APP and Alzheimer disease: The role of Aβ peptides in those processes was further investigated by Oh et al., who demonstrated that increased Aβ levels paralleled decreased chymotrypsin-like activity of the 26S proteasome in cortex and hippocampus of Tg2576 mice, a well characterized AD animal model that ubiquitously expressed Swedish mutant amyloid precursor protein (APPswe) [55].