FGF-22

The FGF7 subfamily, consisting of FGF3, FGF7, FGF10, and FGF22, is unique among FGFs in that its members are secreted exclusively by the mesenchyme, and specifically activate the “b” isoforms of FGFR1 (FGFR1b) and FGFR2 (FGFR2b) present in the overlying epithelium. FGF 22 is secreted from cerebellar granule cells to recruit axons projected from pontine and vestibular neurons expressing FGFR 2b. FGF 22-FGFR 2b signaling organizes synapse formation by inducing axon projection toward FGF 22 secreting cells.