APP and Alzheimer disease: At the molecular level, the main pathological hallmarks of AD include the abnormal aggregation of amyloid‐beta (Aβ) peptides produced from sequential proteolytic cleavages of amyloid precursor protein (APP) by β‐secretase and γ‐secretase, as well as the formation of neurofibrillary tangles (NFT) formed by hyperphosphorylated tau protein in brain.17, 18