Inhibition of calpain activity rescues Bcl-xL degradation in platelets. (A-B) Platelets were stimulated with increasing concentrations of A23187 in the presence or absence of MG132 (10μM). After 1 hour, Bcl-xL and actin protein were assessed by Western blot analysis (A) or intracellular Bcl-xL protein was measured by ELISA (B). The bars in panel B represent the mean ± SEM of 4 independent experiments, and the asterisk indicates a significant decrease (P < .01) in Bcl-xL protein levels compared with control and MG132-treated platelets. (C) Platelets were pretreated with or without MG132 and then incubated alone (control) or with UTI89 for 2 hours. Bcl-xL and actin protein in this blot and panel A are representative of 3 independent experiments.
