HIF1A and neoplasm: Driven by HIF-1α, drug efflux pumps such as P-glycoprotein (P-gp) are over-expressed, which can not only protect tumor cells by pumping cytotoxic chemotherapeutics to the extracellular spaces but also protect the molecular targets by transporting drugs into the lysosomal lumen from the cytoplasm (Harhaji-Trajkovic et al., 2009; Peng et al., 2014; Lee et al., 2015).