α_IIbβ₃ downstream signaling events have variable contributions to proplatelet formation on fibrinogen. (A) Bone marrow aspirates from TPO-treated mice were treated with either DMSO, 20 μM dimethyl BAPTA-am, or 10 μM PP2, and allowed to adhere to fibrinogen for 4 hours at 37°C. Results were tabulated as a percentage of the total megakaryocytes that displayed proplatelets. Error bars represent SEM, n = 3. (B) Bone marrow aspirates from non-TPO-treated PLCγ2^-/- mice or littermate wild-type controls were allowed to adhere to fibrinogen for 3 hours at 37°C. Results were tabulated as a percentage of the total megakaryocytes that displayed proplatelets. Error bars represent SEM, n = 4. ^*Significant difference compared with controls.