The sensitivity to the compound as single agent did not correlate with leukemia cell type (B-ALL vs T-ALL), with the mutational status of the tumor-suppressor p53 (BV-173, SUPB-15, NALM-6 and NALM-19 cells are p53 wild-type whereas REH, MOLT-4, RPMI-8402 and CEM cells are p53 mutated) (Figure 1A; Table 1) or with the basal expression of Chk1 or Chk2 proteins (data not showed). Here, CHEK1 is linked to leukemia.