Platelets lacking PIP5KIγ display normal integrin function. (A) Washed murine platelets lacking PIP5KIγ that were analyzed after agonist stimulation in a Lumi-dual aggregometer. Platelets lacking PIP5KIγ have normal aggregation in response to collagen, PMA, thrombin, and AYP, a peptide agonist of PAR4 (the dominant murine thrombin receptor). Results are representative of 3 experiments. (B) Loss of PIP5KIγ does not impair the binding of Jon/A, an antibody that only recognizes the activated form of αIIbβ3. The results are derived from 3 experiments. (C) Following stimulation of washed murine platelets with thrombin, platelets were fixed, permeabilized, and stained with fluorescent phalloidin. Flow cytometry was used to quantitate phalloidin binding in 100 000 cells, and analysis was performed using FlowJo software. Shown is the mean ± standard error of the mean for 3 experiments. (D) PIP5KIγ^−/− MLC-2v Cre⁺ platelets that were layered onto fibrinogen and allowed to adhere for the labeled time periods. Cells were lysed, and immunoblotted with anti-FAK or anti-phosphorylated FAK antibodies.