Inside a growing thrombus (A), platelet PI3Kβ promotes Akt activation and the subsequent phosphorylation and inhibition of GSK3α/β. These reactions stabilize and consolidate the thrombus, which becomes resistant even to a sudden elevation of the shear rate. (B) In the absence of platelet PI3Kβ, or upon inhibition of PI3Kβ activity, the thrombus grows normally at physiological shear rates, but Akt and GSK3α/β are not phosphorylated. This prevents thrombus stabilization, and the increase of the shear rate causes the detachment of platelet emboli, leaving a layer of collagen-adherent cells. Professional illustration by Patrick Lane, ScEYEnce Studios.