FIGURE 1.
Diagram depicting [1,2-13C2]-glucose metabolism through glycolysis and the pentose phosphate pathway (PPP) with the resulted labeling pattern of lactate C3. As a consequence of the higher activity of glycolysis relative to PPP in normal cells, the contribution of the doublet (D23) to the total NMR signal of lactate C3 is significantly more prominent than the singlet (S3). HK: hexokinase, G-6PDH: glucose 6-phosphate dehydrogenase, 6PGDH: 6-phosphogluconate dehydrogenase, PGI: phosphoglucose isomerase, LDH: lactate dehydrogenase, Glc: glucose, Glc-6-P: glucose 6-phosphate, F6P: fructose 6-phosphate, G3P: glyceraldehyde 3-phosphate, 6PG: 6-phosphogluconate, R5P: ribose 5-phosphate, PYR: pyruvate, LAC: lactate. Open circles denote carbon 12, filled circles denote carbon 13.