Integrins in morphogenesis and signaling.

Integrins are a family of heterodimeric transmembrane receptors that provide a physical and biochemical bridge between components of the extracellular matrix and the intracellular physiological environment. Binding of integrins to their ligands results in the formation of cytoplasmic multi-protein assemblies composed of both cytoskeletal and signaling molecules. The composition and activity of these assemblies is regulated by the nature of integrin-ligand interactions, as well as by intracellular regulators that include tyrosine kinases and phosphatases, PKC, and small GTPases. Integrin-mediated cellular physiological responses include the activation of signal transduction, cytoskeletal rearrangements, and co-regulation of growth factor activities. These responses, combined with integrin-mediated cell adhesion, play a major role in tissue morphogenesis and developmental processes.