According to our criteria to determine CDO1 methylation in cell lines and tissues by bisulfite-sequencing (described in Materials and Methods), the frequency of CDO1 methylation in tumors was 100% (21/21) and that in normal methylation was 0% (0/21), indicating that CDO1 is hypermethylated in CRC (Fig. 1B). This evidence concerns the gene CDO1 and colorectal carcinoma.