PSEN1 and Alzheimer disease: Endogenous RanBP9 protein levels were significantly increased by 3.5-fold in the hippocampus of 8-month-old APP/PS1 mice by immunoblotting (Figures 4a and b), consistent with our previous observations in 12-month-old J20 mice harboring the ‘Swedish' mutation and in AD brains.18, 19 Further, immunohistochemical analysis of APP/PS1 mouse hippocampus demonstrated greatly enhanced RanBP9 levels in the dentate gyrus (DG) and CA3 regions compared with WT littermates (Figure 4c).