Overall, the data aforementioned suggest that Spino−/− mice are lean and have improved glucose tolerance, that obesity modulates spinophilin protein-protein interactions within the pancreas, and that spinophilin is expressed in, and interacts with, PP1, ribosomal, cytoskeletal, and enzyme proteins isolated islets. Here, PPP1R9B is linked to obesity due to melanocortin 4 receptor deficiency.