Of these, the large ectoplasmic soluble APPα fragment (sAPPα; generated by α-secretase) exerts neurotrophic effects, the smaller amyloid-β (Aβ) peptides (products of β- and γ-secretases) have been shown to play a pivotal role in AD pathogenesis, while APP Intracellular domain (AICD), a product of γ-secretase activity, regulates intracellular signaling and likely also contributes to AD pathogenesis [5], [6]. Here, APP is linked to Alzheimer disease.