MAPT and Alzheimer disease: Extensive analysis of the human AD brainhas shown the presence of many hyperphosphorylated tau sites, whichpromote tau aggregation and the formation of neurofibrillary tangles.3 Several phosphorylated residues are significantlyenriched in the cerebrospinal fluid (CSF) of AD patients.4 The exact mechanism or the critical phosphorylationsites are not yet known.