Cc2^−/− platelets are hyperresponsive to stimulation with type I collagen, GPVI, and CLEC-2–selective agonists, CRP and Rhod. (A) Aggregation responses of PRP (platelet count adjusted to 1 × 10⁸/mL) for wild-type (^+/+) and Cc2^−/− mice were determined after stimulation with the following agonists: (a-c) PAR-4 agonist peptide (125-500 µM); (d-f) ADP (2.5-10 µM); (g-i) calcium ionophore (1.25-5 µg/mL); (j-l) type I collagen (1.25-5 µg/mL); (m-o) CRP (0.625-2.5 µg/mL); and (p-r) Rhod (0.12-0.48 µg/mL). Note that Cc2^−/− platelets are hyperresponsive to stimulation by type I collagen, GPVI, and CLEC-2–selective agonists, CRP and Rhod. These data are representative of at least 4 independent experiments performed. (B) Aggregation responses of washed platelets for wild-type and Cc2^−/− mice were determined after stimulation with the following agonists: thrombin (0.25-1 U/mL), PAR-4 agonist peptide (250-500 µM), and CRP (5-10 µg/mL). Note that Cc2^−/− platelets are hyperresponsive to stimulation by GPVI-selective agonist, CRP.