Inhibition of Ca2⁺ elevation in Btk^-/-/Tec^-/-in response to CRP. Traces showing Ca²⁺ elevation induced by thrombin (3 U/mL) and CRP (3, 10, and 30 μg/mL) in wild-type and Btk^-/-/Tec^-/- platelets. The Ca²⁺ elevation traces are all from the same experiment and were performed using a Fluo-4-loaded, washed platelet suspension in a Molecular Devices Flexstation with temperature maintained at 37°C. Agonist addition was automated and conducted at 20 seconds after the initiation of monitoring. Platelets were in the presence of lotrafiban (10 μM) to prevent aggregation. The scale is in arbitrary units derived from the intensity of fluorescence emission from the Fluo-4. Traces shown are representative of 3 parallel experiments.