Studies have shown that PAD4 can upregulate the expression of CXCR2, KRT14, TNF-α, and the matrix metalloproteinases MMP2 and MMP9, thereby activating the inflammatory response, angiogenesis, and cell proliferation, migration and invasion in tumor tissues, thereby promoting the development and progression of gastric cancer [232,233]. Here, MMP2 is linked to neoplasm.