Dynamics of GFP-FLN localization during motility in polarized cells. Single plane confocal time-lapse images were acquired during chemotaxis of polarized cells expressing GFP-FLN. Selected panels at varying time intervals are shown. In panel A, the cell has paused and begins a new upward protrusion (arrow in A). At this point, the GFP-FLN probe is localized throughout the peripheral cortex, but weakly in the former front (arrow in A'). The GFP probe transiently localizes to this new protrusion (C', D'), but as extension continues and the cell begins to move upward, the signal is lost from the distal part of the protrusion and eventually from the entire leading edge (F-H). (See the movie in Additional file 4).