Fig. 5. Involvement of the actin cytoskeleton, but not microtubules, in heparanase endocytosis. Human foreskin fibroblasts were incubated with 10 µg/ml 65 kDa heparanase for 120 minutes in the absence (control) or presence of cytochalasin D or nocodazole. After fixation and permeabilization, immunofluorescent staining was performed with anti-heparanase mAb 130, followed by Cy3-conjugated goat anti-mouse antibody. Heparanase-containing granules were detected and quantified as described in the Materials and Methods. There were no granules containing heparanase in the cytochalasin D treated cells, whereas nocodazole had no apparent effect on heparanase endocytosis.