ERBB2 and gastric cancer: Nowadays, there are many different signatures that can provide the division of gastric carcinoma by taking in consideration age, histopathological type, Helicobacter pylori infection, microsatellite instability, module of HER2 expression, molecular markers of cell cycle regulators, factors that regulate apoptosis, multidrug resistance proteins, agents that influence cell membrane properties, and agents with an impact on the progression of gastric cancer and peritoneal metastasis.