On the other hand, single fluorescent cells that expressed Bmi1 at the time of tamoxifen injection but did not divide thereafter were observed both at days 7 and 28 after induction in all three models (Fig. 2a,c,e and Supplementary Table 1), indicating that not all Bmi1+ cells in tumors behaved as cancer stem cells. This evidence concerns the gene BMI1 and cancer.