MMP9 and breast cancer: Down-regulation of MMP2 expression by siRNA inhibited IL-6-induced breast cancer cell migration about 38%(Fig. 1g) and Si-MMP9 inhibited IL-6-induced breast cancer cell migration about 39%(Fig. G), while Down-regulation of both MMP2 and MMP9 expression by siRNA inhibited IL-6-induced breast cancer cell migration about 20%(Fig. G).