Interestingly, although atherosclerosis development was more progressed in Apoe knockout mouse than in rat (Fig. 2C), AMPCs of Apoe knockout rat in hyperlipidemic artery outnumbered those of mouse (Fig. 3B), which may have contributed to the higher adventitial macrophage population in Apoe-deficient rat than in mouse. Here, APOE is linked to atherosclerosis.