Organization of the cytoskeleton in I-BAR-induced filopodia.

<p>(A) Correlative platinum replica EM of a GFP-I-BAR-expressing cell in living state (left inset) and after stringent detergent extraction in the absence of PEG (right inset). Actin cytoskeleton is present in most I-BAR-positive filopodia except for those marked by the black outline projected from the live fluorescence image. (B) Zoomed boxed region from A shows aberrant actin filament organization in the I-BAR-induced filopodium. (C,D) Replica EM of cells stably expressing GFP-I-BAR shows variable number of actin filaments inside I-BAR-induced filopodia and frequent association of filopodia with reticular material. Boxes 1–3 are enlarged in adjacent panels.