Al-Dhfyan and colleagues [124] demonstrated that the activation of AhR/CYP1A1 in breast cancer MCF-7 cells by TCDD or 7,12-dimethylbenz[a]anthracene induces the overexpression of β-catenin and its downstream target cyclin D1 at mRNA and protein levels. This evidence concerns the gene CYP1A1 and breast carcinoma.