The chemokine monocyte chemoattractant protein-1 (MCP-1)/CCL2 is a potent chemoattractant for monocytes and has been shown to play an important role in the recruitment of immunosuppressive, proangiogenic tumor-associate macrophages (TAMs) and the promotion of lung metastasis of breast cancer cells [6,7]. Here, CCL2 is linked to breast cancer.