RUNX1 and acute myeloid leukemia: Core-binding factor (CBF) acute myeloid leukemia (AML), comprising up to 12–15% of all AML cases [1–5], is characterized by the presence of either t(8;21)(q22;q22) or inv(16)(p13q22)/t(16;16), which leads to the formation of RUNX1/RUNX1T1 (AML1/ETO) [6] and CBFB/MYH11 [7] fusion genes respectively.