Bone marrow-derived mesenchymal stem cell (BMSC) exosomes loaded with miR-29b-3p inhibited fibroblast activation by targeting frizzled-6 (FDZ6), a receptor of the wingless-type mouse mammary tumor virus integration site family member 4 (Wnt4) ligand critical for cell differentiation in the mouse idiopathic pulmonary fibrosis (IPF) model (Fig. 2E and F) [46]. Here, WNT4 is linked to pulmonary fibrosis.