Both glucose-deprived ECs and cancer cell types exhibit an abbreviated GNG, but cancer cells utilize reverse glycolysis for nucleotide synthesis by diverting glycolytic intermediates into serine biosynthesis pathway and PPP (relying on the rate-controlling GNG enzyme FBP)11,12, while ECs shunt glycolytic intermediates into the serine biosynthesis pathway, but carbons from non-carbohydrate substrates were not detected in PPP-generated riboses in ECs. This evidence concerns the gene FBP1 and cancer.