Focal adhesion kinase in integrin-mediated signaling.

Integrins serve as adhesion receptors for extracellular matrix proteins and also transduce biochemical signals into the cell. These signaling events regulate such cellular processes as proliferation, apoptosis, migration and spreading. Focal adhesion kinase (FAK) is an important protein tyrosine kinase which mediates several integrin signaling pathways. Putative mechanisms of integrin-mediated FAK activation and localization to focal adhesions are discussed here. FAK interacts with a number of signaling and cytoskeletal proteins, including Src, phosphatidylinositol 3-kinase, Grb2, p130Cas and paxillin. Both the mechanisms and outcomes of these interactions are also presented. Finally, FAK's roles in the regulation of several integrin-mediated cellular events are discussed, including the promotion of cell migration, proliferation and spreading, and the prevention of cell apoptosis.