Prior to deciphering the mechanism underlying IFN-γ-induced cancer metastasis, we first verified the pro-metastatic effect of IFN-γ in five cell lines of different human cancers (Figure 1A): the kidney cancer cell line Caki-1, the lung cancer cell line A549, the cervical carcinoma cell line CaSki, the breast cancer cell line BT549, and the colon cancer cell line HCT116. The gene discussed is IFNG; the disease is breast carcinoma.