MMP13 and neoplasm: We speculate that MMP-13 inhibits or disrupts VM formation first by cleaving Ln-5 γ2′ and Ln-5 γ2x into smaller fragments, thus preventing transfer of molecular signals in the ECM from inducing the vascular phenotype of aggressive tumor cells; and second by degrading VE-cadherin on tumor cells which may deter the downstream signal transfer and then abrogate the ability to form vasculogenic networks of tumor cells.