Mast-cell apoptosis following cytokine deprivation is a p53-independent process. Survival of wt or p53^−/− mast cells in the absence of cytokines or following 30 Gy γ-radiation was measured by staining with PI plus annexin V-FITC (A, top) cytokine-deprived MLMCs, where ◇ indicates wt and ◆, p53^−/−. N = 4 and results are presented as mean (± SD). (A, bottom) Expression of Puma was determined by Western blotting of lysates from wt and p53^−/− MLMCs following cytokine deprivation for 10 hours; the results shown are representative of at least 3 independent experiments. (B, top) Cytokine-deprived CTLMCs, where ◇ indicates wt and ◆, p53^−/−. N = 4 and results are presented as mean (± SD). (B, bottom) Expression of Puma was determined by Western blotting of lysates from wt and p53^−/− CTLMCs following cytokine deprivation for 10 hours; the results shown are representative of at least 3 independent experiments. (C, top) γ-irradiated MLMCs, where ◇ indicates wt and ◆, p53^−/−. N = 4 and results are presented as mean (± SD). (C, bottom) Expression of Puma was determined by Western blotting of lysates from wt and p53^−/− MLMCs following γ-radiation after 10 hours; the results shown are representative of at least 3 independent experiments. (D, top) γ-irradiated CTLMCs, where ◇ indicates wt and ◆, p53^−/−. N = 4 and results are presented as mean (± SD). (D, bottom) Expression of Puma was determined by Western blotting of lysates from wt and p53^−/− CTLMCs following γ-radiation after 10 hours; the results shown are representative of at least 3 independent experiments.