TGFB1 and atrial fibrillation: Furthermore, studies utilizing human AF samples, TGF-β-treated human atrial endocardial endothelial cells (AEECs), and cardiac-specific TGF-β transgenic mice have demonstrated that miR-181b ameliorates AF fibrosis by suppressing the TGF-β-induced endothelial-to-mesenchymal transition (EndMT) (106).