Hepatocyte Growth Factor (HGF), also known as Hepatopoietin A and Scatter Factor, was originally identified based on its mitogenic activity for hepatocytes. Plasma from patients with hepatic failure was found to contain a factor that stimulates the growth of rat hepatocytes in primary culture. This plasma-derived HGF was purified and found to have multiple forms with molecular weights between 76 kD and 92 kD. Mature HGF consists of 2 disulfide-linked chains, heavy and light, with molecular weights of 54-65 kD and 31.5-34.5 kD, respectively. The heavy and light chains are encoded by the same mRNA, which by translation yields a biologically inactive single chain pro-peptide. The pro-peptide is cleaved by an extracellular serum serine protease to form the bioactive disulfide-linked alpha and beta chain heterodimeric HGF. HGF has also been described as Scatter Factor, based on its capacity to stimulate the dissociation and scattering of epithelial cells. The sequence of HGF has about 35% identity to that of plasminogen and the putative cleavage site of HGF is identical to that of plasminogen. The HGF receptor gene, the MET oncogene, is located on 7q, along with the HGF gene. An increase in the copy number of chromosome 7 is one of the most common chromosome abnormalities observed in human malignant gliomas.