Using immunofluorescence and immunohistochemistry analysis of SMA, Iba-1, F4/80 and Ki-67, we found that both the proliferation and recruitment of fibroblasts and macrophages into the tumor was significantly decreased in MDA-MB-231-CXCR2−/− cell tumors compared to tumors generated by wild type MDA-MB-231 cells (Supplementary Figure 3F–3L). This evidence concerns the gene CXCR2 and neoplasm.