MAP2K1 and myeloid leukemia: Finally, we also found that in NB4 cells, a non-CML/BCR::ABL1-negative myeloid leukemia cell line expressing wild-type ABL1, MEK1/2 blockade induced a nuclear accumulation of ABL1 (Fig. 3C) and that the ABL1 allosteric activator DPH significantly increased the anti-leukemic effects of PD (Fig. 3Ai, ii).