Fig. 7. Dizzy behaves like a Rap1-GEF in vivo. Embryos solely expressing dominant-negative rap1^N17 (A,C) compared with embryos simultaneously expressing rap1^N17 and dizzy^EP (B,D) in macrophages. (A) The expression of rap1^N17 severely disrupts the migration of macrophages along the VNC. (B) This effect of rap1^N17 is rescued by the simultaneous expression of dizzy, presumably by substituting for GEFs sequestered by Rap1^N17. (C,D) Similarly, the effect of Rap1^N17 on macrophages migrating along the dorsal edge (C) is rescued by the coexpression of dizzy (D). A,B: sagittal optical sections; C,D: magnifications of similar areas as indicated by the rectangle in Fig. 6C.