HCC4006 cells were treated with vehicle (DMSO) or 100 nM erlotinib for 22 hours in replicates of three. Cell extracts were processed for metabolic profiling using UPLC-MS/MS. A. Levels of glycolysis metabolites B. Levels of TCA cycle intermediates. ANOVA; *P ≤ 0.05, **P ≤ 0.01, ***P ≤ 0.001 for comparisons of all samples to vehicle-treated control shNT cells, and pound signs indicate statistical significance (#P ≤ 0.05, ##P ≤ 0.01, ###P ≤ 0.001) for comparisons of CPS1 knockdown cells to control shNT cells under the same treatment conditions.