CYP1B1 and breast cancer: Tangeretin was subsequently shown to induce CYP1 activity and CYP1A1/CYP1B1 expression in MCF7 and MDA-MB-468 cells, suggesting that this flavone inhibits the proliferation of breast cancer cells via CYP1A1/CYP1B1-mediated metabolism to 4′-hydroxy tangeretin [66].