The IGFBP3 mRNA was present in all subtypes of B-ALL, with the highest expression in the KMT2A-rearranged and ETV6-RUNX1 subtypes and the lowest in the TCF3-PBX1 and BCR-ABL1 subtypes (Figure 3B). Here, PBX1 is linked to precursor B-cell acute lymphoblastic leukemia.