The basal side of the tumor hotspot has structurally robust cellular organizations.

<p>(A, D) TEMs showing the basal side of epithelial cells in the coldspot (A) and hotspot (D) of wild-type wing discs. Right panels of (A, D): cells in left panels were pseudo-colored individually to be distinguished from neighboring cells. Circular cross-sections (50–500 nm in radius) of filopodial protrusions were colored bright red. Scale bars represent 1 μm. (B, E) Transmission electron micrographs show magnified views of the most basal side of epithelial cells in the coldspot (B) and hotspot (E). Right panels of (B, E): line drawings trace the plasma membranes (black), ECM laminae (blue), and microtubules (red). Scale bars represent 500 nm. (C, F) Three-dimensional confocal images show the basal side of single cells randomly visualized by GFP expression (green) in the coldspot (C) and hotspot (F). Arrows indicate filopodial protrusions. Nuclei were labeled with DAPI (magenta). Scale bars represent 10 μm.