PRPS1 and acute lymphoblastic leukemia: Moreover, the significant association of the NT5C2 and PRPS1 mutations with the 6MP resistance was observed in all of the 106 cell lines (Figure 5D), in 63 cell lines established at relapse (Figure S12) and in 88 cell lines (67 BCP‐ALL cell lines and 21 T‐ALL cell lines) with the wild‐type NUDT15 genotype (Figure 5D).