SMAD4 and idiopathic pulmonary fibrosis: In conclusion, our study showed the role and mechanism of the TGF-β1/Smad4-Hoxaas3–miR-450b-5p–Runx1 axis for a better understanding of PF (Fig. 8g), and demonstrated Hoxaas3 maybe a new diagnostic biomarker or potential therapeutic target for IPF.