Several studies of tumors, including gastric adenocarcinomas [18,19], esophageal squamous cell carcinomas [20,21], colorectal cancers [22,23], and breast cancers [24], reported that methylation status of the RKIP promoter determined by MSP (methylation specific PCR) strongly correlated with low RKIP expression levels in various advanced stages of the tumors. The gene discussed is PEBP1; the disease is breast cancer.