Moreover, an in vitro study has shown 17 β-estradiol to upregulate the expression of CYP2B6 exclusively in T-47D but not in MCF-7 breast cancer cells by increasing the recruitment of ER-α and nuclear receptor coactivator 3 (NCoA3) to the 5’ flanking region of the enzyme [64]. This evidence concerns the gene CYP2B6 and breast cancer.