APP and Alzheimer disease: The 3×Tg model, which harbors two familial AD mutations, APP(Swe) and PS1(M146V), and the tau(P301L) mutation found in frontotemporal dementia, has been integral in studies of the relationship between amyloid β-protein (Aβ) and tau [25], [26], and has been used to assess the role of intraneuronal Aβ [27], [28] and several potential therapies for AD [29], [30].