SFN reduced the CYP1A1 protein level equally in nontumorigenic MCF10A breast cells, ER-positive MCF7, and ER-negative 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 [107]. Here, ESR1 is linked to breast cancer.