Fig. 3.

IL-6 regulates de novo serine synthesis in TSC2-deficient cells. (A) Schematic of U-¹³C-glucose metabolism. The incorporation of ¹³C atoms from ¹³C₆-glucose into citrate, α-ketoglutarate (α-KG), succinate, fumarate, and oxaloacetate (OAA) are denoted as M + n, where n is the number of ¹³C atoms. (B–F). Fractional enrichment of the M + 3 isotopologues of serine, 3-phosphoserine, and 3-phosphoglycerate or M + 2 isotopologues of α-KG and glutamate in TSC2-deficient MEFs with IL-6 knockout compared to TSC2-deficient controls (0, 1, 3, and 24 h after labeling; Upper). Bar graphs show statistical analysis at the 24-h time point (Bottom). Data presented as mean ± SD of three biological replicates. Statistical analysis performed by one-way ANOVA. **P < 0.01, ***P < 0.001, ****P < 0.0001 or nonsignificant (n.s.) as compared to control.