We analyzed F2 progeny from a cross between apolipoprotein E-null mice on DBA/2J (DBA-apoE) and C57BL/6J (B6-apoE) genetic backgrounds Apoe-null mice on DBA and B6 backgrounds were obtained from the Jackson Laboratory (Bar Harbor, ME, USA). Male DBA-apoE mice were mated to female B6-apoE mice to generate F1 progeny. F1 hybrids were intercrossed to generate the F2 population. F2 mice (136 females and 96 males) aged 4.5 months were used for analyses in this study. Sizes of atherosclerotic plaques in the aortic root and the aortic arch were measured as described previously (Tomita et al, 2010; Zhang SH et al 1992). Briefly, mice were euthanized with a lethal dose of 2,2,2-tribromoethanol followed by cervical dislocation, and perfused with 4% paraformaldehyde through the left ventricle of the heart. The plaque areas in the defined locations of the aortic arch (FigS1) were measured using images captured with Image J software. The plaques at the innercurve of the aortic arch were used to represent “arch plaque size”. Lesion sizes (in micrometers squared) at the inner curvature of aortic arch and at the aortic root were subject to square root transformation to achieve an approximately normal data distribution.