Fig. 3. Geldanamycin affects ErbB2 internalization rather than recycling. (A) Confocal images of control and geldanamycin-treated SK-BR-3 cells where recycling was inhibited with monensin. The cells were treated with 3 µM geldanamycin (GA) and/or 10 µM monensin (Mon) and incubated for 2 hours at 37°C. (B) Histograms of the r2i values from SK-BR-3 cells. The upper graph shows cells that were treated with 3 µM geldanamycin for 2 hours or untreated. The lower graph shows cells that were treated for 2 hours with 3 µM geldanamycin and/or 10 µM monensin alone. Cells were stained as described in Fig. 1A, and the statistical analysis done using a two-sided Mann-Whitney U-test. Note that intracellular ErbB2 is seen only after geldanamycin treatment. Bar, 20 µm.