P(122-131) binds to RPTPβ/ζ. Merged images of overlapping co-labelling for biotinylated P(122-131), [B(122-131)] (green) and RPTPβ/ζ (red). Incubation of DU145 cells with B(122-131) for 30 sec (A) or for 20 min (B). Incubation of DU145 cells with B(122-131) and pleiotrophin for 20 min (C). Overlapping labelling appears yellow. B(122-131) was visualized using streptavidin-FITC, while RPTPβ/ζ using specific monoclonal antibody and rhodamine conjugated secondary antibody.