ABL1 and leukemia: In addition, searching in a mixed leukemia gene expression study19 using the R2 database (http://r2.amc.nl) showed that IL7R and CXCR4 are expressed at reduced levels in BCR-ABL+ ALL (t9; 22) in comparison with other BCP-ALL entities (Supplementary Fig. 3a and Supplementary Table 3). Similar results were also observed in RNA-seq dataset of 1223 BCP-ALL patients20 (Supplementary Fig. 3b and Supplementary Table 3).