Golgi-dependent motility in MDA-MB-231 cells. (a) MDA-MB-231 cells were cultured in the presence (10 μg/ml; BFA+) or absence (BFA-) of Brefeldin A for 30 minutes under serum-starved conditions. Cells were allowed to recover for an additional 3 hours and then examined in transwell motility assays, as described in Methods. Cell motility was quantified at 3 hours. (b) In parallel cultures, cells were treated with Brefeldin A as described earlier, and then equal numbers of cells were plated on collagen. The number of cells was counted at 24 hours and expressed as a percentage of cells plated. Data shown are an average of three independent experiments.