Trapping of carboxylated beads. Carboxylated red fluorescent polystyrene beads (red) were monitored by time-lapse epifluorescence microscopy on a customized iMIC setup (FEI) at the apical surface of nonconfluent MDCK cells stably transfected with Lifeact-GFP (green). Frames were taken every 2 s for 200 s. Video to Fig. 8 B.
