Neuronal guidance proteins include, but are not limited to, semaphorins and their receptors, plexins; netrins and their receptors, deleted in colorectal cancer and UNC5; Eph receptors and their ligands, ephrins; Slit and its receptor, Robo; repulsive guidance molecules and their receptor, neogenin; Wnt proteins and their receptor, Frizzled; and protocadherins. Here, NEO1 is linked to colorectal cancer.