Here we explore the EGR3 regulome of KMT2A::AFF1 proB-ALL in detail through integration of data derived from massive analysis of cDNA ends-sequencing (MACE-Seq) and chromatin immunoprecipitation DNA-sequencing (ChIP-Seq) of an EGR3-overexpression SEM cell model. The gene discussed is AFF1; the disease is acute lymphoblastic leukemia.