Ling et al (17) blocked the expression of MT1-MMP, a cell surface activator of MMP-2-pro in glioma, by small interfering (si)RNA transient transfection in U251MG, and found that the VM formation was significantly impaired and that the activity of MMP-2 in the MT1-MMP siRNA group was significantly decreased. The gene discussed is MMP2; the disease is glioma.