Mechanisms of resistance have been found, on the one hand in elevated expression of the multidrug resistance protein 1 (MDR1) in breast cancer cells in response to to adriamycin, or on the other hand by neutralizing the effect of oxidative-stress promoting agents due to FOXO1-elicited upregulation of anti-oxidative enzymes (e.g., paclitaxel-resistant ovarian cancer) [177,178,179]. This evidence concerns the gene ABCB1 and breast cancer.