NOS2 and atherosclerosis: To investigate whether macrophage polarization switch was involved in the role of Rb1 on atherosclerosis, immunofluorescent analysis of iNOS and Arg‐I expression was applied to identify and evaluate, respectively, M1 and M2 macrophage (MOMA‐2 + cells) in aortic root cryosections from Rb1 and control group.