Comparative expression levels of Bmi-1 or Mel-18 were shown in 71 normal mucosal tissues and paired gastric cancer samples. A: Bmi-1 gene expression in human gastric cancer. B: Mel-18 gene expression in human gastric cancer. Expression level of target genes was displayed in a relative quantification method as a ratio between it in tumor tissues and that in normal tissues in the amounts of RNA. The expression level of Bmi-1 or Mel-18 in normal tissues was treated as 1 and the ratio of gene expression was the expression level of Bmi-1 or Mel-18 in tumor tissues.