MMP9 and gastric cancer: MG7‐Ag is a kind of GC‐specific tumor‐associated antigen, which increases in GC and precancerous lesions.23, 24 Recent studies have suggested that MG7‐Ag could be considered an important early warning molecule of gastric cancer.25 MMP9, also termed as Gelatinases B, belongs to the matrix metalloproteinases (MMPs) family.