Since we showed above that CDK9 is essential for MLL-AF9- and MLL-ENL-driven MYB transcription in reporter assays and that it is recruited to MYB by the MLL-AF9 protein, we wished to investigate the effect of CDK9 inhibitors on MYB transcription, particularly in MLL-fusion driven leukaemia cells. Here, MYB is linked to leukemia.