MMP9 and neoplasm: Consistent with the IHC results, we observed that lungs from mice bearing triple-negative SUM159 primary tumors showed increased expression of murine fibronectin, tenascin-c, periostin, MMP9 and collagen A1 compared to lungs from mice bearing luminal A MCF7 primary tumors or age-matched tumor-naïve mice (p ≤ 0.05) (Figure 4a–e).