Results show that a majority of poised and intermediate enhancers in day 1 following IKAROS re-expression are associated with both IKAROS/HDAC1 occupancy, while HDAC1 occupancy has a dominant role in formation of poised and intermediate enhancers during the second day following IKAROS re-expression into IKAROS-null T-ALL (Fig. 5C). The gene discussed is HDAC1; the disease is acute lymphoblastic leukemia.