Fibroblast growth factor 16 (FGF-16) is a heparin-binding member of the FGF family. FGFs possess broad mitogenic and cell survival activities and are expressed during embryonic development. FGFs act primarily on cells of mesodermal and neuroectodermal origin to regulate diverse physiological functions including angiogenesis, cell growth, pattern formation, embryonic development, metabolic regulation, cell migration, and tissue repair (Goldfarb; Green et al.). In vitro, FGF-16 has been shown to promote the proliferation of brown adipocytes and in rat embryos it is predominantly expressed in these cells. FGF-16 has also been shown to play a critical role in embryonic heart development and is thought to play a cardioprotective role after birth (Hotta et al.; Lu et al.; Wang et al.).