In Alzheimer’s disease, Aβ is generated from APP through sequential cleavages, first by β-secretase and then by γ-secretase complex, the latter consisting of at least four components: presenilin (PS, PS1 or PS2), Nicastrin, anterior pharynx-defective-1 (APH-1) and presenilin enhancer-2 (PEN-2) [179,180]. Here, APP is linked to Alzheimer disease.