PBX1 and acute lymphoblastic leukemia: TEL-AML1 translocation [t(12;21) (q13;q22)], TCF3–PBX1 translocation [t(1;19)(q23;p13)], KMT2A (MLL) rearrangements (KMT2A-R), BCR–ABL1 [Philadelphia chromosome (Ph) t(9;22)(q34;q11)-positive] are the most recurrent disease-initiating genetic alterations in BCP-ALL.