Quantitative DNA methylation analysis showed that the promoter of the SLC22A1 gene is often hypermethylated in hepatocellular carcinoma (HCC), as compared to the matched normal adjacent liver tissues of Caucasian patients, resulting in a significantly lower OCT1 protein level, assessed by immunohistochemistry, in HCC than in the normal liver [75]. The gene discussed is SLC22A1; the disease is hepatocellular carcinoma.