CXCL9, also referred to as monokine induced by IFN-γ (MIG) and induced by IFN-γ [21], appeared to be the highest overexpressed molecule among the CXCL9, -10, −11/CXCR3 axis found in the primary breast cancer samples that developed brain metastasis (Fig. 6). This evidence concerns the gene IFNG and breast cancer.