MAPT and Alzheimer disease: Although studies in rodents and primates have indicated that regulation of the cell cycle plays a crucial role in controlling area-specific neuron production [27], an aberrant reactivation of the cell cycle in these neurons initiates the complex process of apoptosis [28], which likely contributes to AD development [29, 30] and is associated with the cardinal hallmarks of AD including tau hyper phosphorylation and amyloid beta (Aβ) accumulation [31] along with consequent degeneration of neurons [32].