Detection of ErbB Receptor Family Tyrosyl Phosphorylation in Ovarian Carcinoma Cells

The epidermal growth factor receptor (EGFR) (ErbB) family of receptor tyrosine kinases is frequently overexpressed in ovarian cancer (1 ) . This receptor group is comprised of four members, EGFR (ErbB-1), HER2 (ErbB-2), HER3 (ErbB-3), and HER4 (ErbB-4). These receptors share a common molecular architecture, possessing a large glycosylated extracellular ligand-binding domain, a single hydrophobic transmembrane domain, and a cytoplasmic tyrosine kinase domain (2 ). Amplification and over- expression of ErbB-2 have been reported in ovarian carcinoma, where high levels of ErbB-2 directly correlate with poor clinical prognosis (3 ,4 ). Amplification of EGFR has also been reported, and may have prognostic significance (5 ,6 ). Less is known about the clinical significance of ErbB-3 (7 ) and ErbB-4 (8 ), which have been more recently identified.