Increased Tpo-mediated signaling in FAK^−/− megakaryocytes. (A) Lyn kinase assay of megakaryocytes derived from WT and Pf4-Cre/FAK-floxed mice in response to Tpo. Data represent autoradiography (top) and scintillation counts (bottom) of samples in triplicate. Data are representative of the mean (± SEM) of 2 independent experiments. (B,C) Western blot analyses of Tpo-mediated phosphorylation of ERK1/2 and AKT in WT and Fak^−/− megakaryocytes. (D) Tpo-stimulated phosphorylation of FAK (Tyr925) in UT7/Tpo cells. The blotting results are representative of 3 independent experiments.