APOE and atherosclerosis: The apolipoprotein E (ApoE) and LDL receptor (Ldlr) knockout mouse models of atherosclerosis have elevated plasma cholesterol levels when fed a high-fat diet (and on a chow diet in the case of ApoE−/−) due to impaired lipoprotein clearance as a result of ligand (ApoE) or receptor (LDLR) deletion [13].