ABCB1 and breast carcinoma: HIF-1α has been reported as a prerequisite for chemotherapy resistance (paclitaxel and gemcitabine) of breast cancer stem cells by inducing ROS-dependent expression of HIF-1α and HIF-2α, leading to HIF-mediated expression of IL-6, IL-8, and MDR1, thereby promoting the survival of BCSCs (80).