APOE and atherosclerosis: The differences in severity of atherosclerosis phenotypes between chow-fed Apoe−/− mice and Ldlr−/− mice are most likely due to the elevated levels of TRLs and RLPs in Apoe−/− mice, as compared with Ldlr−/− mice, which in turn is due to the severely impaired hepatic clearance of APOE-containing TRLs and RLPs in Apoe−/− mice.