Fibroblast Growth Factor 18 （FGF-18） plays an important role in skeletal development and bone homeostasis. Mature human FGF-18 shares 99% amino acid sequence identity with mouse and rat FGF-18. It is expressed in embryonic somites and the neural fold, adult lung, cerebellar and hippocampal neurons, hair follicle root sheath cells, and osteogenic mesenchymal cells. 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, postnatal growth and regeneration of a variety of tissues, by promoting cellular proliferation and differentiation. FGF-18 is required for normal skeletal development. Recombinant Human FGF-18 derived from E.coli is a 20 kDa protein consisting of 173 amino acid residues, resulting from C-terminal truncation of the full length protein.