Fig. 1.

The overexpression of Snail is sufficient to induce ectopic EMT. a Snail-expressing clones (marked by GFP) generated in leg imaginal discs. Images of fixed tissues (top: apical view, bottom: sagittal view), showing the successive steps of cell apical constriction and delamination. Snail-expressing cells are outlined in dashed magenta and epithelium is marked by DE-cadherin in white. Scale bar: 5 µm. b General view and close-up of big clones of cells expressing Snail (marked by the α-catenin in magenta or outline in dashed magenta line) in fixed imaginal leg discs (n = 19) showing the loss of DE-cadherin in clones that have delaminate and migrate below the epithelium (see left frame on the general view and top close-up), while clones inserted in the epithelial sheet keep strong DE-cadherin (see right frame in the general view and white arrows in the bottom close-up). DE-cadherin is in white, myosin II in green and nucleus in cyan. Apical and basal side of the epithelium are outlined in red and yellow, respectively. See also Supplementary Fig. 1a–c. Scale bar: 10 µm in the general view and 2 µm in the close-up. c Clones of UAS-life-act::Ruby (left, control) or UAS-life-act::Ruby; UAS-Snail (right) highlighting the migratory properties acquired by Snail-expressing cells. Note that the clones (red cells) are well integrated in the monolayer epithelium (outlined in white) in the control (left, UAS-life-act::Ruby), while they have delaminated and migrated below the epithelial sheet when Snail is overexpressed (right, UAS-life-act::Ruby; UAS-Snail; asterisk) as seen in the general view in (b). Scale bar: 10 µm. Ap apical, B basal, P proximal, D Distal