PTPN1 and type 2 diabetes mellitus: PTP1B plays a negative regulatory role on insulin signaling through dephosphorylation of tyrosine residues on insulin receptors substrates [14,15,16], since the overexpression of PTP1B in tissues and cells reduces the activity of protein tyrosine kinase (PTK) and prevents insulin from binding to insulin receptors, leading to insulin resistance and finally to T2DM [17].