Fig. 2.

Utilization of glutamine as a carbon source for GPL glycerol backbone biosynthesis in starved lung cancer cells. (A) Metabolic pathway for the biosynthesis of glycerol phosphate from glutamine (glyceroneogenesis) via PEPCK-M. (B) Incorporation of carbons from ¹³C₅-glutamine into the glycerol backbone of different GPL classes in A549 cells grown in low glucose (0.2 mM) medium. (C) Modulation by exogenous glucose. (B and C) Data are mean ± SEM from three independent experiments. (D) A549 cells were incubated with ¹³C₅-glutamine for 12 h in medium containing different concentrations of glucose after preincubation without label for 60 h. Label enrichment is shown as mean ± SEM from four experiments. *P < 0.05, **P < 0.01, ***P < 0.001 on one-way ANOVA with Dunnett post hoc analysis versus 24 h (B) or 0.2 mM Glc (C and D).