Paired measurement of GpIbα, GpIX, and GpV by flow cytometry. Human platelets and HUVECs were analyzed by two-color fluorescence for GpIbα and GpIX or GpIbα and GpV. PE-labeled goat antimouse IgG was used to detect GpIX and GpV (abscissa); FITC-labeled MoAb Ib1 was used to detect GpIbα (ordinate). See Materials and Methods for experimental details.