Regulates the formation or stabilization of cell-cell contacts at several stages of epithelial morphogenesis (PubMed:10648234, PubMed:12403719, PubMed:17761667). In early embryonic development, required for proper ventral closure of the epidermis (PubMed:12403719). During male tail morphogenesis, regulates precursor cell sorting and allows the formation of distinct sensory rays (PubMed:12679110). Seems to control cell-cell contact formation through 2 parallel pathways, one involving efn-4 and one involving plx-2 and unc-129 (PubMed:15030761). Involved in follower axon guidance (PubMed:25358863, PubMed:28846083). In particular, it is required for the guidance of axons from neurons, including SubL neurons and AIY interneurons, into the nerve ring (PubMed:28846083). Probably by binding receptor plx-2, regulates fln-1-mediated remodeling of the actin cytoskeleton and thus axon guidance and/or fasciculation of DD/VD neurons (PubMed:25358863). Required for the guidance of axons from neurons, including AIY interneurons, into the nerve ring. Interacts with plx-2. Ubiquitously expressed. Worms have defects both in early embryonic morphogenesis and in postembryonic male tail morphogenesis. Belongs to the semaphorin family.