This was previously demonstrated with MMP-13 in the human squamous cell carcinoma xenografts [33], and with MMP-1 in the human breast carcinoma cell line MDA-MB-231 in the mammary fat pad xenograft model [34], and recently in the MMP-1a knockout mouse, which has significantly decreased lung tumor growth and angiogenesis [35]. Here, MMP1 is linked to squamous cell carcinoma.