Figure 5: 13C NMR spectra of perchloric acid extracts for the three colorectal cancer cell lines under normoxia and high glucose media: (a) WiDr; (b) LS1034; (c) C2BBe1. Expanded is the multiplet due to glutamate carbon 4 (C4-Glu; 34.2 ppm), composed by two major multiplets, duplet 45 (D 45), due to glutamate isotopomers labeled in carbons 4 and 5 but not carbon 3, and quartet (Q) representing all glutamate isotopomers with those three carbons enriched simultaneously. Other resonances easily seen are the methyl carbons of lactate (C3-Lac; 20.8 ppm) and alanine (C3-Ala; 17.0 ppm) and the carbon 3 of glutamate (C3-Glu; 27.8 ppm).