POU4F1 and renal fibrosis: By using single cell RNA sequence analysis, we reveal that TGF-β1 induces MMT in bone marrow-derive macrophages via the Smad3-Src-POU4F1 pathway as Smad3 can bind Src and POU4F1 promoters to induce MMT and targeting this pathway can block MMT and renal fibrosis in vitro and in vivo30, 33.