Detection of the _IIbβ₃complex at the Cos-7 cell surface using flow cytometry. Surface expression of the _IIbβ₃ complex was analyzed using EDU-3, an MoAb specific for the complex, and an anti-mouse IgG coupled to FITC as described in Materials and Methods. Fluorescence intensity (log) is on the abscissa and forward scatter constitutes the ordinate. The limit of positivity is represented by a vertical bar and was defined as described in Materials and Methods. The percentage of positive cells corresponded to the percentage of cells where fluorescence was above this limit and was determined for 10,000 cells analyzed for each transfection.