Platelet surface β1–4 galactose exposure using FITC-conjugated R. communis agglutinin I (RCA-I, Vector Labs) and FITC-conjugated E. cristagalli lectin (ECL, Vector Labs), and Mpl expression were determined by flow cytometry.20 (link) To determine Mpl internalization platelets were incubated with 50 ng ml−1 TPO for 10 min at 37 °C or not (rest), then all samples were incubated with a rabbit antibody directed against the extracellular domain of Mpl (provided by Dr. Wei Tong, UPenn) or control rabbit IgG, followed by Alexa Fluor 488-labeled goat anti-rabbit IgG antibody, and analyzed by flow cytometry.