ABL1 and acute lymphoblastic leukemia: It should be noted that the karyotypes in our cell lines were highly biased in comparison with those in childhood BCP-ALL patients: 14 cell lines were BCR/ABL1-positive, 13 cell lines were TCF3/PBX1-positive, 12 cell lines were MLL (KMT2A)-rearranged, and 3 cell lines were TCF3/HLF-positive.