Fibroblast growth factor 9 (FGF-9) encoded by the FGF-9 gene is a member of the fibroblast growth factor (FGF) family. It plays an important role in the regulation of embryonic development, cell proliferation, cell differentiation and cell migration. In addition, this protein was isolated as a secreted factor that exhibits a growth-stimulating effect on cultured glial cells and it is a heparin-binding protein. Furthermore, FGF-9 is a monomer and interacts with FGFR1, FGFR2, FGFR3 and FGFR4. Recombinant mouse FGF-9 is synthesized as a 208 a.a. precursor that contains a 3 a.a. signal sequence. Specifically, The mouse FGF-9 shares 99 % a.a. sequence identity with rat FGF-9.