Conversely, the loss of Pax5 in Pax5Jak2/+Rosa26BirA/+ B‐ALL cells resulted in a similarly high number and extensive overlap of the Pax5‐Jak2 peaks compared with the Pax5 peaks identified in Pax5Bio/Bio pro‐B cells, although the binding density was still higher for full‐length Pax5 compared with Pax5‐Jak2 (Fig 5B and Appendix Fig S5C and D). This evidence concerns the gene JAK2 and acute lymphoblastic leukemia.