MECOM and acute myeloid leukemia: For validation of candidate TFs used in further proteomic studies, we chose RUNX1 and CEBPA, since (i) both TFs are pioneer TFs and key myeloid transcriptional regulators expressed at sufficiently high levels in inv(3)/t(3;3) AML allowing for subsequent protein capture experiments (Fig. S2a, b); (ii) RUNX1 has been implicated in the regulation of EVI1 previously [29]; and (iii) CEBPA mutations are mutually exclusive with inv(3)/t(3;3) in AML [1, 30].