Atherosclerosis in non-Ang II–infused 8-month-old male ApoE^–/–OPN^+/+ and ApoE^–/–OPN^–/– mice. (a) En face analysis of aortic atherosclerosis in 8-month-old ApoE^–/–OPN^+/+ and ApoE^–/–OPN^–/– mice on a regular chow diet. (b) Mean atherosclerosis development in the total aorta from ApoE^–/–OPN^+/+ (black bar) and ApoE^–/–OPN^–/– (white bar) mice analyzed as described in Figure 1.