NPM1 and acute myeloid leukemia: These data indicate different possible cooperation pathways for a CEBPAmono-allelic mutation to drive AML, by either cooperating with mutations involving genes from other functional subgroups (CHIP, NPM1, signaling pathway) or with a second mutation in CEBPA. As the first category, this type of clonal hierarchy is mainly found in de novo AML with normal karyotype.