Increased leukemia blast infiltration in DTA_osb mice. (A-C, E-I) Syngeneic 2-month-old C57BL/6 WT or DTA_osb mice were injected with EL4-GFP-Luc cells and leukemia progression was assessed with an in vivo imaging system. (A, B) Luminescence intensity was quantified in the whole body at different time points (A) and shown here in representative images (B). (C) Overall survival of male WT and DTA_osb mice (A-C, n = 9-11 mice per group). (D) Overall survival of female WT and DTA_osb mice (D, n = 4 DTA_osb and n = 10 WT mice per group) measured in a separate experiment performed as described for panels A-C. (E) Hematoxylin and eosin (H&E) staining of bone marrow sections. The area depicted by solid line represents normal bone marrow, with evidence of trilineage hematopoiesis, whereas areas delineated by dotted lines indicate blast infiltrates. Right panels show inset magnifications of indicated areas. Black arrows indicate isolated blasts. (F) Wright staining of blood smears. Blasts with fine chromatin and prominent nucleoli are seen in DTA_osb mice. Blue arrow indicates normal neutrophil, whereas black arrow indicates a blast. (G) H&E staining of liver sections. Arrows indicate blast infiltrates. (H) Representative flow cytometry plots and percentage of MLL-AF9 cells in the bone marrow. (I) Representative flow cytometry plots and percentage of marrow MLL-AF9 cells in G2/M phase. (J) Representative flow cytometry plots and percentage of MLL-AF9 cells in the spleen. (K) Spleen weight over total body weight in leukemic mice. (L) Immunofluorescence staining of spleen sections showing DsRed-MLL-AF9 cells, CD45-expressing (green) cells, and 4,6-diamidino-2-phenylindole nuclei staining (blue). Left panel (×10); right small panels (×63). (M) Survival probability of male and female WT and DTA_osb mice injected with MLL-AF9 cells (n = 11 DTA_osb and n = 10 WT mice). (D-F, n = 5-6 mice per group; G-L, n = 3 mice in WT group and n = 4 mice in DTA_osb group). *P < .05 vs WT mice.