ABCB1 and cancer: Among them, FOS-promoting cell autophagy [38] was upregulated, whereas PI3K (PIK3CA/PIK3CB), which is a key signaling factor in cancer and was found to regulate ABCB1-mediated MDR in our recent study [2], was downregulated accompanying the remarkable downregulation of ABCB1 (Fig. 4A, B and C).