The 5' flanking region of the pS2 gene contains a complex enhancer region responsive to oestrogens, epidermal growth factor, a tumour promoter (TPA), the c-Ha-ras oncoprotein and the c-jun protein.

Expression of the pS2 gene which is transcriptionally controlled by oestrogens in the breast cancer cell line MCF-7 is oestrogen independent in stomach mucosa. We show here that the level of MCF-7 cell pS2 mRNA can also be increased by the tumour promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). We further demonstrate, using transient transfection assays, that the -428 to -332 5' flanking sequence of the pS2 gene contains DNA enhancer elements responsive to oestrogens, TPA, EGF, the c-Ha-ras oncoprotein and the c-jun protein.