Association of GLP-1 receptor ligand complex with Rab5 endosomes. BRIN-BD11 pancreatic beta cells were transfected with GFP-tagged GLP-1R and, following stimulation with 100 nM Exendin-4 for 0 min, 15 min, and 40 min, the cells were fixed, immunostained with Rab5 rabbit monoclonal antibody, counterstained with goat anti rabbit secondary antibody, and visualized by confocal microscopy. The data are representative of three independent experiments (n = no. of cells assessed for each time point n = 11).