Deletion of Coro1B/1C impact F-actin dynamics at the lamellipodia. (A) Immunofluorescent staining of F-actin in parental and null cells; scale bar, 10 μm. Lower panels are 2× magnifications of boxed regions above; scale bar, 5 μm. (B) Beeswarm superplot depicting the width of actin at the edge of parental and null cells. Widths are calculated from maximum pixel intensities within 5 μm (lines) of the edge. (C) Representative images of Arpc2 localization in parental and null cells. Scale bar, 30 μm. Top right insets are magnifications of yellow boxed region. Scale bar, 5 μm. (D) Percentage of cell edge positive for Arpc2 signal (length of Arpc2-positive lamellipodia/cell perimeter × 100) for parental (n = 47) and null (n = 54) cells. (E) Fluorescence intensity of Arpc2 within 5 μm of the leading edge of parental (n = 45) and null (n = 34) cells. (F) Representative live-cell confocal micrographs of mScarlet-β-actin and Coro1B-GFP in parental and null cells (left). Scale bar, 5 μm. Corresponding kymographs on the right show mScarlet-β-actin returning to the bleached region indicated with a yellow dashed line in the panels on the left. Images were acquired roughly every 1 s and bleached at t = 3 s and t = 33 s as indicated by red arrowheads. (G) Quantification of polymerization rates in microns per minute of parental (n = 75) and null (n = 71) cells. For all beeswarm superplot graphs, Student’s t tests were performed and error bars denote SEM. *P value <0.041, **P value = 0.0018.