Figure 7. Crosstalk between insulin and FGF21 for the regulation of metabolism.

Red arrows represent metabolic actions controlled by insulin, blue arrows represent metabolic actions regulated by FGF21, and white arrows represent the metabolic outcome induced by deletion of the IR. In LIRKO mice, insulin lost its ability to regulate glucose and lipid metabolism in the liver. In these mice, FGF21 maintained its ability to increase energy expenditure and regulate glucose homeostasis via adipose tissue, but lost its ability to regulate lipid metabolism due to a lack of interaction with insulin in liver.