GMPs use glutamine in vitro to generate TCA cycle intermediates. LC/MS analysis of ¹³C incorporation into TCA cycle intermediates following a 24-h culture of WT GMPs with uniformly ¹³C-labeled glucose, BCAAs (leucine [leu]/isoleucine [ile]/valine [val]), glutamine (gln), palmitate, pyruvate, lactate, alanine (ala), acetate, asparagine (asn), lysine (lys)/phenylalanine (phe)/tryptophan (trp)/tyrosine (tyr)/cysteine (cys)/glycine (gly)/serine (ser), or glutamate (glu)/arginine (arg)/histidine (his)/proline (pro)/methionine (met)/threonine (thr)/phenylalanine (phe)/tyrosine (tyr)/aspartate (asp). Labeling data were corrected for natural-abundance ¹³C. Mean values ± SEM are shown for three to five replicates from two independent experiments for each ¹³C-labeled carbon source. Cells were pooled from five mice per each carbon source for each experiment.