CCL2 expression increases with neoplastic progression in both human and mouse models of colitis‐associated colorectal cancer.53 In PyMT mice bearing mammary tumors, classical Ly6Chi monocytes are recruited in a CCL2‐dependent manner to both primary tumors and pulmonary metastases.2, 48 A similar pattern of recruitment occurred for CD14+CD16– monocytes adoptively transferred into nude mice, suggesting that classical monocyte recruitment is a feature of both mouse and human tumors.2 Here, CCL2 is linked to breast cancer.