Effect of PI3Kγ- or PLCβ2/β3-null mutations on in vivo thrombosis. Carotid injury was induced by application of FeCl₃-soaked filter paper for 2 minutes, and vessel occlusion was monitored by a Doppler ultrasound. The Doppler tracings show flow (milliliters per minute) on the y axis and time on the x axis. Control mice typically developed stable occlusions within their injured arteries. In contrast, PLCβ2/β3 and PI3Kγ knock-out mice both failed to form stable arterial occlusions in response to chemical injury.