The Ampd3^T689A mutation causes increased oxidative stress and cell senescence. (A) Proportion of Annexin V–positive mature RBCs (CD71⁻) (n = 4). (B) Amount of reactive oxygen species in mature RBCs (CD71⁻) as measured by mean fluorescence intensity of H₂DCFDA, for WT (n = 7), Ampd3^T689A/+ (n = 7), and Ampd3^T689A (n = 6). Combined results of 2 independent experiments are shown. (C) Amount of calcium in mature RBCs (CD71⁻) as measured by mean fluorescence intensity of FLUO3-am for WT (n = 7), Ampd3^T689A/+ (n = 7), and Ampd3^T689A (n = 6). Combined results of 2 independent experiments are shown. Black bars represent median. *P < .05; ***P < .001. P values calculated using the Student t test.