Assessment of TNF-α production by mouse colonic epithelial cells. TNF-α concentration was measured in cell media after 24 h incubation with 20 μg/mL of LPS, 1 mmol/L of apocynin (Apoc), 20 μg/mL LPS + 1 mmol/L Apoc or without stimulation; aP < 0.05, DSS-induced colitis groups in all subgroups vs control; cP < 0.05, untreated vs LPS treated subgroup in the chronic DSS-induced colitis group; eP < 0.05, LPS vs LPS + apocynin treated subgroup in both DSS-induced colitis groups. Values are presented as mean ± SE. Untreated mouse group: n = 12. Both DSS-induced colitis groups: n = 8.