Fig. 6. Internalized ErbB2 colocalizes with CtxB, GPI-anchored proteins and dextran in SK-BR-3 cells without GA. (A-D) Cells were subjected to antibody and/or toxin binding on ice for 1 hour, warmed for 2 minutes, acid-stripped and fixed. (A) Fl-anti-ErbB2 and Alexa-Fluor-594-CtxB (0.5 µg/ml) were bound to cells. (B) Fl-anti-PLAP Fab fragments and Rh-anti-ErbB2 antibodies were bound to cells. (C) Fl-anti-ErbB2 was bound to cells, which were warmed with 1 mg/ml FluoroRuby dextran. (D) Fl-anti-ErbB2 and Rh-Tf were bound to cells. (A-D) Deconvolved images from z-stacks are shown. ErbB2, left; CtxB, PLAP, dextran or Tf, middle; merged images, right. Scale bar: 10 µm. (E) Internalization of biotinylated anti-ErbB2 antibodies was measured by CELISA in cells treated with (squares) or without (circles) GA. Values shown are the mean ± s.e.m. of three experiments.