_-NGF is a potent neurotrophic factor that plays a crucial role in the development and preservation of the sensory and sympathetic nervous systems. _-NGF also acts as a growth and differentiation factor for B lymphocytes and enhances B-cell survival. _-NGF belongs to the cysteine-knot family of growth factors that assume stable, disulfide-linked homodimeric structures. Recombinant human _-NGF shares approximately 90% homology with both the mouse and rat _NGF at the primary level.