Ca²⁺ mobilization, dense granule release, and P2Y12 function are not affected in platelets from JAK2V617F-positive ET patients. Washed platelets from control and JAK2V617F-positive ET patients were stimulated with the indicated concentrations of SFLLRN (A,B,E,H), SFLLRN (± 1μM AR-C 66096; C), ADP (+100 nM PGE1; D), IGF-1 (F), and TPO (G). Ca²⁺ mobilization was recorded in Fura-2 labeled platelets (A). ATP secretion was recorded for 5 minutes using a luminometer (B), FITC-fibrinogen binding was measured after 15 minutes stimulation as described in Figure 1A (C), VASP phosphorylation was analyzed by immunoblotting (D), and Akt phosphorylation was analyzed by immunoblotting of platelet lysates obtained 5 minutes after stimulation (E-G). Unstimulated platelet lysates from control subjects and JAK2V617F-positive ET patients were analyzed for PTEN and SHIP1 expression levels by immunoblotting (H). The bar graphs show the average (± SEM) increase in [Ca²⁺] (A, n = 4), nmol ATP (B, n = 4), percentage reduction in fibrinogen binding (C, n = 3), and Akt phosphorylation in response to ADP (E, n = 3), IGF-1 (F, n = 5), and TPO (G, n = 5) and relative PTEN (n = 14) and SHIP1 (n = 10) expression levels (H).