Here, we show that knockdown of Myb in leukaemia cells harbouring either wild-type or Cter/Nter–mutant C/EBPα reverses the abnormal myeloid phenotype normally observed in leukaemia, whereas AML cells carrying biallelic Nter/Nter mutations exhibit persistence of the undifferentiated phenotype. The gene discussed is MYB; the disease is acute myeloid leukemia.