PSEN1 and Alzheimer disease: Consistent with the Western blot analysis results, BACE1 and SNX4 levels in the brain tissue of 6-month-old APP/PS1 mice were increased compared with those of wild-type mice, whereas SNX4 levels were decreased and BACE1 levels were unchanged in the brain tissue of 24-month-old APP/PS1 mice and AD brain compared with controls (Figs. 2 and 3). BACE1 antibody specificity was verified additionally (Additional file 2: Figure S2).