siRNAs targeting MT1-MMP reduce protein levels and MMP-2 activity on gelatin zymography. (A) Invading HT1080 cells lysates were prepared for Western blot analysis and probed for MT1-MMP and Lamin A/C to demonstrate siRNA efficiency and specificity. Actin was used as a loading control. (B) Conditioned media from siRNA-treated HT1080 cells were collected after 48 hours of invasion and gelatin zymography was performed. Arrows denote pro-MMP-9, and pro- and active forms of MMP-2.