The proto-oncogene c-erbB-1 codes for the epidermal growth factor receptor. Its name originates from the viral homolog v-erbB which was isolated from an avian erythroblastosis virus (AEV) where it was contained as a fragment of the chicken c-ErbB-1 gene lacking the amino-terminal ligand-binding domain. Overexpression of erbB-1 genes occurs in a wide range of tumors, commonly squamous carcinomas of various sites and less commonly adenocarcinomas. The human c-erbB-1 gene is located in the chromosomal region 7p14 and 7p12.