Overexpression of GFP-Smash-PM causes apical constriction of follicular epithelial cells. (A) GFP-Smash PM (green in Merge) was overexpressed in the follicular epithelium of an egg chamber at stage 10A in clones. Dlg (red in Merge) marks cell outlines close to the apex of the cells. (B) Overview of the egg chamber shown in A. (C) Control clones overexpressing CD8-GFP. (D) Overview of the egg chamber shown in C. (E) Clones of GFP-Smash PM overexpressing cells shown from the side. Note the triangular shape of GFP-Smash PM–overexpressing cells. (F) Control clones overexpressing CD8-GFP shown from the side. Note the cylindrical shape of CD8-GFP–overexpressing cells that does not differ from adjacent cells. (G) Clones of GFP-Smash PM–overexpressing cells were stained for DE-Cad (blue in merged image). Bars, 20 µm. In E–G, apical is up. (H) Quantification of apical perimeter in follicular epithelial cells at stage 10A overexpressing GFP-Smash PM or CD8-GFP in small clones. Adjacent cells immediately touch GFP-positive cells, whereas control cells are more than one cell diameter away from GFP-positive cells. (I) Quantification of apical surface area in follicular epithelial cells at stage 10A overexpressing GFP-Smash PM or CD8-GFP in small clones. Definitions of cell categories as in H. ***, P < 0.001 by unpaired one-tailed t test. Error bars show mean ± SEM. n = 10 egg chambers.