Moreover, it has been known that the nonionic PEO/PPO block copolymer, such as Pluronic F68 used in this study, may reduce P-glycoprotein activity of the drug-resistant cells by decreasing their ATP production [48], and that may diminish the level of medicinal resistance in the HER2-overexpressing breast cancer cells accordingly. Here, ABCB1 is linked to breast carcinoma.