CAT and Alzheimer disease: Although our use of artificial AT repeats is sufficient to mimic the effect of aberrant APP.C99 in facilitating Aβ-42 aggregation, future biochemical studies will determine the nature of the CAT-tails formed on APP.C99 in AD condition, as amino acids other than A and T can be incorporated into CAT-tails in flies and mammalian cells [35, 58].