CLDN1 and hepatocellular carcinoma: In regard to the TJ proteins, CLDN-1 protein was detected only in HCV-resistant PM1 T cells (∼30% of the signal displayed by Huh7.5 cells) and in HepG2 hepatoma cells (∼170% of the signal identified in Huh7.5), and at a lower level (∼25%) by control HEK-293 cells transfected with CD5 (Figs. 3A and 3B).