Figure 8: Contribution of MMPs to ECM degradation. MDA-MB-231 cells were cultured on collagen-coated substrates. After 24 hours, the supernatant was collected and the activity of MMPs evaluated using gelatin zymography. (A) Blots are representative of three independent experiments. Both MMP-2 and MMP-9 activity increased with increase in ligand density (**p < 0.001). (B) MDA-MB-231 cells were cultured on 10 μg/cm2 collagen-coated surfaces in the presence of 5 μM GM6001 or 5 μM blebbistatin. After 24 hours, the supernatant was collected and the activity of MMPs evaluated using gelatin zymography. The activity of both MMP-2 and MMP-9 were significantly reduced in drug-treated cells (*p < 0.05). (C) High magnification (40x) images of cortactin/MT1-MMP co-localization in control and drug-treated cells. Scale bar = 50 μm. (D) Number of active invadopodia, i.e., number of co-localized cortactin/MT1-MMP dots, was significantly reduced in GM6001-treated and blebbistatin-treated cells. Bars indicate statistical significance (*p < 0.001).