Glucose-6-phosphate dehydrogenase (G6PD) is the rate-limiting enzyme of the PPP, and hypoxia triggers its O-GlcNAcylation at Ser-84 in human lung cancers, leading to G6PD activation and metabolic flux into the PPP to produce intermediates of nucleotide and lipid biosynthesis in cancer cells (26). This evidence concerns the gene G6PD and lung cancer.