Effect of GIRK channel blockers on G_i-mediated Src activation. Washed aspirin-treated human platelets were stimulated with 2MeSADP (100 nM) in the presence of MRS2179 (100 μM) for different time points at 37°C as indicated under stirring conditions (A), in the absence of exogenously added fibrinogen. In panel B, they were stimulated with 2MeSADP (100 nM) in the presence of MRS2179 (100 μM) and SCH23390 (10 μM), U50488H (10 μM), or SKF38393 (10 μM). The reaction was stopped using 3X sample loading buffer (with DTT). The lysates were subjected to Western blotting analysis and probed with phospho-Src (Y416) (A-B) or PKCδ (lane loading control).