Ben‐Yoseph et al [52] studied the label loss from [1,6,6’‐2H3]glucose in rat glioma cells and found that there are two potential loss routes for the C1 label: a lesser mechanism via the pentose‐phosphate pathway and a greater mechanism caused by the action of phosphomannose isomerase on fructose‐6‐phosphate during glycolysis, together producing up to 52% loss for the C1 labels. Here, MPI is linked to central nervous system cancer.