SMAD7 and neoplasm: Given the well-established connection between the TGF-β/SMAD signaling pathway and cell proliferation [11], our findings indicated that sja-let-7 mimics not only downregulate TGF-β, TGF-βR1, and SMAD2 but also upregulate the antagonist SMAD7, suggesting a potential involvement of the TGF-β/SMAD pathway in regulating sja-let-7/Col1α2 axis, which may contribute to anti-tumor activities.