To demonstrate the effectiveness of using our re-programmed leukemic cell lines to validate the efficacy of BH3-mimetic agents in vivo, we transplanted 1 × 105 p185+ B-ALL cells re-programmed to express either human BCL-2 or human MCL-1 into C57BL/6 recipients. The gene discussed is BCL2; the disease is acute lymphoblastic leukemia.