FGF-5

FGF-5 is best known as the master switch of the hair cycle. Expressed in the outer root sheath of the follicle at the end of anagen, it drives the transition into catagen, and loss-of-function FGF5 mutations produce the long-hair phenotype in mice, dogs, cats and humans. Beyond hair biology, FGF-5 is expressed in brain and vascular tissue, and variants at the FGF5 locus on chromosome 12 have been linked in genome-wide studies to hypertension and cardiovascular risk. FGF-5 signals mainly through FGFR1c. Recombinant FGF-5 is used in hair-follicle organ culture, catagen-induction assays and screening of hair-growth modulators.