GLP-1R and GPR120 (also known as free fatty acid receptor 4), for example, are both promising therapeutic targets for the treatment of type 2 diabetes and obesity.74,92 Mechanistically, the endogenous ligand of GLP-1R, GLP-1, can reduce the secretion of glucagon in pancreatic α cells and promote insulin secretion in pancreatic β cells. This evidence concerns the gene GCG and obesity due to melanocortin 4 receptor deficiency.