To investigate changes in the distribution and expression of LSR and CLDN-2 during carcinogenesis of human lung adenocarcinoma, immunohistchemical staining for LSR and CLDN-2 was performed using paraffin-embedded sections of lung cancer tissues (8 different adenocarcinomas, 2 invasive, 3 papillary, 1 acinar, 2 solid). The gene discussed is CLDN2; the disease is adenocarcinoma.