Higher levels of CPR were observed in MCF-7/DOXR cells and its central key role in the metabolism of drugs, cholesterol, fatty acids, heme homeostasis (via heme oxygenase) and steroid hormone biosynthesis, is indicative of the potential implications of this oxidoreductase in tumorigenesis and cancer DR [12,21,37,65]. The gene discussed is POR; the disease is cancer.