The advantage of employing human neuronal cells is not only in that they are from the species affected by the disease and therefore reflect more faithfully cellular AD pathology but also because they possess a mechanism capable of the AβPP-independent production of C99 (presumably the RNA-dependent AβPP mRNA amplification pathway but in unlikely case other mechanisms, discussed in Section 22 below, are involved, they are also in place). The gene discussed is APP; the disease is Alzheimer disease.