Measurement of anti-CLDN1 MAb binding to cellular CLDN1 by cell ELISA. After fixation, Huh7.5.1-8 cells in 96-well plates were incubated with serial dilutions of each anti-CLDN1 MAb (2C1, 3A2, 5F2, and 7A5) or control IgG, followed by horseradish peroxidase-conjugated second antibody. The binding of each antibody to cellular CLDN1 was measured as described in Materials and Methods.