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). The gene discussed is ABL1; the disease is precursor B-cell acute lymphoblastic leukemia.