MMP9 and cancer: In vitro study of BGC-823, MGC80-3, SGC-7901, and HGC-27 human gastric cancer cells has elucidated that interaction between HMGB1 secreted by the cancer cell-derived exosomes and toll-like receptor 4 (TLR4) on neutrophils fosters the formation of the autophagosome, inhibition of ROS production, and upregulation of MMP9 and VEGF in neutrophils, inducing polarization of neutrophils, promoting cancer cell migration (158).