To test this possibility, migration assays with the RAW264.7 macrophage cell line were performed using CM from (1) the Stat1−/− tumor cell line SSM2, (2) the Stat1+/+ normal MECs (EpH4, EpH3) and the polyoma middle T-induced mammary tumor cell line Met1, and (4) the Neu-induced mammary tumor cell line NDL. Here, STAT1 is linked to breast cancer.