PTEN and lung cancer: Recent studies suggest that in some cancer cell lines polycomb‐group protein BMI‐1 negatively regulates PTEN expression and promotes cancer progression due to increased activity of AKT.3, 5, 16 BMI‐1 depletion was shown to cause EMT inhibition in nasopharyngeal and melanoma cells.3, 17 BMI‐1 promoted also invasion and metastasis of hepatocellular carcinoma and pancreatic cancer stem cells.4, 5 However, in contrast to that Xiong et al18 indicated that low BMI‐1 expression might contribute to the metastasis of lung cancer.