Relapsed MPD-like AML is transplantable but requires a longer latency for disease induction. (A) BM cells from secondary recipient mice with MPD-like AML (after chronic or temporary Dox treatment) were transplanted into tertiary recipient SCID mice. As a control, BM cells from previously transplanted AML (not treated with Dox) were intravenously injected into control SCID mice. (B) Kaplan-Meier survival curve shows that the SCID recipients of BM from relapsed MPD-like AML cases have significantly longer survival time in comparison with those mice transplanted with AML that were never treated with Dox (P < .001). (C) Western blot analysis of spleen cells shows that the NRAS^G12V transgene is expressed again in the engrafted AML after BM transplantation with the relapsed MPD-like AML that has been treated with Dox for 6 hours, but not with chronic Dox treatment. Circled numbers over each lane indicate each protein sample from tertiary recipient mice with (1) AML engraft without Dox treatment; (2) AML regression after 4-day Dox treatment; (3) AML relapse after 6-hour Dox treatment; (4) AML engraft without Dox treatment after relapsed AML (with 6-hour DOX) transplantation; (5) AML relapse with chronic Dox treatment; (6) AML engraft after relapsed AML (with chronic Dox) transplantation; and (7) TM-transgenic AML.