Arp2/3 complex inhibition reduces F-actin barbed end density along the leading edge. (A) Growth cones were dual-labeled with TRITC-phalloidin to show total F-actin (left) and Alexa 488 G-actin, which incorporates at barbed ends (right). Growth cones were treated with vehicle (DMSO, 20 min, top), CK666 (50 µM, 3 or 20 min), CK689 (100 µM, 20 min), or CK666 (50 µM, 20 min) followed by washout for 30 min. Yellow dotted line demarcates the leading edge. Arrow, intrapodia; arrowheads, barbed ends on filopodia. (B) Line scan analysis of barbed-end localization in growth cones under each condition in A. Scattered dots represent dataset from individual growth cones. Solid lines represent the population average. n, growth cones measured. (C) Average barbed-end intensities in the distal half of the P-domain in each condition. *, P < 0.01 with two-tailed unpaired t test versus control; NS, not significant.