To determine whether Vav3 and Bmi1 interaction modulates the PRC1 activity and p190-BCR-ABL-induced B-ALL progression, we co-transduced WT and Vav3−/− low-density bone marrow cells (LDBM) with p190-BCR-ABL (plus EYFP) and Bmi1 (plus EGFP) bicistronic integrating vectors, and then transplanted them into lethally irradiated congenic female mice to monitor leukemogenesis (Fig. 4a). Here, BMI1 is linked to precursor B-cell acute lymphoblastic leukemia.