Fig. 3

Serine starvation induces AMPKα activation to inhibit mTORC1 signaling pathway. A The levels of AMP, ADP, ATP, and AMP/ADP ratio in KYSE150 cells after serine starvation for 24 h were detected by using a targeted metabolomics approach (n = 6 per group). B, C The levels of AMPKα/mTORC1 signaling pathway in ESCC cells grown in Com or -Ser medium with the supplementation of 1 mM FA for 24 h were detected by western blotting. β − actin was the loading control. D The levels of AMPKα/mTORC1 signaling pathway in siPRKAA1 ESCC cells grown in Com or -Ser medium for 24 h were detected by western blotting. β − actin was the loading control. E The levels of AMPKα/mTORC1 signaling pathway in ESCC cells grown in Com or -Ser medium with or not 10 μM compound C for 2 h were detected by western blotting. β − actin was the loading control. F The number of siPRKAA1 ESCC cells grown in Com or -Ser medium for 48 h. Data are presented as mean ± SD. Unpaired two-sided Student’s t test. ns: no significance, *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001