Because the promoter region of TP73 contains four typical CpG islands (Fig. 3A), we examined their methylation state in genomic DNA isolated from nine cell lines (three normal cells and six HCC & GI cancer cell lines) utilizing methylation-specific PCR (Fig. 3B) and bisulfite sequencing (Fig. 3C). The gene discussed is TP73; the disease is hepatocellular carcinoma.