MMP9 and gastric cancer: Immunofluorescence staining on pairs of metastatic lymph nodes and primary tumors from 36 GC patients showed that the expression of eCAF markers MMP9, COL1A1, and Fibronectin was significantly higher in metastatic lymph nodes than in primary tumors, which was positively correlated with EGR4 level (Fig. 6G–I).