In contrast, while MT1-MMP alone induced COS-1 cell invasion into collagen matrices, MT3-MMP, which is ineffective type I collagenase, suppressed MT1-MMP-dependent collagen invasion upon co-expression (Fig. 5A), a result consistent with the conclusion that MT3-MMP interfered with the collagen-invasive activity of MT1-MMP in melanoma cells. Here, MT3 is linked to melanoma.