The amount of 13C-labeled glycolysis intermediates, fructose 1,6-bisphosphate, dihydroxyacetone phosphate, glyceraldehyde 3-phosphate, 3-phosphoglycerate, phosphoenolpyruvate and lactate, was elevated in PD-1-deficient lymphoma cells (Fig. 3a), indicating enhanced glucose usage within the canonical upper glycolytic pathway. Here, PDCD1 is linked to lymphoma.