Effect of cytochalasin D on retrograde movement of EGFP-shootin1 speckles in XTC fibroblasts and axonal growth cones. (A) Time-lapse speckle images of mCherry–β-actin (red) and EGFP-shootin1 (green) coexpressed in XTC fibroblasts treated with 1 μM cytochalasin D at 0 min. See Video 4 . (B) Time-lapse speckle images of EGFP-shootin1 in an axonal growth cone treated with 1 μM cytochalasin D at 0 min. See Video 5. Dotted lines indicate the leading edge and boundary of speckles. Bars, 5 μm.