In the current study, primary tumor MMP-9 and VEGF levels confirmed the macrophage polarization from M1 to M2 and establishment of an immune suppressing/tumor-supporting microenvironment in 4T1 + RAW264.7 inoculated mice as primary tumors from this inoculation group showed lower MMP-9 and VEGF levels compared to the 4T1 inoculation group at pre-metastasis, but similar levels upon metastasis. This evidence concerns the gene MMP9 and neoplasm.