FGF21 is required for c-Jun regulation of glucose metabolism. (A–F) c-jun△li mice or control mice were injected with Ad-FGF21 (+Ad-FGF21) or Ad-GFP (- Ad-FGF21), followed by examination of FGF21 and c-Jun expression at day 14 in A, measurement of serum FGF21 levels at day 14 in B, fed blood glucose and serum insulin levels at day 2 or fasting blood glucose and serum insulin levels at day 3 in C and D, performance of GTTs and PTTs at day 3 or 7 in E and F. Data were obtained with mice indicated (n = 6–10 mice per group, 10–12 weeks old) and presented as means ± SEMs. Statistical significance was calculated using the one-way ANOVA followed by the Student-Newman-Keuls (SNK) test in A-F (*: p < 0.05 for the effects of any group of mice versus control mice injected with Ad-GFP; #: p < 0.05 for the effects of Ad-FGF21 versus Ad-GFP in c-jun△li mice).