CCR2 and neoplasm: Among the two main subsets of circulating monocytes, non-classical monocytes (CCR2- CX3CR1highLy6Clow in mouse, CCR2- CX3CR1highCD14dimCD16+ in humans) are also called patrolling monocytes (PMo) by their ability to actively patrol the vascular endothelium to search for harmful microparticles (pathogens, circulating tumor cells, amyloid deposits, abnormal red blood cells, etc.)or dying endothelial cells and promote their removal to restore homeostasis (1–5).