Fig. 8. Suppression of Beclin expression does not interfere with endocytosis of the fluid phase marker horseradish peroxidase (HRP). Control () and Beclin KD () cells were seeded at the same density, grown for two days and then incubated for the indicated periods of time with 2 mg/ml HRP in DMEM + 1% BSA. Washed cells were lysed and HRP activity was determined as described in the Materials and Methods. Each point represents the mean ± s.e. from three determinations on parallel cultures. Similar results were obtained when the experiment was repeated with different batches of control and Beclin KD cells derived from separate retroviral infections and puromycin selections.