Pharmacological strategies aiming to improve the insulin sensitivity by enhancing INSR phosphorylation seem to be promising approaches in the therapy of obesity, insulin resistance, and EMS, especially as PTP1B appears to be a critical link between the maintenance of insulin sensitivity, inflammation (both systemic and hepatic) as well as liver-related conditions. This evidence concerns the gene PTPN1 and obesity due to melanocortin 4 receptor deficiency.