Fig. 3. RhoA^N19 expression disrupts actin organization and epidermal cell morphology. Embryos expressing UAS-RhoA^N19 under the control of prdGAL4 (A,B,F-H) or enGAL4 (C-E) stained with rhodamine-phalloidin to reveal F-actin. In each panel, white bars indicate representative stripes of RhoA^N19 expression. (A,B) Two focal planes of the same high magnification lateral field from a stage 12 embryo undergoing germband retraction; RhoA^N19-expressing cells within the prdGAL4 stripe have flattened and spread (indicated by asterisks in A) over each other and wild-type epidermis (indicated by arrows in B). (C) Stage 13 embryo prior to dorsal closure, extensive filopodia emanate from RhoA^N19-expressing leading edge cells (arrow). Leading edge cells expressing RhoA^N19 (D,F) or co-expressing RhoA^N19 and GMA (H) appear to extend across the amnioserosa and continue to put out extensive filopodia (arrows) as dorsal closure proceeds. These filopodia (arrows) are easily seen at higher magnification (E,G,H).