Each cellular transition is tightly regulated at the transcriptional level by the action of linage-specific transcription factors (TFs), such as PU.1, Ikaros, myocyte enhancer factor C (MEF2C), E2A and PAX5 among others.1, 2, 3, 4, 5, 6, 7, 8, 9 The deregulation of these particular transcriptional programs may result in a block in the differentiation and a hyperproliferative cellular state, thereby contributing to the development of hematological malignancies such as leukemia and lymphoma. The gene discussed is MEF2C; the disease is leukemia.