Claudins 1, 3, 4, 5, 7, 8, and 18 are expressed in human bronchi and bronchioles whereas claudin-6 expression may be an effect of immortalization of the CFBE41o- epithelial cell line as it has been reported in non-small cell lung cancer (31) and in developing lung tissue (32). Here, CLDN6 is linked to non-small cell lung carcinoma.