Netrins are a family of secreted molecules first identified for promoting the outgrowth of commissural axons. They are also involved in axon guidance and cell migration. Netrin receptors include DCC (deleted in colorectal cancer), which also includes Neogenin, and UNC5 homologs. The DCC receptors act predominantly through means of attraction, although, it interacts with co-receptors to mediate other signaling events including Netrin repulsion and Netrin presentation. The UNC5 family of Netrin receptors has been characterized in nematodes, insects, and vertebrates. These receptors are necessary and sufficient to mediate repulsion from a Netrin source.