Description: Fibroblast Growth Factor basic (FGF-b, also known as FGF-2) is a member of the FGF family, a highly conserved family of 16-34 kDa heparin-binding proteins. FGF-b exists in several isoforms, and although they are equally active, only the 18 kDa form is secreted while the 23 kDa form localizes to the nucleus. They share four common tyrosine kinase receptors, FGFR 1-4, and require the binding of a second surface protein, the ubiquitously expressed heparan sulfate proteoglycan, in order to fully activate these receptors. FGF family members affect the proliferation, differentiation, mobility, and survival of several cell types, including fibroblasts, osteoblasts, smooth muscle cells, and neuroblasts. FGF-b expression has been detected in several cell types, including fibroblasts, macrophages, endothelial cells, epithelial cells, and neurons. It lacks the signal sequence peptide necessary for the ER/Golgi pathway, indicating that secretion occurs via an alternate pathway. They are particularly important in embryonic development as triggers of neurogenesis, angiogenesis, and neovascularization. FGF-b has most recently been studied for its ability to maintain the proliferation of embryonic stem cell cultures in an undifferentiated state. Some members of the family, including FGF-b, remain active during adulthood and play a role in bone formation and tissue repair. FGF family members are also implicated in many types of cancer and may contribute to tumor vascularization.