TGFBR1 and recessive dystrophic epidermolysis bullosa: When the treatments were normalized to the cells exposed to the vehicle alone, and to those treated with TGF-β1 as a stimulated control, there was a significant decrease in the mean luciferase signal obtained from the TGF-β1-Alk5/Smad2/3 construct in the fibroblasts from the three RDEB patients (Figure 3A,B and Figure S1 for losartan).