MAPT and Alzheimer disease: Glycogen synthase kinase 3 is a type of serine/threonine kinase enzyme by constitutive and ubiquitous proline involved in various cellular processes, which has two isoforms, α, and β, and are closely related to hyperphosphorylation of tau protein, impaired memory, and increased accumulation of beta-amyloid plaques.(82) Glycogen synthase kinase 3 beta (GSK3β) has also been shown to reduce the synthesis of acetylcholine, which agrees with the cholinergic deficit presented in AD.(83) Furthermore, GSK3β is a critical mediator in cell apoptosis, thus contributing to neuronal loss seen in AD.(84)