APP and Alzheimer disease: Recently, the co‐localization of C‐terminal APP fragments with Aβ was observed in cellular regions, including autolysosomes, perinuclear compartments, and multi‐vesicular bodies, in the brains of AD transgenic mice.[5, 20, 21, 22] Moreover, the studies with the C‐terminal truncated APP, APP1–664, and mutant APP(Asp664Ala) suggested that Aβ could activate caspases inducing the C‐terminal cleavage of APP generating APP‐C31.[17, 18, 19, 22] Despite these indications, the mechanism of how APP‐C31 is involved in the pathology driven by Aβ is not known to date.