Based on our results that collagen I upregulates expression and deposition of fibronectin, which promotes its own expression in mammary epithelium49, and MT1-MMP, which functions broadly in the proteolytic processing of ECM, cell surface, and soluble substrates57, it is therefore tempting to speculate that a collagen-induced mesenchymal shift could initiate feed-forward mechanisms to drive tumor invasion. Here, FN1 is linked to neoplasm.