APP and Alzheimer disease: This model has several key features: (1) no familial AD mutations are included and the mouse expresses the wild-type human sequence of the amyloid precursor protein (APP) cleavage product; (2) the endogenous gene-regulatory elements are used so APP is produced at murine physiological levels; and (3) loxP sites flank the exon encoding Aβ allowing for cell-specific/temporal control of Aβ/APP production to enable further cell-specific mechanistic investigation.