We recently reported that claudin-1 (CLDN1), CLDN2, and occludin, components of tight junctions (TJs), decrease chemosensitivity to doxorubicin (DXR), an anthracycline anticancer drug, in 3D-cultured lung adenocarcinoma A549 cells9,10. This evidence concerns the gene CLDN1 and lung adenocarcinoma.