Glucose and glutamine fueling of CD40- and BCR-stimulated CLL cells. (A) Fluxomic analysis was performed in CLL cells stimulated with CD40 or BCR for 24 hours and subsequently cultured in medium containing either 5 mM of ¹³C₆-glucose or 1 mM of ¹³C₅-glutamine for 2 hours. For glucose-tracing experiments, culture medium also contained 1 mM of unlabeled glutamine and 5 μM carnitine, whereas in glutamine-tracing experiments, culture medium also contained 5 mM of unlabeled glucose and 5 μM carnitine. Incorporation of ¹³C in metabolic intermediates was analyzed by liquid chromatography–mass spectrometry (LC-MS). (B) Analysis of incorporation of ¹³C from fully labeled glucose (orange bars) or glutamine (green bars) in CLL cells after CD40 or BCR stimulation. Mean enrichment indicates the fraction of a given metabolite that was labeled, being 1 the total amount of that metabolite within a sample (3T3, n = 2; CD40, n = 4; BCR, n = 2; from 2 independent experiments). PPP, pentose phosphate pathway.