Aberrant DNA methylation of promoter region CpG islands of several genes, including retinoblastoma (Rb), von Hippel-Lindau (VHL), p16, p15, APC, E-cadherin and hMLH1 has been reported in human cancers, and silencing of hMLH1 by promoter hypermethylation is the major causative event in the development of human cancers with MSI phenotype, including gastric cancers (Graff et al, 1997; Kane et al, 1997; Herman et al, 1998; Fleisher et al, 1999; Kang et al, 1999; Leung et al, 1999; Suzuki et al, 1999; Tamura et al, 2000; Tsuchiya et al, 2000). Here, RB1 is linked to cancer.