CD9 and gastric cancer: Miki et al. (2018) revealed that CD9-positive EVs from CAFs were taken into scirrhous-type gastric cancer cells. MMP-2 expression in scirrhous-type gastric cancer cells was significantly decreased by CD9-siRNA. CD9 positivity was significantly related to LN metastasis and venous invasion. MMP-2 is well known as a modulator of dynamic remodeling of the ECM (Quintero-Fabián et al., 2019).