Tumor development and angiogenesis in CCR2^−/− mice. (A) WT (n = 8) and CCR2^−/− (n = 7) mice were inoculated with 5 × 10⁵ or 1 × 10⁵ 3LL cells. (B) WT (n = 8) and CCR2^−/− (n = 9) were inoculated with 5 × 10⁵ B16 cells. Each time point represents the mean (± SD). (C) Cryosections of 8- to 10-mm tumors from CCR2^+/+ or CCR2^−/− mice were subjected to hematoxylin and eosin staining. Representative image from 5 mice for each group. Original magnification, ×50. Whole tumor images were reconstituted with Adobe Photoshop (Adobe Systems, Mountain View, CA). (D) Percentage of necrotic area in the tumors from CCR2^+/+ or CCR2^−/− mice. Graph represents the mean (± SD) of 5 mice. (E) mRNA expressions of MMP9 and VEGF in the tumor of WT and CCR2^−/− mice. Graph represents the mean (± SD) of 4 mice. (F) Cryosections of 8- to 10-mm tumors from CCR2^+/+ or CCR2^−/− mice were stained with antibodies to CD31 (green) and type IV collagen (red). Representative images of non-necrotic area. Original magnification, ×100. (G) Percentage of CD31- or Type IV collagen-positive areas in non-necrotic area. Graph represents the mean (± SD) of 5 mice.