TP53 and acute lymphoblastic leukemia: Sequence analysis of the TP53 gene in UP-ALL13 did not show the presence of any mutation within its coding region (data not shown), and coherently the UP-ALL13 cell line was found to be highly sensitive to the DNA-damaging agent etoposide, in contrast to p53 mutant T-ALL cell lines such as DND41 and CUTLL1 (Figure 5f).