Transforming growth factor (TGF)-β1 has been shown to induce the demethylation of PROM1 promoter P1 by inhibiting the expression of DNA methyltransferase-1 and 3β (DNMT1 and DNMT3ß) in hepatoma cells, leading to a significant upregulation of CD133 [121]. This evidence concerns the gene DNMT1 and hepatocellular carcinoma.