The target site of β1/6 integrin siRNA was specific to β1 integrin gene. Site-specific mutagenesis primers were designed around the target site of the β1/6 siRNA. Co-transfections of β1/6 siRNA and either wild type β1 integrin or β1 integrin codon-swapped mutant were performed. (A): Western blot analysis of β1 integrin and MT1-MMP expressions, and the effects on MMP-2 activation were examined by zymography in MCF-7-MT1 cells (B). (C): MCF-7-MT1 cells were treated with Col I (100 µg/ml), Con A (10 µg/ml) or TPA (100nM) after β1/6 siRNA transfection. Conditioned medium was collected and effects on MMP-2 activation were examined by zymography. Semi-quantitative densitometry was performed using the Image J 1.46 program (NIH) and is expressed in percent of area.