In order to pre-clinically investigate the effect of potential therapies in ALL in a supportive microenvironment, we have developed a real-time murine xenograft model of patient-derived BCR-ABL-positive ALL.24 Six weeks of treatment with ABT-737 led to a significantly slower rate of leukaemic progression and associated prolonged survival compared with vehicle treated mice. The gene discussed is ABL1; the disease is acute lymphoblastic leukemia.