In a previousin vivo study, CCL2-induced chemokine cascade in macrophage-associated metastasis (MAM) produced another ligand, CCL3, for metastatic seeding of breast cancer cells7,10 In addition, IL18 plays a role in the migration of breast cancer cells via down-regulation of claudin12 and p38 MAPK (mitogen activation kinase) pathway11. Here, CCL2 is linked to breast cancer.