Shootin1 and actin filaments in axonal growth cones and XTC fibroblasts. (A) Immunofluorescent localization of shootin1 in a cultured hippocampal neuron. Arrows and arrowheads denote an axonal growth cone and minor process growth cones, respectively. (B) Deconvolved images of an axonal growth cone stained by anti-shootin1 antibody and rhodamine phalloidin. (inset) An enlarged view of the filopodium in the rectangle. Arrowheads indicate shootin1 accumulation in a filopodium. (C) A fluorescent speckle image of EGFP-shootin1 in an axonal growth cone (left) and time series of the indicated area at 5-s intervals (right). See Video 1 . (D) A fluorescent speckle image of EGFP-shootin1 expressed in an XTC fibroblast (left) and a time series of the indicated area at 10-s intervals (right). See Video 2. Yellow arrowheads denote a speckle of EGFP-shootin1 moving retrogradely. (E) A fluorescent speckle image of mCherry-β-actin (red) and EGFP-shootin1 (green) coexpressed in an XTC fibroblast (left). See Video 3. The kymographs (right) of the peripheral region indicated by the rectangle in the left panel show that the speckles of shootin1 and those of actin retrograde flow moved at similar speeds (lines). Bar: (A) 50 μm; (B–E) 5 μm.