CLDN2 and nasopharyngeal carcinoma: To explore the expression profiles of the tight junction proteins claudin-2, − 5, − 8 and − 9 in nasopharyngeal carcinoma, IHC (immunohistochemical analysis), Western blot and real-time PCR were used to detect the expression profiles of these claudin proteins in nasopharyngeal carcinoma tissues and in non-neoplastic mucosal tissues.