Reverse transcriptase-polymerase chain reaction (RT-PCR) for E2A-PBX1 fusion transcripts was performed prior the treatment using specific primers previously described [13], confirmed the presence of the TCF3/PBX1 fusion (E2A/PBX1 transcript; 373-base pair band), most often identified in acute lymphoblastic leukemia (ALL; data not shown). The gene discussed is PBX1; the disease is acute lymphoblastic leukemia.