TGFB1 and atrial fibrillation: Proliferation and migration of human dermal fibroblasts and in vivo wound healing were improved in the CMs derived from AF-MSCs exposed to selenium and bFGF, which was caused by the Smad2, AKT-MEK1/2-ERK, and NFκB signaling triggered by the paracrine factors of AF-MSCs, such as TGF-β, VEGF, and IL-6.