MMP9 and breast carcinoma: Numerous tumor-derived cytokines including granulocyte macrophage colony-stimulating factor (GM-CSF), thymic stromal lymphopoietin (TSLP), matrix metalloproteinase 3 (MMP-3) and matrix metalloproteinase 9 (MMP-9) have been reported to contribute to breast cancer progression [9,10,11].