IRF4 and acute lymphoblastic leukemia: Aberrant methylation results in silencing of several critical TFs involved in myeloid lineage specification, including CEBPA, KLF4 or IRF4. Interestingly, IRF4 and a few genes like MAFB (another inducer of monocytic maturation) or KLF4 are completely repressed in CIMP, whereas they remain active in some T-ALL cases.