LEF1 and breast cancer: In addition to the beneficial effect of quercetin used alone, it can enhance the efficacy of other molecules in BC as was demonstrated for docetaxel, whose cytotoxic activity was synergistically potentiated by quercetin (40 μM) in MCF7-DR (drug resistance) where it led to the decrease in lymphoid enhancer-binding factor 1 (Lef1), a protein strongly associated with cell drug resistance.