Nerve growth factor (NGF) is a naturally occurring molecule in the body which stimulates the growth and differentiation of the sympathetic and certain sensory nerves. NGF is a protein that consists of 3 types of polypeptide chains -- alpha, beta and gamma -- that interact to form the protein. The NGF beta chain (NGFB) is solely responsible for the nerve growth stimulating activity of NGF. The NGFB gene is in chromosome band 1p22. An ointment containing NGF has been reported to help heal bedsores (decubiti).This complex contains 2 identical 118-amino acid beta-chains, which are solely responsible for nerve growth stimulating activity of NGF. Human DNA fragments coding for NGF were identified by Zabel et al. (1984) using a mouse submaxillary cDNA probe.