Meanwhile, there are at least dual mechanisms mediated the inhibition of CYP2J2/EET on atrial fibrillation via activating PPAR‐γ (Figure 6D); on the one hand, CYP2J2/EET reduced atrial fibrosis through modulating atrial fibroblasts by eliminating the inhibition of MiR‐21 on Smad‐7; on the other hand, CYP2J2/EET ameliorated atrial inflammatory response by repressing NF‐κB pathways. The gene discussed is SMAD7; the disease is atrial fibrillation.