PPIB and Alzheimer disease: Due to neuropathological similarities between AD and NPC diseases, Kodam and colleagues previously examined protein levels and distribution of APP and its processing enzymes, β- and γ-secretase, in the same mouse model of NPC disease, as used in our study, and detected a statistically significant increase in BACE1 protein levels in NPC1 vs. wt mice in cerebellum at 7- and 10-weeks of age and in hippocampus at 10-weeks of age [27].