It is suggested that this cell proliferation is associated with the MMP-epidermal growth factor receptor-mitogen-activated protein kinase-extracellular signal-regulated kinase 1/2 (MMP-EGFR-MAPK-ERK1/2) pathway, and that PAR-2 promoted colon and gastric cancer cell proliferation and invasion through the MMP-EGFR-MAPK-ERK1/2 pathway following activation. Here, MAPK3 is linked to gastric cancer.