PCGF2 and gastric cancer: We found that gastric tumor tissues expressed significantly higher Bmi-1 and lower Mel-18, and the expression of Mel-18 negatively correlated with Bmi-1; there was a significant positive correlation between Bmi-1 expression with lymph node metastasis, or clinical stage, but there was no obvious correlation between Mel-18 expression and clinicopathological factors; downregulation of Bmi-1 by Mel-18 overexpression or knockdown of Bmi-1 expression was accompanied by decreased transformed phenotype and migration ability in gastric cancer cell lines in in vitro study[33].