Ichinose et al. reported that PGA and PGC genes are hypomethylated in tissues producing PGA and PGC, which suggests a role for DNA methylation in the regulation of their differential expression during normal differentiation.133,134) In gastric cancer tissues and cancer cell lines, no gross structural changes of the pepsinogen genes were observed, but the methylation patterns of the pepsinogen genes were found to be altered in different ways in various cancers. This evidence concerns the gene PGC and cancer.