Expression of two copies of robo3^Scer\UAS.cSa via Scer\GAL4^12.1 shifts thedbd projection from association with the medial longitudinal fascicle to the intermediate longitudinal fascicle. The dorso-ventral position is unaffected. Occasionally, two branches are formed, one on each of the medial and intermediate fascicles. The dbd projections still undergo proper late stage remodelling, even though their location within the neuropile is abnormal.

Expression of robo3^Scer\UAS.cSa in the giant fiber axon, under the regulation of Scer\GAL4^A307, deflects the giant fiber axons to the extreme lateral edge of the connective in just under a fifth of the cases and these axons are deflected even further laterally as they approach the target area. Expression of robo3^Scer\UAS.cSa, under the control of Scer\GAL4^A307 does not affect the latency of the giant fiber, with only subtle defects in following frequency. Ectopic expression of robo3^Scer\UAS.cSa, under the control of Scer\GAL4^{shakB.lethal.4.1}, in the tergotrochanteral motor neurons has no effect on the anatomy of the giant fiber-tergotrochanteral motor neuron synapse. Physiologically, ectopic expression of robo3^Scer\UAS.cSa under the control of Scer\GAL4^{shakB.lethal.4.1}, in the tergotrochanteral motor neurons has only a subtle effect on giant fiber-tergotrochanteral motor neuron connectivity. Expression of robo3^Scer\UAS.cSa under the control of Scer\GAL4^c17 results in anatomical defects in the giant fiber (GF) system; a proportion of GFs are deflected laterally. The physiological response of the GFs appears normal in these flies.

Expression of robo3^Scer\UAS.cSa under the control of Scer\GAL4^GMR.PF has only a minor effect on retinal patterning.

Expression of robo3^Scer\UAS.cSa under the control of Scer\GAL4^elav.PLu results in a weakly comm-like phenotype. Two copies of robo3^Scer\UAS.cSa results in commissureless segments. Some of the Fas2-expressing longitudinal bundles are fused, but at least two distinct fascicles are still seen. Expression of robo3^Scer\UAS.cSa under the control of Scer\GAL4^ap-md544 leads to an alteration in the lateral position of the ap-expressing neurons, to a position just medial to the intermediate Fas2-expressing pathway.