MAPK3 and gastric adenocarcinoma: More importantly, many reports indicated that the ERK1/2 pathway was closely correlated with tumor invasion and metastasis: p-ERK1/2 expression was closely correlated with metastasis of gastric adenocarcinoma, and enhanced p-ERK1/2 activity could significantly enhance the invasion and metastasis of gastric adenocarcinoma cells [19].