Integrins are alpha/beta heterodimeric cell surface receptors that play a pivotal role in cell adhesion and migration, as well as in growth and survival. The integrin family contains at least 18 alpha and 8 beta subunits that form 24 known integrins having distinct tissue distribution and overlapping ligand specificities. Integrins not only transmit signals to cells in response to the extracellular environment (outside-in signaling), but also sense intracellular cues to alter their interaction with extracellular environment (inside-out signaling). The alphaVbeta5 integrin is expressed in various tissues and cell types, including endothelia, epithelia and fibroblasts. It plays a role in matrix adhesion to VN, FN, SPARC and bone sialoprotein and functions in the invasion of gliomas and metastatic carcinoma cells. alphaVbeta5 integrin plays a major role in growth-factor-induced tumor angiogenesis, where cooperative signaling by the alphaVbeta5 integrin and growth factors regulates endothelial cell proliferation and survival.
