Western blot showing expression and accumulation of p53 protein in ALL cell lines. Protein was harvested from irradiated cells (18 hours post-IR) and from untreated control cells (C). Blots were analyzed with an anti-p53 antibody (Ab2; Oncogene Science) that recognizes both wt and mutant p53. p53 phenotypes: mutant-p53⁺, EU-2; wt-p53⁺, EU-3, Sup-B15, UoC-B3, UoC-B4, and EU-1; and p53-null, EU-8.