Immunohistochemical analysis of premetastatic niche markers indicated that, relative to mice bearing luminal A MCF7 primary tumors or age-matched tumor-naïve controls, mice bearing triple-negative SUM159 primary tumors demonstrated enhanced expression of fibronectin, tenascin-c, periostin and MMP9 in the lung (Figure 3). This evidence concerns the gene POSTN and neoplasm.