PTPN1 and Insulin resistance: SIRT1 modifies the activity of PTP-1B at the chromatin level by deacetylating the Lys9 of histone H3, and reduces its binding in the promoter region for PTP-1B, as shown in an in vitro study of C2C12 murine myotubes by Sun et al. [75] after recombinant HSV encoding SIRT1 infection and induction of insulin resistance by palmitate.