A FlnA-dependent network spatially integrates actin SFs. (A–D) Immunogold PREM at increasing magnifications of control scr shRNA NIH3T3 cells. (A) Whole-cell image. Scale bar, 10 µm. (B) Zoomed-in image of boxed region in A. Scale bar, 2 µm. Arrowheads point to a putative FA region with bundled actin. (C) Zoomed-in view of SF region shown in B. Scale bar, 0.5 µm. Inset: Zoomed-in image of yellow boxed region showing the trace of actin filaments visualized as a component of a SF which diverged to join the meshwork of loose actin filaments. (D) Zoomed-in image of white boxed region marked in C showing FlnA immunogold particles on intersecting actin filaments (purple circles) or parallel actin filaments (yellow circles). Scale bar, 200 nm. (E) Quantification of the percentage of gold particle labeling FlnA localized on intersecting and parallel actin filaments within the region of a SF (n = 4,234 gold particles from 10 cells).