BACE1 and Alzheimer disease: Out of these, 12 proteins (31%) were related to hallmark AD pathology (Aβ and tau), including 6 upregulated proteins (APP, Aβ1-42, pTauS214, total tau, pTauS404, and pTauS396) (Fig. 2B) and 6 downregulated proteins (neurogranin (NRGN), neprilysin, BACE1, PSEN1, IDE, APOE) (Fig. 2C) in the plaque-bearing versus plaque-free regions.