Puma plays no role in mast-cell survival induced by FcϵRI crosslinking. (A) Expression of Puma was determined by Western blotting of lysates from wt MLMCs and CTLMCs following FcϵRI crosslinking (IgECL) for 10 hours. Probing for Erk served as a loading control. The results shown are representative of at least 3 independent experiments. (B) Survival of wt or Puma^−/− CTLMCs after FcϵRI crosslinking in the absence of cytokines was measured by staining with PI plus annexin V-FITC. The percentage viable wt cells after FcϵRI crosslinking (following cytokine deprivation) were deducted from viable wt cells after cytokine deprivation and compared with the identically derived results for Puma^−/− CTLMCs. ◇ indicates wt, whereas ● indicates Puma^−/− CTLMCs. N = 3-4 and results are presented as mean (± SD).