Neurotrophic factor that regulates central nervous development and function. May play an important role in dopaminergic neurons in the substantia nigra. Homodimer. Interacts with FGFR2 and FGFR4. Affinity between fibroblast growth factors (FGFs) and their receptors is increased by heparan sulfate glycosaminoglycans that function as coreceptors (By similarity). Preferentially expressed in brain; substantia nigra pars compacta. Belongs to the heparin-binding growth factors family.