Gα₁₃ serves as a critical adapter mediating GPIIBIIIA signaling in migration. (A-B) Quantification of spread cells per FOV, cleared area per platelet (μm²) and % of migrating platelets for human platelets treated or not with 100 μM mP6 before (pre) or after (wash) initiation of migration (fibrinogen/albumin, A) or retraction (fibrin, B). One-way ANOVA with post hoc Dunnett’s testing. (C) Representative micrographs of migrating (upper, albumin/fibrinogen) and retracting (lower panels, crosslinked fibrin) human platelets (pre-)treated or not with 100 μM mP6. Scale bar, 5 μm. (D) Representative cell shapes and PH images of migrating or retracting human platelets treated or not with 100 μM mP6. Scale bar, 5 μm. (E) Quantification of cell size (μm²) and circularity [a.u.] of human platelets spreading on fibrin(ogen) matrices for the indicated treatments. One-way ANOVA with post hoc Dunnett's testing, comparing the respective shape changes with sham-treated platelets on the same substrate. (F) Representative images of 3D clot retraction experiments of human PRP treated or not with mP6. (G) Micrographs from live imaging experiments using platelets from LifeAct-eGFP mice before (0, 12 seconds) and after (96-246 seconds) treatment with 100 μM mP6. Pink arrows mark actin nucleation at the leading edge, while asterisks indicate marked filopodia formation. Scale bar, 5 μm. Right panel: quantification of # of actin waves (per minute) moving along the leading edge. Student t test, 2-tailed, unpaired. Unless indicated with asterisks, post hoc testing revealed nonsignificant results (P ≥ .05). P values corresponding to asterisks: ∗P < .05, ∗∗P < .01, ∗∗∗P < .01, ∗∗∗∗P < .001.