As shown in Figure 5A–D, the increased expressions of TGF‐β1 and p‐Smad2/3 induced by TAC were significantly reduced following rAAV9‐POSTN‐miR‐425‐5p administration, suggesting that the antifibrotic activity of miR‐425‐5p is closely associated with the suppression of TGF‐β1/Smad signalling. The gene discussed is TGFB1; the disease is persistent truncus arteriosus.