AHR and lung disorder: The most well-known AHR antagonists are 3′methoxy-4′-nitroflavone (MNF) [94] and resveratrol [95], Recently, AHR activation has been shown to upregulate the expression of mucin SAC (oligomeric mucus/gel-forming (MUC5AC)) in the airway epithelial cell line via formation of ROS [196], which, in turn, contributes to lung diseases, such as COPD [197].