SMAD3 and atrial fibrillation: The TGF‐β signalling pathway is one of the central regulatory systems in cardiac fibrogenesis,23, 24 and c‐Ski has been identified as an inhibitor of TGF‐β signalling, which functions through its interaction with Smad proteins.9, 25 Here, we observed that c‐Ski overexpression decreased the phosphorylation of smad2 and smad3 and the expression of TGF‐β1 in atrial tissues, based on a comparison of the levels in the AF‐Adc‐Ski group to those in the AF‐control and AF‐AdNull groups.