Fig. 3
From: Regulation of fibroblast growth factor 15/19 and 21 on metabolism: in the fed or fasted state
Physiology actions of FGF21. In response to fasting, FGF21 expression is induced in the liver by the PPARα. Secreted FGF21 acts as an endocrine hormone to induce ketogenesis and gluconeogenesis. In response to feeding, FGF21 expression is induced by the PPARγ in WAT and the ChREBP in liver, where FGF21 acts through an autocrine mechanism to stimulate PPARγ activity and glucose uptake and to repress lipolysis in liver via an endocrine mechanism