Fig. 2. ATF4 is required for glucose deprivation-induced fructolysis.

a, b U87 and LN229 cells treated without or with glucose deprivation for 18 hours in the absence or presence of indicated inhibitors were analyzed by quantitative PCR (a) and immunoblotting with indicated antibodies (b). Data were normalized with β-actin mRNA levels and presented as relative mRNA expression level (a). c, d U87, LN229 and A172 cells without or with ATF4 knockout (KO) were deprived of glucose for 18 h and then analyzed by immunoblotting with indicated antibodies (c) and quantitative PCR (d). Data were normalized with β-actin mRNA levels and presented as fold change induced by glucose deprivation (d). e U87, LN229, and A172 cells without or with ATF4 KO were deprived of glucose for 18 hours. The fructose metabolic rate was measured by monitoring the conversion of D-[5-³H] fructose to ³H₂O and normalized to cell number. c.p.m, counts per minute; WT, wild type. f U87, LN229 and A172 cells without or with ATF4 KO were deprived of glucose for 18 h and then incubated with 10 mM of fructose for another 18 h. The media were collected for analysis of fructose consumption. Data represent the mean ± SD of three (e, f) or four (a, d) independent experiments. The experiments were repeated three times independently with similar results (b, c). P values were determined by the two-tailed Student’s t-test (a, e, f). Source data are provided as a Source Data file.