Both of these rearrangements generate a fusion between the gene for Core Binding Factor β (CBFB) and the MYH11 gene, which encodes Smooth Muscle Myosin Heavy Chain (SMMHC) (Figure 1) Expression of CBFB-MYH11 is thought to be the initiating event in inv(16) AML [13, 14]. Here, CBFB is linked to acute myeloid leukemia.