Characterization of the selected scFv-Fcs. (A) Immunoprecipitation of CD9 molecule by the scFv-Fcs. Cell lysate of HEK293-CD9 was immunoprecipiated by using each antibody indicated on the top of the lane. The immunoprecipitates were resolved by 14% SDS-PAGE and analyzed by immunoblotting with MM2/57. (B) Flow cytometric analysis of binding of the scFv-Fcs to endogenous CD9 on human cancer cells. MKN-28 and HepG2 cells were stained with the indicated antibody and the corresponding FITC-conjugated secondary antibody as described in Figure 3. The open histograms in the left represent the data acquired by the FITC-conjugated secondary antibody only. (C) Immunolocalization of endogenous CD9 on cancer cells by the scFv-Fcs. MKN-28 and HepG2 cells grown on coverslips were stained with the indicated antibody and the corresponding FITC-conjugated secondary antibody. The cellular nucleus was dyed blue fluorescence with DAPI staining. The stained cells were observed using a confocal microscope (400×).