SMAD3 and Bloom syndrome: As shown in Figure 6, the expression levels of TGF-β1, TβRI, TβRII, p-Smad2, and p-Smad3 protein in the lung tissue of the BLM group mice were significantly higher than those in the NC group (P < 0.01), and the expression level of Smad7 protein was significantly lower (P < 0.01).