MMP9 and gastric cancer: In the present study, a subcluster of neutrophils with high-activity phenotypes accounted for a major proportion of PB samples after treatment, which also highly expressed well-known tumor-promoting genes of gastric cancer including MMP9, S100A8, S100A9, PORK2, and TGF-β1 (Verma et al., 2015; Zhang et al., 2018; Sprenkeler et al., 2022).