Acting through the TGFβ-TGFβR1-SMAD2/3 axis, we found that bleomycin promoted migration of AF cells and BMSCs, and also upregulated the expression of key ECM genes such as type 1 collagen as well as type 3 collagen, FN1 in AF cells [48–50]. Here, FN1 is linked to atrial fibrillation.