MUC5AC and gastric cancer: The virulence factor urease and the effects of H. pylori on the expression and transcription levels of MUC in MUC genes (MUC5AC, MUC2, and MUC6) in gastric mucosa of Kato-III may upregulate the expression of chemokines and proinflammatory factors while downregulating the transcription of the MUC5AC gene in GC cells.