Fibroblast growth factor 6 (FGF-6) is a heparin-binding member of the FGF family, regulators of cell proliferation, differentiation, and function. FGF-6 binds and signals through the FGF receptors 1c, 2c, and 4 (Ornitz et al.). FGF-6 is a potent mitogen for fibroblasts, vascular endothelial cells, and prostate carcinoma cells (Asada et al.; Pizette et al.; Ropiquet et al.). FGF-6 is primarily expressed in epithelial and mesenchymal cell lineages. During development, FGF-6 is expressed in skeletal muscle, consistent with its role in muscle differentiation and regeneration (Floss et al.). FGF-6 has also been shown to promote chondrogenesis in embryonic somites in conjunction with transforming growth factor beta 2 (TGF-β2; Grass et al.).