In vivo effect of ZOL alone and in combination with imatinib mesylate on survival in engrafted mice. Each line represents the survival ratio of 5 groups of mice. Administration of ZOL/imatinib mesylate was initiated on day 8. Mice were divided as follows: (1) untreated mice; (2) mice treated with 80 μg/kg ZOL once a week for 6 weeks; (3) mice treated with 80 μg/kg ZOL 3 sequential days a week for 10 weeks; (4) mice treated with 120 mg/kg/d imatinib mesylate from day 8 to 17; and (5) mice treated with 80 μg/kg ZOL 3 sequential days a week for 10 weeks and with 120 mg/kg/d imatinib mesylate from day 8 to 17. Each group contained 6 mice.