CBFB and leukemia: AML with the chromosome inversion inv(16)(p13q22), a driver mutation that generates preleukemic progenitor cells that, upon acquisition of additional cooperating mutations, progress to leukemia, expresses the transcription factor fusion CBFβ-SMMHC (core binding factor β-smooth muscle myosin heavy chain), which cooperates with activating mutations in components of cytokine signaling pathways in leukemia transformation.