Assay setup: cells are plated on collagen I-coated 384-well plates and exposed to compounds (mitogens) of interest; harmine is used as a positive control. Cells are labeled for specific markers to identify proliferating beta-cells. Plate imaging is automated with a template matrix using the Multiple Mosaics application (Leica HCS A suite). Counting cells in the obtained images can be automated using the Surfaces and Spots functions in Imaris 7.6 software to identify beta-cells by both cytoplasmic insulin and nuclear Pdx1, and proliferating cells by nuclear Ki-67.