Recombinant HEK293 cells expressing firefly luciferase gene under the control of cAMP response element (CRE) with constitutive expression of human GLP-1R (Glucagon-like peptide 1 receptor; accession number BC113493)._x000D_GLP-1R, a member of the class B family of G protein-coupled receptors (GPCRs) primarily found in pancreatic β cells, is activated by a peptide hormone, glucagon-like peptide 1 (GLP-1) that is secreted from intestinal L-cells after nutrient ingestion. GLP-1R plays an important role in controlling blood sugar level by enhancing glucose-stimulated insulin secretion, so various research efforts have focused on the regulation of the GLP-1R mediated signaling pathway as a therapeutic approach to diabetes.