FGF21, PPARα activation, and fasting have similar effects on the IGF-1 pathway. Mice were administered vehicle (Veh) or Wy14643 (Wy) for 10 days (left panels); vehicle (Veh) or FGF21 for 1 or 3 days (middle panels); or were fed or fasted for 24 hours (right panels). Plasma IGF-1 concentrations, hepatic IGF-1, ALS, and IGFBP-1 mRNA levels, hepatic phosphorylated STAT5 (P-STAT5) and SOCS2 protein levels and plasma insulin levels were measured. n = 4-6 mice/group except for 1 day FGF21 treatment group, where n = 3. Male mice were used in the FGF21 and fasting experiments and female mice in the Wy14643 experiment. *, P<0.05; **, P<0.01; ***, P<0.001. For the middle panels, the presence of different lowercase letters indicates statistical significance (P<0.05) between groups.