Quantification of (A) tumor burden, (B) normalized tumor number, (C) average tumor size, (D) tumor grade, and (E) phospho-ERK (pERK) staining in LA-1; WT p53 mice 6 months following exposure to no irradiation (No IR), 5 daily fractions of 1.2 Gy X-rays, or 5 daily fractions of 0.2 Gy 56Fe. Each symbol represents 1 mouse (A–D) or 1 tumor (E). No-irradiation data repeated from Figures 4 and 5 for additional comparisons. *P < 0.05 by Kruskal-Wallis test followed by Mann-Whitney test.