Nerve growth factor and the skin

Nerve growth factor (NGF) is a neurotrophic polypeptide required for the survival and differentiation of sensory and sympathetic neurons (1, 2). NGF belongs to a small family of structurally and functionally related proteins termed neurotrophins (NTs), which include brain-derived neurotrophic factor (BDNF) (3), NT-3 (4) and NT-4/5 (5). All neurotrophic molecules exert their effect by binding two classes of transmembrane receptors. A low affinity receptor of similar to 75 kD (p75) (6), and a high affinity, tyrosine kinase receptor, of similar to 140 kD that belongs to the trk family of receptors (7, 8).