Insulator bodies form in response to osmostress. (A and B) S2 cells stained with CP190 and Mod(mdg4) under normal cellular conditions (A) or after treatment with 250 mM NaCl (B). (C and D) Wing discs from third instar larvae stained for CP190 and Mod(mdg4) under normal cellular conditions (C) or after treatment with 250 mM NaCl (D). (E and F) Orthogonal projections along the indicated axes (yellow dashed lines) in an unstressed (E) and stressed (F) S2 cell. The red box outlines the x-y plane image. Note that A–D are maximum projections of 1-µm z slices, whereas E and F are a single z slice (x-y plane only). Bars, 2 µm.