A protein on cell surfaces that anchors cells to their surroundings and transmits signals between the outside and inside of the cell.Integrins are heterodimeric transmembrane receptors (α and β subunits) that mediate cell-extracellular matrix adhesion and bidirectional signaling. They regulate cell migration, proliferation, survival, and differentiation. The αvβ3 and αvβ5 integrins are overexpressed on tumor vasculature and promote angiogenesis. Cilengitide (cyclic RGD pentapeptide) was designed to inhibit αvβ3/αvβ5 integrins to block tumor angiogenesis. Eptifibatide targets the αIIbβ3 integrin on platelets to prevent platelet aggregation in acute coronary syndromes.