Loss of Stat5 accentuates mitochondrial damage and caspase activation. (A) Wild-type or Stat5-deficient BMMCs were cultured in IL-3 (0.02 ng/mL), SCF (10 ng/mL), or IL-3 (5 ng/mL) + SCF (50 ng/mL) for 48 hours, and assessed for changes in mitochondrial membrane potential by Di(OC₆)₃ staining. Data shown are representative of at least 3 wild-type and Stat5-deficient populations assessed in 3 independent experiments. (B) Cells were cultured as in panel A for 24 hours and assessed for caspase-9 or caspase-3 activation. Numbers on the right of each histogram indicate means of 4 samples from one experiment. Data shown are representative of 2 independent experiments.