Overlay histogram showing peripheral blood lymphocytes cells stained with ab27401 (red line). The cells were fixed with 4% paraformaldehydel (10 min) and then permeabilized with 0.1% PBS-Tween for 20 min. The cells were then incubated in 1x PBS / 10% normal goat serum / 0.3M glycine to block non-specific protein-protein interactions followed by the antibody (ab27401, 0.5µg/1x106 cells) for 30 min at 22ºC. Isotype control antibody (black line) was mouse IgG1 (0.5µg/1x106 cells ). Acquisition of >5,000 events was performed.