BCR and acute lymphoblastic leukemia: To test whether the expression of IL7R and CXCR4 is also correlated in primary ALL, we analyzed a cohort of 68 Ph+ BCP-ALL patients (patients’ characteristics are given in Supplementary Table 2) and found significant correlation of IL7R and CXCR4 gene expression (Spearman r = 0.6264; p < 0.0001; Fig. 2a), suggesting that our sequence analysis of BCR-ABL1-transformed pre-B cells is in accordance with in vivo condition.