The RSK inhibitor LJH685 enhanced activation of not only ERK, but also its upstream activator MEK, while the ERK inhibitor SCH772984 drastically enhanced activation of MEK, but not ERK in MV4-11, as well as primary FLT3-ITD-positive AML cells (Figure 4A,B). This evidence concerns the gene RPS6KA3 and acute myeloid leukemia.