MAPT and Alzheimer disease: Tyr18 phosphorylation of tau occurs concurrently with an increase in phosphorylation at the AT8 epitope, an established marker of tau pathology, in transgenic mice expressing P301L tau, but not in 3xTg-AD mice, or in AD brain, in which β-amyloid (Aβ) deposition occurs alongside tau pathology [35, 277].