PAX5 and precursor B-cell acute lymphoblastic leukemia: Within B lymphopoiesis, both patient-derived sequencing and murine transplantation studies reveal that IKZF1 directly transactivates PAX5 and EBF1 while repressing BCL6, a transcriptional circuit required for the pro-B to pre-B transition and recurrently disrupted in B-cell acute lymphoblastic leukaemia (19, 62, 63).