1. Source: from Chinese Cobra Venom 2. Description: 3. Mol wt: Relative mol wet is about 14,500, a single line on SDS-PAGE metamorphic glue chart. Due to NGF is composed of two same mol wet subunits, and mol wt of each subunit is about 14,500, the total mol wt of NGF is 29,000 4. Identification of biologic activity: (1) quality determine : culture of chicken dorsal root ganglion. (2) quantity determine: PC12 cell culture, pheochromocytoma cells from rats adrenal gland. (3) International standard method: 1996, WHO has issued new international standard method in NGF activity identification, which is using MTT identifying to identify proliferation activity of NGF in promoting TF-1 cells. 5. Usage fields: NGF is an essential protein in the growth and development of sympathetic nerve and sensory nerve; it plays an important role in maintaining brain normal functions and adjusting internal secretion and immunity system. NGF is an ideal treatment medicine in curing relative diseases related with neuropathic damage and neuropathic retrogression, such as, brain damnification, AD, brain fever, vascular neuropathic headache, Parkinson抯 disease etc.