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. 2021 Sep 20;118(39):e2101268118. doi: 10.1073/pnas.2101268118

Fig. 4.

Fig. 4.

PSAT1 rescues proliferation of TSC2-deficient, IL-6 knockout cells. (A) Diagram depicting interrelationships between glycolysis, the PPP, de novo serine biosynthesis, and the TCA. (B–D) PHGDH, PSAT1, and PSPH mRNA levels are decreased in TSC2-deficient, IL-6 knockout cells compared to TSC2-deficient control MEFs. (E) PSAT1 mRNA levels in IL-6 knockout, TSC2-deficient cells are rescued upon rIL-6 treatment (200 pg/mL; 24 h). (F–I) Western blot and densitometry showing expression of de novo serine biosynthesis enzymes and decreased PSAT1 expression in IL-6 knockout cells compared to control cells. Blots are from the same gel. Some lanes were cropped out for visualization purposes. (J) Western blot confirming PSAT1 overexpression in TSC2-deficient, IL-6 knockout cells and TSC2-deficient controls. Blots are from the same gel. (K) PSAT1 overexpression rescues proliferation of IL-6 knockout, TSC2-deficient cells (72 h; fold change relative to day 0, when the cells were washed and put into serum-free media). The data are presented as the mean ± SD of three independent experiments. One-way ANOVA was used for statistical analysis. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001 as compared to control.