CYP1B1 and breast cancer: SFN reduced CYP1A1 protein level equally in nontumorigenic MCF10A breast cells, ER(+) MCF7, and ER(−) MDA-MB-231 breast cancer cells, but the increased level of CYP1A2 and the decreased level of CYP1B1 expression were found only in MCF10A cells [99].