NOS2 and atherosclerosis: The precise macrophage subtype responsible for senescent cell clearance in atherosclerosis is unclear, but tissue macrophages expressing the leukocyte integrin CD11d+ clear senescent cells in the spleen.29 CD11d expression was increased in GCV-treated ApoE→p16 mice (which express p16-3MR in vessel wall-derived cells) against all the other groups, while expression of CD11b and the M1 and M2 macrophage markers NOS2 and ARG1 respectively were similar in all mice (Supplementary material online, Figure S9).