Cno functionally interacts with the Robo downstream effectors Abl, Ena, Sos, and Rac GTPases. A–F, Ventral views of stage 16 embryos stained with anti-Fas2. Transheterozygote mutant embryos for cno2 and Sos97 (A), MtlΔ (B), Rac1J11, Rac2Δ, MtlΔ (C, D), Abl4 (E), and enaGC5 (F) showed specific guidance defects compared with WT embryos (see Fig. 1G). G, Quantitations of guidance defects in the genotypes specified. Scale bar, 10 μm.