Fibroblast Growth Factor Receptors (FGFRs) 1-5 have common structural features which consist of an extracellular ligand-binding section composed of three domains (Ig domains I, II, and III), a transmembrane domain, and an intracellular tyrosine kinase catalytic domain. At least 22 ligands (FGFs) are known that signal through FGFRs 1-5. In FGFR-1 alternative splicing of the exon encoding the third IgG-like domain produces the b- or c-splice form both of which have distinct ligand-binding preferences. The FGFR1c splice form has been shown to regulate food intake.