MMP9 and breast cancer: Knowing that change in ECM expression and matrix metalloproteinase (MMP) participates in cancer cell metastasis and SERPINE2 enhances pancreatic tumor invasion [37] and lung metastasis of breast cancer via producing ECM and secreting MMP-9 [38], we next detected the expression of EMT markers (E-cadrin, N-cadrin, VIM and Snail) and MMP-9.