IARS1 and Alzheimer disease: An overall reduction of IRS activity in the young 3xTg-AD mice was suggested by the decreased phosphorylation of IRS at Tyr608 (activation) and increased phosphorylation of IRS at Ser307 (inactivation); however, this could not be explained in lieu of the Akt data i.e., IRS activation was decreased by ~40% in the young 3xTg-AD mice whereas the effect on Akt activation was rather minimal.