PI3K is a part of the ADP-independent component of GPVI-mediated Rap1 activation.

(A) Human platelets were pretreated with DMSO or BAPTA-am(BAP, 20 μM), PP2 (30 μM), or LY 294002 (LY, 100 μM), 10 minutes prior to a 1-minute stimulation with CVX (250 ng/mL) or ADP (20 μM). (B) Platelets were pretreated with or without 200 μM 2-MeSAMP and the indicated soluble inhibitors prior to 1 minute of CVX treatment. Control lanes are without agonist stimulation. GTP-bound Rap1 was precipitated and detected as described in Figure 1. These results were confirmed in 4 separate experiments. Note that only LY-treated platelets show significantly reduced levels of GTP-Rap1 in the presence of 2-MeSAMP.