Fig. 5. (A) The dorsal hole of stage 15 GAL4^332.3;UAS-Drac1N17 embryo late in dorsal closure showing strong leading edge phosphotyrosine staining. The amnioserosa cells near the top of the figure have changed shape properly (arrowhead), but the cells toward the bottom of the figure have not (arrow). The leading edge has progressed further toward the dorsal midline on the side of the embryo at the top of the figure. The amnioserosa cells and dorsal hole of this embryo can be compared with those of the wild-type embryo late in dorsal closure shown in Fig. 1G. (B) Dorsal surface of stage 16 GAL4^332.3;UAS-Drac1N17 embryo showing successful but distorted dorsal closure.