Effect of apoptosis inhibition on MKs and platelet production. MKs were treated with Q-VD-Oph (25 µM) or dimethyl sulfoxide (DMSO; control) from day 8 to day 15 and analyzed on day 15. (A) Representative flow plots showing CD42b expression vs Annexin V (AnnV) binding or TUNEL positivity in MKs treated with DMSO or Q-VD-Oph. (B) Graph quantifying fold changes in the percentages of MK subpopulations with Q-VD-Oph treatment relative to DMSO. Mean ± 1 SEM is shown for 4 independent studies. (C) Quantification of the percentages of MK subpopulations with DMSO or Q-VD-Oph treatment. Mean ± 1 SEM is shown for 4 independent studies. (D) DMSO and Q-VD-Oph treated MKs were pulse-labeled with FV. Left: representative plot showing FV uptake by LG and HG/CD42b⁺ MKs treated with DMSO or Q-VD-Oph. Right: quantification of FV uptake by DMSO and Q-VD-Oph treated MKs. Mean ± 1 SEM is shown for 4 independent studies. (E) Graph quantifying the relative platelet production at specified time points following the infusion of Q-VD-Oph or DMSO-treated MKs into immunodeficient mice. Platelet production is normalized to DMSO control at each time point. Mean ± 1 SEM is shown for 6 independent studies. (F) Graph quantifying the relative in vitro platelet yield from DMSO or Q-VD-Oph treated MKs for 5 independent studies. *P < .05, **P < .01, ***P < .005, ****P < .001 for all statistical analyses. n.s., not significantly different between treatments for all statistical analyses.