Expression of FOXO3(A3) suppresses SCF-mediated mast cell survival. BMCMCs were infected with a retrovirus encoding a dominant-active mutant of FOXO3(A3):ER (▪) and were then either left untreated (–) or incubated with 4-OHT (+) in the presence of SCF for 48 or 72 hours, respectively. Cell viability was analyzed by annexin V staining and flow cytometry. As a control, mock-infected cells (□) carrying the puromycin gene only were treated with 4-OHT. The experiment was repeated 3 times, and the data shown correspond to 1 representative experiment in duplicate (mean ± SEM).