1 Beta) is an inflammatory cytokine that might modulate angiogenesis by directly interacting with vascular endothelial cells or enhancing the production of proangiogenic factors via paracrine control. IL-1β stimulates endothelial cell migration and proliferation, adhesion-molecule expression, inflammatory mediator production, and leukocyte recruitment. IL-1β is required for tumor growth, metastasis, and angiogenesis in several animal models.