INS and obesity due to melanocortin 4 receptor deficiency: However, in one study that utilized ventricular cardiomyocytes isolated from an ob/ob mouse model of obesity and type 2 diabetes, it was demonstrated that insulin increased IP3 concentration while the expression of type 1 and type 2 IP3R was unaltered compared to wild-type controls (Fauconnier et al., 2005).