Fig. 3. Localization of p80 in multivesicular endosomes. Dictyostelium cells were untreated (A) or treated with U18 for 15 minutes (B) or 2 hours (C). Cells were then collected and processed for cryosectioning and immunostaining to detect the p80 endosomal marker. Bar, 0.5 µm. (D) Cells labeled with [³⁵S]methionine were chased for 0, 1, 2 or 4 hours in the presence of absence of U18. They were then lysed and the labeled p80 was analyzed by immunoprecipitation and SDS-polyacrylamide gel electrophoresis.