Overexpression of the EGF receptor (EGFR) has been detected in many human tumors. In addition, cells in culture can be transformed by the expression of high EGFR levels. To study the regulation of the EGFR gene, we have previously isolated and characterized the promoter region of the gene and identified transcription factors that act as positive or negative regulators for this promoter region. A cDNA examined in clonal cell lines. GCF antisera reacted with a 97 kilodalton protein in cell extracts. GCF expression was also examined in EGFR negative and EGFR positive cell lines and found to be higher in EGFR negative cell lines. Cell fractionation studies were performed to show that GCF was primarily located in the nucleus but that some forms appear in the cytoplasm. GCF was determined to be a phosphoprotein with a 6-8 hour half life. Another cDNA clone has been isolated that hybridizes to one of these RNA species that contains homology to the GCF cDNA.
