IARS1 and Insulin resistance: Pro-inflammatory cytokines released by M1 macrophages, such as TNF-α and IL-6, are able to induce cellular insulin resistance at the level of insulin receptor/insulin receptor substrate (IRS) tyrosine dephosphorylation [11] as well as IRS serine phosphorylation via several IRS kinases including c-Jun N-terminal kinase [JNK], inhibitor of κB kinase, and protein kinase C [12].