Fig. 4. Endosomal H⁺-ATPase and actin are mutually exclusive. (A) Actin was present only on vacuoles stained for p80 but not for H⁺-ATPase (post lysosomes, arrows). Conversely, actin was not observed on vacuoles positive for both p80 and H⁺-ATPase (lysosomes, arrowheads). Bar, 5 µm. (B) Percentage of the p80-positive, actin-positive vacuoles containing no H⁺-ATPase. The means + s.e.m. of three independent experiments are indicated. All the p80-positive, actin-positive vacuoles of at least 30 cells were analyzed for each cell type in each experiment.