MUC4 and gastric cancer: For example, MUC1 and MUC5AC affect E‐cadherin and β‐catenin complexes, thereby promoting the proliferation, invasion, and metastasis of ovarian and gastric cancer cells [15, 16]; in contrast, MUC4 gene deletion in pancreatic cancer cells inhibits tumor progression by regulating apoptosis and cell cycle [32].