As MCP-1 mediated activation and migration of monocytes plays a central role in the initiation of atherosclerosis[26] as well as in the development of restenosis after angioplasty[27], the proinflammatory stimulation of endothelial cells by heterodimeric S100A8/S100A9 protein may thus represent a hitherto unknown critical mechanism in the early propagation of atherosclerosis. Here, S100A9 is linked to atherosclerosis.