APOE and Alzheimer disease: Next, we also conducted IB assay and found that the levels of PSD95 and synaptophysin, two well-characterized postsynaptic and presynaptic biomarkers, were significantly decreased at 12 months old in both 3xTg and Thy1-ApoE4/C/EBPβ Tg mice versus control mice, indicating extensive synaptic loss in the brains of both AD mouse models (Supplementary Fig. 2C, D).