Effect of PFOA on the expression levels of tight junction gene Cldn in intestinal tissues of CD1 mice. Mice were treated with control (0.5% Tween-20 in water) or 1–20 mg/kg/day PFOA for 10 days. (A) Change in the mRNA expression level of Cldn2, Cldn3, Cldn4, Cldn7, Cldn8, Cldn12, and Cldn15 genes in the small intestine; (B) change in the mRNA expression level of Cldn2, Cldn3, Cldn4, Cldn7, Cldn8, Cldn12, and Cldn15 genes in the colon. Statistical values were considered significant at p-value ≤ 0.05 (denoted by “*”) and less significant at p-value > 0.05 but < 0.1 (denoted by “^”) reported from two-tailed tests.