Loss of Puma allows long-term survival of cytokine-deprived mast cells. Cytokine-induced proliferation of wild-type (wt) and Puma^−/− MLMCs after re-addition of cytokines following 96 hours of cytokine deprivation. (A) Total cell number and viability were determined using trypan blue staining at 24, 168, and 240 hours after re-addition of cytokines, where □ indicates viable wt MLMCs and ■ indicates viable Puma^−/− MLMCs, whereas ◇ indicates total cell number of wt and ●, Puma^−/− MLMCs. (B) Total cell number and viability were determined using staining with PI plus annexin V-FITC and addition of a known number of beads followed by FACS analysis at 24, 168, and 240 hours after re-addition of cytokines, where □ indicates viable wt MLMCs and ■ indicates viable Puma^−/− MLMCs, whereas ◇ indicates total cell number of wt and ●, Puma^−/− MLMCs. N = 4 and results are presented as mean (± SD).