KRAS and acute myeloid leukemia: To confirm our observation in the hematologic malignant cells from patients, we examined the relative abundance of KRAS4A and KRAS4B mRNA in bone marrow samples from patients suffering acute myeloid leukemia (AML) with oncogenic KRAS mutations by reverse transcriptions-quantitative polymerase chain reaction (RT-qPCR) as previously described [23].