Impaired calcium influx in Orai1^R93W platelets. (A) Schematic diagram showing the targeting strategy for Orai1^R93W knockin mice. A detailed description of the targeting strategy is given in Document S1. (B) Calcium flux in Orai1^R93W platelets. Fluo-3–labeled WT (gray line) or Orai1^R93W platelets (black line) were stimulated with the indicated agonists in the presence of 0.5 mM CaCl₂. In the thapsigargin (TG) experiment, cells were first treated with TG in the absence of extracellular Ca²⁺ followed by addition of 0.5 mM CaCl₂ (arrows). Mean fluorescence intensity (MFI) was recorded over time on a FACSCalibur. Results are representative of 5 independent experiments. Cvx, convulxin; PAR4p, PAR4 receptor activating peptide.