Forced expression of Smad3, similar to TGF-β1 treatment, led to the repression of SLC7A11 expression in HCC cells, and additional treatment of TGF-β1 was able to enhance the repression, indicating that TGF-β1 suppressed expression of SLC7A11 via Smad3. This evidence concerns the gene TGFB1 and hepatocellular carcinoma.