Fig. 2. Brefeldin A induces changes in the microtubule cytoskeleton in a vimentin-dependent manner. (a) SW13 cells stably expressing GFP-vimentin were treated with either methanol (Control) or 10 µg/ml BFA for 30 minutes at 37°C. Following treatment, cells were fixed and processed for immunofluorescence and staining with antibodies against -tubulin. Staining was visualized by confocal microscopy. BFA treatment led to the formation of microtubule processes in close apposition to vimentin. (b) SW13 v- and v+ cells were treated with either methanol (Control) or 10 µg/ml BFA for 30 minutes at 37°C and processed for immunofluorescence. Cells were stained with antibodies to -tubulin and with Rhodamine-phalloidin (to visualize F-actin) and observed by confocal microscopy. Changes in microtubule architecture occurred only in the presence of intermediate filaments in SW13 v+ cells. Process formation or retraction of microtubules was not observed in SW13 v- cells. No changes were observed in cortical actin networks. Bars, 10 µm.