Biomarkers such as claudin 18.2 (CLDN 18.2), human epidermal growth factor receptor 2 (HER2), mucin 1, natural-killer receptor group 2 (NKG2D), epithelial cell adhesion molecule (EpCAM), mesothelin (MSLN) and carcinoembryonic antigen (CEA) play important roles in the diagnosis and function of gastric cancer (56). This evidence concerns the gene ERBB2 and gastric cancer.