Fig. 3. Colocalization of EEA1 and endocytosed FGF1 after 15 minutes. HeLa cells were transiently transfected with FGFR1, 2, 3 or 4 and kept at 4°C with Cy3-FGF1 and 50 U/ml heparin for 2 hours. The cells were washed and incubated in the presence of 0.3 mM leupeptin for 15 minutes at 37°C. The cells were fixed, permeabilized and treated with mouse anti-EEA1 primary antibody. The cells were further treated with Cy2-conjugated anti-mouse secondary antibodies and examined by confocal microscopy. Arrows point to colocalization. Bar, 5 µm.