MMP9 and cancer: In cancer, polarization of TANs has been shown to play an important role in the immune response: N1 neutrophils are considered inflammatory, express high levels of Tnf and restrain tumorigenesis through cytotoxicity and enhancement of anti-tumor responses while N2 neutrophils, which strongly express genes such as Mmp8 and Mmp9 are thought to stimulate tumor growth by promoting remodeling of extracellular matrix, enhancing angiogenesis, and inhibiting cytotoxic T-cell responses [31–33].