TGFB1 and Duchenne muscular dystrophy: Exposure to recombinant TGFβ (20 ng/ml) in the culture medium for 5 h and 24 h led to nuclear accumulation of pSMAD2/3 quantified as a percentage of pSMAD3 fluorescence at 24-h treatment in both DMD and control hiPSC-derived myotubes.