G6PD and neoplasm: Metastatic tumours reveal enhanced PPP flux for resistance of microenvironment change.30 G6PD, the rate-limited enzyme in the pentose phosphate pathway, is a critical enzyme that regulates cell proliferation and tumour formation.31,32 It has been reported that G6PD deficiency reduces the susceptibility for developing endodermal-origin cancer,33 but the role and mechanism of G6PD plays in cancer metastasis remains unclear.