In one of our previous studies combining microarray data from 535 Caucasian pediatric ALL samples, we identified 62 marker probe sets (mapped to 61 ENTREZ genes), which could classify ALL into 6 known subtypes, including t(12;21) (ETV6-RUNX1), t(9;22) (BCR-ABL1), t(1;19) (TCF3-PBX1), t(4;11) MLL rearrangement, T-ALL, hyperdiploid with more than 50 chromosomes (hyperdiploid >50), and 1 unknown (Others) subtype. This evidence concerns the gene PBX1 and acute lymphoblastic leukemia.