DOX-regulated KLF4 expression depletes BCR-ABL–transformed pre-B cells in vivo. Bone marrow from FVB/N mice that were either nontransgenic or double transgenic for MMTV-tTA and TRE-KLF4 was transduced with BCR-ABL and injected in lethally irradiated FVB/N mice. Recipients were given water with or without DOX. (A, B) Leukemic mouse bone marrow was analyzed for progenitor B-cell markers as in Figure 2D. Percentages are displayed on a representative plot (A). Mean percentage of pre-B and pro-B cells was calculated and graphed (B). Error bars indicate SD. **P < .01. Of the 5 mice receiving nontransgenic cells, 3 were treated with DOX and 2 without, and there was no appreciable difference in disease latency or phenotype.