The additional knockout of ApoE does not affect the Aβ levels in Ldlr-deficient AD mice (APP/PS1; Katsouri and Georgopoulos, 2011), and this was confirmed by an in vitro study in astrocytes demonstrating that the clearance of Aβ is independent of ApoE (Basak et al., 2012). Here, APP is linked to Alzheimer disease.