KRAS and juvenile myelomonocytic leukemia: Of the myeloid malignancies that harbor RAS mutations or exhibit abnormally high levels of RAS activity, juvenile myelomonocyitc leukemia (JMML), an aggressive and rare childhood cancer [3], almost invariably (~90%) presents with driver mutations in KRAS, NRAS or other genes encoding RAS pathway regulatory proteins [4, 1,5].