Integrins are transmembrane glycoprotein receptors that mediate cell-matrix or cell-cell adhesion, and transduce signals that regulate gene expression and cell growth. They are heterodimeric molecules consisting of noncovalently linked alpha and beta subunits. Different combinations of alpha and beta polypeptides form complexes that vary in their ligand-binding specificities. Both alpha and beta subunits display a cytoplasmic domain that interacts with the cytoskeleton (and possibly signaling molecules), a transmembrane region, and a large extracellular domain that interacts with the extracellular matrix. (from OMIM 147557)