SMAD2 and neoplasm: Our results revealed that sja-let-7 mimics led to a significant downregulation of TGF-β, TGF-βR1, and SMAD2, while the antagonist SMAD7 was upregulated, suggesting that the anti-tumor effects of sja-let-7 may involve modulation of the TGF-β/SMAD pathway (Figure 4J).