NGF is the first member discovered in the Neurotrophin family, which includes brain-derived neurotrophicfactor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4 (NT-4). These proteins belong to the cysteine-knotfamily of growth factors that assume stable dimeric structures. Mouse beta -NGF is a homodimer of two 120amino acid polypeptides. It shares approximately 90% homology at the amino acid level with human beta -NGFand 95.8% with rat beta -NGF. NGF signaling has been shown to play an important role in neuroprotection andrepair. β-NGF acts as a growth and differentiation factor for B lymphocytes, and enhances B-cell survival. It is apotent neurotrophic factor that signals through its receptor β -NGFR, and plays a crucial role in thedevelopment and preservation of the sensory and sympathetic nervous systems.