MAPT and Alzheimer disease: In AD, the altered action of both proline-directed kinases, such as glycogen synthase kinase-3 (GSK3) and cyclin-dependent protein kinase-5 (CDK5), and mitogen-activated kinases (MAPKs), results in hyperphosphorylation of Tau, which dissociates from the microtubule and tends to aggregate to form characteristic neurofibrillary tangles (NFTs) [27].