Acidic and basic fibroblast growth factors (FGFs) are members of a family of multifunctional polypeptide growth factors that stimulate proliferation of cells of mesenchymal, epithelial and neuroectodermal origin. Like other growth factors, FGFs act by binding and activating specific cell surface receptors. These receptors usually contain an extracellular ligand-binding region containing three immunoglobulin-like domains, a transmembrane domain and a cytoplasmic tyrosine kinase domain. Fibroblast growth factor- 22 (FGF-22) is a secreted protein whose gene is localized to human chromosome 19p13.3. FGF-22 is expressed preferentially in the inner root sheath of the hair follicle, suggesting that it is important in hair development.