CLDN7 and gastric cancer: Downregulation of CLDN7 has been linked to breast cancer as well as invasiveness of both endometrial cancer and esophageal squamous cell carcinoma [38,112,113,114], while the upregulation of CLDN7 has been found in ovarian cancer, chromophobe renal cell carcinoma, and gastric cancer [17,115,116,117,118].