MMP9 and breast cancer: NF-κB signaling pathway is constitutively activated in breast cancer, and has been shown to contribute to the development and progression of tumors.33 Several genes involved in angiogenesis, invasion and metastasis, such as VEGF, uPAR, MMP9, COX-2 and ICAM-1, have been identified as being regulated by NF-κB.34, 35, 36, 37, 38 The frequent activation of NF-κB in breast cancer cells suggests that breast tumor cells may acquire metastatic activity by overexpression of metastasis relevant genes during their progression.