APP and Alzheimer disease: Consequently, if the AUG encoding Met671 of human AβPP were utilized in the initiation of translation, both C100 and Met-Aβ should be present in the AD-affected neurons or in the human neuronal cells-based AD model [7,205] (it should be noted that neither would occur in postmortem samples because in dying cells protein synthesis stops long before proteolysis does; without the influx of C100, the conversion of preexisting C100 and Met-Aβ into C99 and Aβ would be complete).