APP and Alzheimer disease: Given theprobable role of mitotic re-entry in AD, it is notable that APP is upregulatedsecondary to mitogenic stimulation [58] and thatAPP metabolism is regulated by cell cycle-dependent changes [59].Interestingly, Aβ itself is mitogenic in vitro [60,61] andtherefore may play a direct role in the induction and/or propagation of cellcycle-mediated events in AD.