In order to substantiate this hypothesis, we examined the pattern of expression of several transmembrane receptors known to mediate Netrin-1 responsiveness: Deleted in Colorectal Cancer (DCC), known to mediate chemoattraction to Netrin-1 [27], and homologs of the Caenorhabditis elegans Unc5 receptor called Unc5A–C (also called Unc5H1–3), known to mediate chemorepulsion to Netrin-1 upon heterodimerization with DCC [30,31]. The gene discussed is NRP1; the disease is cancer.