PBX1 and acute lymphoblastic leukemia: We subsequently assessed paired samples from different subtypes of ALL, including T-cell ALL with deletion of chromosome 1 [T-del(1)], t(12;21) (TEL-AML1), t(1;19) (E2A-PBX1) and t(9;22) (BCR-ABL), and we found similar results among the different subtypes (Figure 3A).