MARK2 and Alzheimer disease: Glycogen synthase kinase-3 (GSK3) is a serine/threonine kinase substrate of Akt, inhibited by Akt, that plays a key role in the pathogenesis of AD contributing to amyloid-β production, amyloid-β-mediated neuronal death, and hyperphosphorylation of microtubule-associated protein tau [177].