FGF-18 is a heparin binding growth factor that belongs to the FGF family. Proteins of this family play a central role during prenatal development and postnatal growth and regeneration of a variety of tissues, by promoting cellular proliferation and differentiation. FGF-18 is an essential regulator of long bone and calvarial development. FGF-18 signals through FGFR 1c, 2c, 3c, and 4. Recombinant E.coli derived human FGF-18 is a 20.1 kDa protein consisting of 173 amino acid residues, resulting from c-terminal truncation of the full length protein.