Fibroblast growth factors, their receptors and signaling

Fibroblast growth factors (FGFs) are small polypeptide growth factors, all of whom share in common certain structural characteristics, and most of who m bind heparin avidly. Many FGFs contain signal peptides for secretion and are secreted into the extracellular environment, where they can bind to the heparan-like glycosaminoglycans (HLGAGs) of the extracellular matrix (ECM) . From this reservoir, FGFs may act directly on target cells, or they can b e released through digestion of the ECM or the activity of a carrier protei n, a secreted FGF binding protein. FGFs bind specific receptor tyrosine kin ases in the context of HLGAGs and this binding induces receptor dimerizatio n and activation, ultimately resulting in the activation of various signal transduction cascades. Some FGFs are potent angiogenic factors and most pla y important roles in embryonic development and wound healing. FGF signaling also appears to play a role in tumor growth and angiogenesis, and autocrin e FGF signaling may be particularly important in the progression of steroid hormone-dependent cancers to a hormone-independent state.