Fig. 9. CA125-C-TERM is transported to the cell surface by the classical ER/Golgi-dependent secretory pathway. HeLa_MCAT-TAM2 cells stably expressing CA125-C-TERM were grown to 70% confluency. Where indicated, brefeldin A was added to the medium at 5 µg/ml. Following incubation for 90 minutes at 37°C, cells were trypsinized to remove cell-surface CA125-C-TERM and spread onto new culture plates at 70% confluency. The culture was then continued for 4 hours at 37°C in the presence or absence of brefeldin A, as indicated. CA125-C-TERM transported to the cell surface within this time period was quantified by FACS using the mAb OC125. (A) FACS histograms. Autofluorescence was determined by analyzing cells that were not treated with antibodies (light blue curve, filled). The red curve represents cells under steady-state conditions. The light green curve represents cells that were not treated with brefeldin A. Cells that were grown for 90 minutes in the presence of brefeldin A, followed by incubation for 4 hours in its absence, are shown in dark green. Cells that were incubated with brefeldin A over the whole course of the experiment are shown in dark blue. (B) Statistical analysis of four independent experiments. The colors of the bars correspond to the conditions detailed above.