To investigate whether ETV6-RUNX1 and RUNX1 could be recruited to the RAG locus control region in human pre-B lymphocytes, we performed chromatin immunoprecipitation followed by sequencing (ChIP-Seq) with RUNX1 and ETV6 antibodies in different cells: bone marrow mononuclear cells from 3 childhood BCP-ALL patients negative for ETV6-RUNX1, Nalm6 cells, and REH cells that express ETV6-RUNX1 fusion protein (Supplementary Fig. S2). Here, ETV6 is linked to acute lymphoblastic leukemia.