Generation of isogenic leukemia cells to test the effects of inducing the 5A3 deletion in established AMLs. (A) Overview of the experimental protocol used to induce the 5A3 deletion in established AMLs from MOL4070LTR treated Mx1-Cre, 5A3^fl/+ mice. Primary leukemias were isolated from mice that had been injected with MOL4070LTR and pIpC, and transplanted into sublethally irradiated recipients. These recipients received a high-dose pIpC regimen beginning 10 days after transplantation, and leukemic cells were subsequently analyzed by Southern blotting to assess 5A3 recombination. Secondary leukemias that showed balanced ratio of recombined versus unrecombined cells were then reinjected into sublethally irradiated recipients that were treated with Ara-C and doxorubicin as described in “Treatment with doxorubicin and Ara-C” and monitored for survival. (B) Southern blot analysis of BM DNA from the primary mice nos. 18 and 102 (P) and recipients of these leukemias (TP). Note enrichment of the 20-kb recombined fragment in BM DNA from transplant recipients that were treated with high-dose pIpC (HD). (C) Southern blot analysis of BM DNA from the recipients of leukemia no. 18 after treatment with chemotherapy (T) or vehicle (V). (D) Kaplan-Meier survival curve of mice that received a transplant of a no. 18 leukemia that has 50% recombined and 50% unrecombined leukemic cells. (E) Kaplan-Meier survival curve of mice that received a transplant of a no. 102 leukemia that has 50% recombined and 50% unrecombined leukemic cell.