A schematic representation of the role of normal core binding factor and RUNX1-RUNX1T1 fusion protein in hematopoiesis and leukemogenesis, respectively. (A) Core binding factor (CBF) and its role in transcription: The CBF comprises 2 subunits (α and β) that are involved in transcription of genes involved in hematopoiesis. (B) The RUNX1-RUNX1T1 rearrangement leads to recruitment of ETO (encoded by RUNX1T1) that recruits transcriptional repressors, including N-Cor/SMRT and HDAC, that inhibit transcription of hematopoietic genes. GM-CSF, granulocyte-macrophage colony-stimulating factor; IL-3, interleukin-3; TCRb, T-cell receptor beta.