SEMA3B (Semaphorin-3B) is a secreted protein that functions to guide growth cones and axons in neuronal development. It is considered a tumor suppressor, as it can induce apoptosis and has been found to inhibit tumorigenesis in glioblastoma, lung, breast and renal cancers. In the brain, it has highest expression in the cerebral cortex, hippocampus, basal ganglia and cerebellum. In immunohistochemistry, SEMA3B has granular cytoplasmic and secretory positivity in most tissues throughout the body and in plasma. References: Neuron. 1995. 14 (5): 941–8; Neuron. 2005. 48 (1):63-75, DOI: 10.1016/j.neuron.2005.08.033; PLoS One. 2015; 10(5): e0123369, PMID: 25961819; PLoS One. 2012; 7(8): e42912, PMID: 22936999; PNAS. 2004. 101 (31): 11432-11437, DOI: 10.1073/pnas.0403969101;