Platelet formation is regulated by PLCγ2 but not FcRγ-chain. Whole blood platelet counts from (A) WT (solid line) or FcRγ KO (dashed line) mice and (B) WT (solid line) or PLCγ2 KO (dashed line) were obtained before immune-induced thrombocytopenia (time point 0, n = 4), followed by an intraperitoneal injection of anti-mouse GPIbα antibody (2 μg/g of mouse weight). Platelet counts were then measured at indicated times (n = 4 for each time points). Error bars represent SEM. *P < .05; **P < .01; ***P < .005.