Recent experimental data also show that elevated expression of MMP-1 promotes not only breast cancer growth at the primary site (orthotopic injection model) but also brain and lung metastases (left ventricle of the heart and tail vein injection model) through activation of epidermal growth factor receptor (EGFR) signaling by MMP-1-proteolyzed-active TGFα [27]. Here, EGFR is linked to breast cancer.