H3K79 methylation in MLL-AF6–transformed cells. (A) H3K79me2 profiles of select MLL-AF9 target genes: Hoxa cluster genes (left) Hox co-factor Meis1 (right). (B) Level and distribution of H3K79me2 profiles around the transcription start site (TSS) of MLL core targets (cyan lines) compared with 3 sets of size-matched, randomly chosen, highly expressed genes based on microarray data from MLL-AF6 leukemic bone marrow cells (gray lines). H3K79 methylation profiles of the highly expressed and nonexpressed control genes are depicted with red and blue lines respectively. Each panel represents data from an independently derived, MLL-AF6–driven murine leukemia. (C) Schematic depiction of experimental design. (D) Western blot showing a marked decrease in H3K79me2 methylation 6 days after transduction with the Cre recombinase compared with control vector (Mi-Tomato)-transduced cells.