Fig. 3. Src64B mRNA expression overlaps with drl mRNA expression and SRC64B protein is present in axons. (A) Wild-type Drosophila embryo labeled with a Src64B antisense RNA probe shows Src64B expression throughout the ventral nerve cord (arrow) and in the gut. (B) Double RNA in situ staining for endogenous Src64B mRNA (green) and drl mRNA (red) shows that drl and Src64B overlap in the ventral nerve cord in the anterior portion of each segment. (C) Double RNA in situ staining for endogenous Wnt5 mRNA (green) and drl mRNA (red) shows that Wnt5 is predominantly expressed in PC-associated neuronal cell bodies that do not express drl. (D) SRC64B protein is expressed in the wild-type longitudinal and commissural axons. (E) Axons of a homozygous Src64B^PI mutant embryo are not stained by anti-SRC64B. (F) Fluorescent double-antibody labeling of a third instar larval neuropile ectopically expressing SRC64B (red) and GFP (green) in motoneurons (OK6-GAL4>UAS-GFP). The arrow indicates fasciculated SRC64B-expressing motoneuron axons.