FIG. 1.

Optimization of drug concentrations to inhibit endocytosis. CRFK cells were treated with drugs at various concentrations: (a) chlorpromazine, (b) nystatin, (c) bafilomycin A1, (d) chloroquine, (e) cytochalasin D (cytD), (f) nocodazole (noco), or (g) untreated. (a and b) Cells were then incubated on ice for 30 min with transferrin (black bars) or cholera toxin (grey bars) in the presence or absence of the various drugs. Samples were then transferred to 37°C for a further 30 min. The cells were fixed and examined by fluorescent microscopy. (c and d) Cells were incubated with 2 μM acridine orange for 1 min before washing three times with PBS. Samples were mounted using Citifluor and examined immediately by fluorescent microscopy. (e, f, and g) Cells were fixed and examined by fluorescent microscopy. This experiment was repeated twice and this figure represents one experiment.