Fig. 3. LPR1-labeled filopodia are dynamic and exhibit both retractile and protrusive motion. Phase-contrast (lower frame) or EGFP fluorescence (upper frames) images of two HeLa cells expressing EGFP-tagged LPR1 are shown. The panels are individual frames taken from supplemental material Movies 1-4. The numbers on each panel denote the time at which each image was captured. (A) Arrows denote filopodia that steadily diminished in length throughout the period observed. (B) Arrows in each panel indicate either newly formed filopodia or filopodia that have increased in length compared with the previous time frame. Bars, 10 µm.