p38 MAPK inhibition prevents the shedding of GPIb-α from stored mouse and human platelets. GPIb-α surface expression was assessed by flow cytometry. (A) Wild-type mouse PRP was stored 1, 3, 6, 9, 12, and 15 hours at 37°C in the presence of DMSO (vehicle) or the p38 MAPK inhibitor SB203580 (40μM); n = 8. ***P < .001. (Inset) Western blot for GPIb-α in lysates from freshly isolated platelets and platelets stored for 16 hours in the presence or absence of SB203580. The results are representative of 3 independent experiments. (B) PRP was analyzed immediately (fresh) or after storage at 22°C or 37°C in the presence of DMSO (vehicle) or SB203580 (40μM); n = 10. (C) Washed platelets were treated for 60 minutes at 37°C with DMSO (untreated) or 100μM CCCP in the presence of DMSO (vehicle), SB203580 (40μM), or SB202190 (40μM); n = 9. (D) PRP isolated from human blood was analyzed immediately (fresh) or after 72 hours of storage at 37°C in the presence of DMSO (vehicle) or SB203580 (40μM); n = 8. Results are mean ± SEM. n.s. indicates not significant.