Figure 9.

BFA-stimulated tubule formation from endosomes is inhibited by ITD in a dose-dependent manner. HeLa cells were washed with MEM (without serum) and preincubated with various concentrations of ITD in MEM for 10 min, BFA (5 μg/μl) was added (in the continuous presence or absence of ITD as appropriate), and cells were further incubated for 15 min at 37°C. Cells were fixed and stained by immunofluorescence to visualize Tf receptors. (A-C) Immunofluorescence micrographs: (A) control, untreated cells; (B) cells treated with BFA showing extensive membrane tubules; (C) cells pretreated with 50 μM ITD before BFA treatment. (D) Quantitation of immunofluorescence experiments. Results show the mean ± 1 SD (n = 3 for all data points).