Abstract
Neurons establish specific connections by extending projections to contact their targets. Projections, such as axons, navigate to the target by sensing guidance cues in their environment and responding with directed movement and shape change. The recent identification of the molecular identities of many guidance cues and guidance receptors has demonstrated that axons are guided to their targets by combinations of cues that attract and repel them. The current challenge is to elucidate how these guidance cue/receptor interactions control navigation. This review focuses on recent progress in identifying the signaling pathways downstream of these receptors and in determining why an axon is attracted or repelled by a particular guidance cue.