CYP2E1 and breast cancer: To gain further insight in the transcriptional regulation of the CYP2E1 gene expression and investigate the potential role of p53 in the regulation of the cellular levels of this enzyme the luciferase activity of the CYP2E1-Luc reporter containing the putative p53 binding sites [44] identified in the regulatory region of the promoter of this gene was studied in MCF-7 breast cancer cells.