When CAFs that were isolated from a human breast carcinoma and a breast cancer cell line (MCF-7) were subcutaneously injected into immunodeficient (nude) mice, growth of the breast carcinoma with CAFs was more rapid compared to that of the breast carcinoma with normal fibroblasts because of elevated secretion of stromal-cell-derived factor 1 (SDF-1) in the former [59]. Here, CXCL12 is linked to breast cancer.