In the so-called non-amyloidogenic pathway, CTF83 is digested by γ-secretase, a complex with presenilin 1 at its catalytic core [54] (for γ-secretase reviews see [55-59]), releasing the APP intracellular domain (AICD) which may contribute to the toxicity of AD [60] and the extracellular p3 element with as yet no known function (reviewed in [61,62]). Here, APP is linked to Alzheimer disease.