Moreover, using genome-wide analysis of lineage-specific enhancers, Ebf1 and Pax5 motif enrichment in chromatin sites was present only in the original leukaemia and CD19− B phenotype relapse (30–4), but were essentially absent in myeloid or mixed B/myeloid samples (Fig. 4b) which were, instead, characterized by a gain in regions enriched in motifs for Cebp, Batf2 and Irf2, significant myeloid transcription factors, with correlating mRNA expression (Fig. 4c). This evidence concerns the gene IRF2 and leukemia.