PTPN1 and obesity due to melanocortin 4 receptor deficiency: Due to the structural similarity of berberine and papaverine, it also inhibits human protein tyrosine phosphatase 1B (PTP-1B) [14] which plays a major rule in the development of diseases associated with insulin resistance such as obesity and diabetes as it is involved in the dephosphorylation of tyrosine residues of the insulin receptors [15].