AKR1B1 and cancer: To verify the role of the intracellular polyol pathway in glucose-fructose conversion, taking cancer incidence and malignancy into account, we blocked this pathway by deleting AKR1B1 in A549 and U87 cells, which expressed high levels of AKR1B1 (BxPC3 and HCT116 cells were used to overexpress AKR1B1 subsequently for they expressed relatively low levels of this metabolic enzyme) (Extended Data Fig. 2D and Fig. 2A).