To validate the early role of Pbx1 as a direct downstream target of MNX1-induced epigenetic modification, and the secondary roles of Pbx4 and Pbxip1 that emerge only during leukemic progression, we treated preleukemic MNX1-transduced FL cells with the pan-methyltransferase inhibitor Sinefungin, previously shown to block MNX1-mediated histone methylation and leukemia induction5. Here, PBX4 is linked to leukemia.