Epidermal growth factor receptor gene expression in response to the tumor promoting phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) was analyzed in the A549 human lung adenocarcinoma cell line using DNA transfection. After 8 h of treatment a definite repression (45%) of EGF receptor gene transcription could be seen. Repression was maintained for up to 24 h. Little or no induction of transcription could be seen prior to the onset of repression for potential enhancer regions both upstream and downstream of the translation start site. The cis-element(s) responsible for repression were localized between residues -384 and -151 of the EGF receptor gene promoter region using a deletion plasmid series.