Fibroblast growth factor (FGF) 9 is a pleiotropic member of the FGF family. FGFs are heparin-dependent regulators of cell proliferation and differentiation (Itoh and Ornitz). FGF-9 signals by binding FGFR3 (IIIb) and the IIIc splice variants of the FGFR1, FGFR2, and FGFR3 receptors (Santos-Ocampo et al.; Mohammadi et al.; Plotnikov et al.). In mice, deletion of FGF-9 is lethal and expression of FGF-9 affects development of the skeleton, cerebellum, lungs, heart, vascular system, digestive tract, and testes (Colvin et al.; Harada et al.; Lin et al.). Altered levels of FGF-9 have also been reported in various types of human cancers (Leushacke et al.; Abdel-Rahman et al.).