FIG 3.

Effects of claudin-1 or -4 ECL-2 peptides when added after CPE. Confluent Caco-2 cells, grown in different cell culture plates, were treated with 0.5 μg/ml of CPE and incubated for 10 min at 37°C. After that incubation, CPE was taken out from two of the plates, and a 400-fold molar excess of claudin-4 ECL-2 peptide or a 400-fold molar excess of claudin-1 ECL-2 peptide was added to each of the plates. CPE was not removed from the other two plates before the same amount of each peptide was added. All plates were then incubated further for 50 min at 37°C. For the control experiments, confluent Caco-2 cells were treated for 1 h at 37°C with (i) 0.5 μg/ml CPE, (ii) claudin-4 ECL-2 peptide only, (iii) claudin-1 ECL-2 peptide only, and (iv) HBSS buffer only. Supernatants from all the treatments were collected, and cytotoxicity was measured using the cytotoxicity detection kit (Roche).