SMAD7 and Bloom syndrome: The expression levels of TGFβR1, TGFβR2, TGF-β1, TGF-β2, TGF-β3, Smad2 and Smad3 gradually increased from the 7th to the 28th day of BLM induction, while the expression levels of Smad6 and Smad7 decreased (Figure 3E).