Fig. 10. One hypothesis of regulation of BCRP and P-gp transporters by HIF-1α and Nrf2 under IH and SH. ROS: reactive oxygen species, HIF-1α: hypoxia-inducible factor 1 alpha, Nrf2: nuclear factor erythroid 2-related factor 2, BCRP: breast cancer related protein, P-gp: P-glycoprotein, IH: intermittent hypoxia, SH: sustained hypoxia.