The hypermethylation in the CXCL12 promoter region in more than 50% of breast tumors was detected by methylation-specific PCR, and the expressions of DNMT1 and DNMT3b were distinctly higher in CXCL12-methylated breast cancers than in CXCL12-unmethylated breast cancers (Zhou et al., 2009). This evidence concerns the gene DNMT1 and breast cancer.