Immunohistochemical evaluation was carried out to identify CLDN4 using anti-CLDN4 antibody, 4D3. CLDN4 was visualized by peroxidase-diaminobenzidine (DAB) method (left column) or Cy5-labeled secondary antibody (right column). Cy5 images were semi-quantified for evaluation of CLDN4 protein levels. (A) non-cancerous tongue epithelium (B) OSCC, G2, pT2pN0pM0, (C) OSCC, G2, pT3pN1pM0, (D) OSCC, G3, pT4PN2pM0. Bar, 100 μm.