INS and type 2 diabetes mellitus: These findings suggest that Rho GTPase signaling affects not only the dendritic spine structure but also a number of cellular processes, including insulin release from pancreatic islet β-cells, and that aberrations in Rho GTPase signaling, including its activation by GEFs, could therefore contribute to the comorbidity of schizophrenia and T2DM (Figure 1).