The specific receptar for epidermal growth factor(EGFR) was first purified from the A431 cell line which was derived from an epiderrnal carcinoma of the vulva. It is a 170,000 dalton transmembrane glycoprotein and has three components, an extracellu~lar domain capable of binding the ligan~4 a transmembrane portion, and an intracellular domain facing the cytoplasm. The receptor is capable of binding epidermal growth factorgGF), transforming growth factor(TGF) a, amphiregulin, and heparin-binding EGF. The function of EGFR is to bind the mitogen EGF or TGF a and to transduce the signal across the cell membrane to the cytoplasm. The intracellular component exhibits tyrosine kinase activity and has binding sites for ATP. This results in the autophosphorylation of the EGFR and phosphorylation of several target proteins. It has been suggested that the EGFR is overexpressed in the A431 cell line and that there is a close correlation hetween EGFR, EGFR mRNA overexpression and EGFR gene amplification. However this has not been always demonstrated in cervical cancers and cell lines. (continue...)