BMI1 and neoplasm: Injection of CD133 + Lenti-BMI1–922 cells resulted in tumor formation of 22.2% (2 of 9 mice) in the IC-1406GBM group and 0% (0 of 7 mice) in IC-2305GBM, which is in agreement with our findings in vitro in the cultured neurospheres (Figure 2A, B).