PTEN and cancer: A number of studies have demonstrated that PI3K/PTEN/AKT/mTOR signaling pathway regulates VEGF expression in different types of cancer cells [56, 57], and it was found in previous and present studies that Bmi-1 upregulates AKT activity, so we speculated that Bmi-1 might upregulate VEGF expression via activating AKT, and VEGF might mediate the function of Bmi-1 in inducing angiogenesis.