CCR2 and neoplasm: To reassess the role of Ccr2-mediated monocyte recruitment to lung metastasis, we analyzed the infiltration of Ly6Chi monocytic cells in the lungs of BL6, Ccr1-/- and Ccr2-/- mice, 12- and 24-h post-intravenous tumor cell injection (Fig. 3 A, Supplementary Fig. 3).