In mouse models of breast cancer, macrophages contribute to tumor progression through a variety of mechanisms including IL-10 and arginase 1 (Arg1)-mediated immunosuppression, MMP 7/9 and CCL18-induced matrix remodeling, and EGF and TNFα-stimulated tumor cell migration and metastasis [5–7]. The gene discussed is CCL18; the disease is neoplasm.