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). This evidence concerns the gene SMAD2 and Bloom syndrome.