Fig. 6. RhoA^N19 expression alters leading edge cell behavior. Lateral (A,B) and dorsal (C-F) views of embryos co-expressing UAS-RhoA^N19 and UAS-GMA via prdGAL4 (A) or enGAL4 (B-F). In stage 12 embryos undergoing germband retraction, stripes of RhoA^N19-expressing cells do not narrow dorsally (A, compare with Fig. 1B; compare Movie 3 with Movie 1 at http://dev.biologists.org/supplemental/), bringing RhoA^N19-expressing stripes into close proximity and allowing leading edge filopodia to initiate cell bridge formation. Regardless of whether cell bridges are formed, extensive leading edge filopodia are clearly observed by the completion of germband retraction (B, compare with Fig. 3C). (C-F) Subsequently, RhoA^N19-expressing leading edge cells spread dorsally and laterally (C) and when filopodia come into contact (arrows), they form ectopic lateral cell-cell adhesions and cell bridges (D-F).