PTPN1 and Insulin resistance: SIRT1 also enhances insulin secretion from the pancreatic beta cells by regulating the expression of uncoupling protein 2 (Ucp2) (42), and decreases insulin resistance via reducing the expression of the proteins in the insulin receptor signaling pathway, such as protein tyrosine phosphatase 1B (PTP1B), and by inhibiting insulin-induced IRS-2 (insulin receptor substrate-2) tyrosine phosphorylation by deacetylation (46, 47).