CPF induced cell proliferation in MCF-7 and MDA-MB-231cells after 1 and 14 days of treatment by AhR activation through thePGE2/Wnt/β-catenin pathway and HSP90 and HSP70 overexpression.Our results reveal new information on CPF toxic mechanisms inducedin human breast cancer cell lines, which could assist in elucidatingits involvement in breast cancer. The gene discussed is NR5A2; the disease is breast carcinoma.