Immunolocalization of MRP4 in human platelets. (A-C) Double-label immunofluorescence microscopy of platelets stained with the anti-MRP4 antibody SNG (green fluorescence, Alexa488-conjugated antirabbit secondary antibody) and a monoclonal antibody against P-selectin, as marker for α-granules (red fluorescence, Alexa568-conjugated antimouse secondary antibody). (D-I) Platelets were preincubated with the fluorescent dye mepacrine (green fluorescence), known to be concentrated in dense granules, and stained with an anti-LAMP2 antibody (E, red fluorescence, Alexa568-conjugated antimouse secondary antibody) or MRP4-MLP (G, red fluorescence, Alexa568-conjugated antirabbit secondary antibody). (C,F,I) Superimposed images.