To determine whether Rap1a participates in macrophage inflammation in atherosclerosis, immunofluorescence staining showed that more Rap1a-positive cells co-localized with F4/80 in the aortic plaque of ApoE−/− mice fed a high-methionine diet than in that from ApoE−/− mice fed a regular diet (Fig. 4B). This evidence concerns the gene APOE and atherosclerosis.