Fascin S289A localizes to the distal end of filopodia and rescues filopodia formation. (A) Wild-type mCherry-fascin (purple) and GFP-fascin S289A/D (green) were coexpressed specifically in macrophages of sn²⁸ mutant embryos. Fascin S289A localized to distal ends of filopodia extending beyond the leading edge (arrows) and to nascent filopodial bundles (asterisks). (B) Line scan analysis of both mCherry-fascin (purple) and GFP-fascin S289A (green) within a dynamic filopodia. (C) LifeAct-GFP was expressed in macrophages in wild-type (wt) and sn²⁸ mutant embryos. (D) LifeAct-GFP and mCherry-fascin or mCherry-fascin S289A were specifically expressed in macrophages in sn²⁸ mutant embryos. (E) High magnification of filopodia in D and line scan analysis show an enrichment of fascin at the distal end of the filopodia (arrows). Note that fascin S289A enrichment was enhanced. Bars, 5 µm. See also Videos 2, 3, 4, and 5.