Surface-bound HGF detected by flow cytometry. (A) Histogram of JJN-3 cells stained with the mouse monoclonal anti-HGF antibody 2B5 and fluorescein isothiocyanate (FITC) anti-mouse IgG before and after washing cells with heparin. The background staining obtained with the irrelevant antibody 18D11 and FITC anti-mouse IgG is also indicated. (B) Histogram of OH-2 cells before and after incubating cells with 1 μg/mL HGF followed by extensive cell washing before labeling with 2B5.