PI3Kβ is required to prevent high shear-dependent emboli shedding in vivo. Deep laser injuries of mesenteric arterioles were performed in p110β^flox/flox control (WT) (n = 28) or PF4-Cre/p110β^flox/flox (p110β^null) (n = 17) mice. (A) Thrombus formation was monitored through time by fluorescence microscopy (supplemental Videos 3 and 4). Typical profiles are shown to illustrate the stability (WT) or instability (p110β^null) of the thrombus formed. (B) The thrombus surfaces (µm²) were analyzed and were represented as 2 groups: thrombus size <28 000 µm² (small) or >28 000 µm² (large). A histogram represents the percentage (%) of thrombus formed with (dark) or without (white) emboli shedding. Thrombus instability (emboli shedding) is defined as a decrease of the thrombus surface area ≥5000 µm².