G6PD and neoplasm: Considering that ectopic G6PD expression increases the levels of nicotinamide adenosine dinucleotide phosphate (NAPDH) and glutathione, G6PD may promote the survival of tumor cells through maintenance of both extracellular pH and redox potential [19,20], though little is known about how G6PD regulates cell proliferation and apoptosis in tumors.