Immunohistochemical demonstration of claudin protein expression in human gastric cancer and adjacent tissue. Claudins were expressed in the cell cytoplasm and membrane. ( A ), claudin-2 was highly expressed in epithelial cells adjacent to gastric cancer but was expressed at low levels in cancer tissue itself ( B ). ( C ), the strong expression of claudin-6 in tissue adjacent to human gastric cancer compared to low expression of claudin-6 in human gastric cancer tissue ( D ). ( E ), low claudin-11 expression was detected in tissue adjacent to human gastric cancer compared with high claudin-11 expression in human gastric cancer tissue ( F ) (400×).