Coimmunoprecipitation of D1-D3 VWF with an anti–P-selectin antibody. HEK293 cells were nucleofected with the P-selectin lumenal domain, seen in Figure 1A, and either VWF-GFP (A) or D1-D3-GFP in Figure 1A. Cells were lysed, and P-selectin was immunoprecipitated from the lysate by the monoclonal anti–P-selectin antibody AC1.2. (B) Coimmunoprecipitation of VWF with P-selectin was determined by Western blot using a rabbit polyclonal anti-GFP antibody.