Effect of DON on trans-epithelial electrical resistance (TEER) of differentiated IPEC-J2 cells. Cells were grown for 21 days on Transwell® collagen-coated PTFE filters (0.33 cm2, 0.4 μm). Next, at day 0 various concentrations of DON were added to the apical compartment for 72 h: untreated inserts, inserts treated with 0.5, 1, 5 or 10 μg/ml of DON. TEER values are expressed as mean + stdev (n = 3) . Significant differences in TEER value have been marked with *** (P < 0.001).