SULF1 and hepatocellular carcinoma: Evidence has been demonstrated that downregulation of SULF1 in multiple cancers including ovarian, breast, gastric, and hepatoma is orchestrated by DNA hypermethylation of CpG islands which located within promoter or exon 1 A to prevent the transcription factors from binding to their DNA binding sites (Lai et al., 2004b; Lai et al., 2004a; Staub et al., 2007), concluding that epigenetic modulation was crucial for SULF1 silencing in cancer cells.