Fig. 1.

Abl functions in the Netrin pathway to promote EW midline axon crossing. (A,B) Stage 15 embryos expressing TauMycGFP in eagle-positive EW neurons. Axons are visualized with anti-GFP. Four segments are shown. Anterior is up. (A) A fra³/fra⁶ hypomorphic mutant embryo. Occasional defects in EW midline axon crossing occur (arrow). (B) A fra³/fra⁶; Abl⁴/+ embryo. EW crossing defects are enhanced (arrows). (C) Quantification of EW midline-crossing defects in fra and Netrin mutants. ^*P<0.05, ^**P<0.01, ^***P<0.001. n.s., not significant. Error bars indicate s.e.m. Number of segments scored is shown in parentheses.