Expression of GIPR and GLP-1R mRNA in HUVECs using reverse transcription-polymerase chain reaction and western blot analysis. (A) mRNA expression of GIP and GLP-1 receptors present in HUVEC and (B) protein expression level of GIP and GLP-1 receptors present in HUVEC is lower than in islet cells. GAPDH and β-actin were used as controls. Data are presented as mean ± standard deviation. ***P<0.001 vs. control cells, GIP, glucose-dependent insulinotropic polypeptide; GLP-1, glucagon-like peptide 1; HUVEC, human umbilical vein endothelial cells; GIPR, GIP receptor; GLP-1R, GLP-1 receptor.