Fig. 1. scar^- cells are defective in phagocytosis, fluid phase pinocytosis and macropinocytosis. To determine the rates of phagocytosis, cells were incubated with 1 µm fluorescent latex beads or FITC-dextran for the indicated times and the intracellular fluorescence was calculated using a spectrofluorimeter. The fluorescence value at each time point was normalized to protein load to account for any difference in cell size among the strains. (A) scar^- cells internalized beads at a rate two to three times less than that of control cells, indicating that the mutant was defective in phagocytosis (n=6). (B) scar^- cells internalized FITC-dextran at half the rate of control cells, indicating that the mutant also defective in fluid phase pinocytosis (n=5). (C-F) Cells were incubated with 2 mg ml^-1 FITC-dextran for 10 minutes, washed twice in fresh HL5 growth medium, spotted onto plastic coverslips and examined using phase contrast (C,E) or fluorescence (D,F) microscopy. Control cells (C,D) contained many large macropinosomal vesicles (arrows), whereas the scar^- cells (E,F) contained no large macropinosomes. Bar, 2.5 µm.