PTPN1 and obesity due to melanocortin 4 receptor deficiency: Currently, some preclinical studies are ongoing for the PTP1B inhibitors ertiprotafib, trodusquemine, and JTT-551 for the treatment of diabetes.310,311 Another inhibitor being considered for treatment of type2 diabetes and obesity is ISIS-113715, an antisense inhibitor of the PTP1B gene.