The elevated claudin-1 expression induced by 5-fluorouracil (5-FU) or TNF-α treatment is associated with the regulation of apoptosis in nasopharyngeal carcinoma and pancreatic cancer cells, although these cells low levels of protein expression and claudin-1 localization in the membrane were also observed [23,24]. The gene discussed is TNF; the disease is nasopharyngeal carcinoma.