Selective sensitivity of primary MLL^PTD/WT AML cells to enhanced cell death with 5′-Aza-CdR and depsipeptide treatment. Primary patient samples with either the MLL^PTD/WT or the MLL^WT/WT genotype were incubated with media alone or treated singly or with the sequential combination of 5′-Aza-CdR followed by depsipeptide as described in “Materials and methods.” At the end of the incubation period, viable cell number was determined by trypan blue dye exclusion. The data are presented as percentage of cell death in the combination-treated cells relative to the media control cells. The P value was determined with the Mann-Whitney U test. Horizontal bars represent mean values.