Semaphorin 3B (SEMA3B)

The semaphorin/collapsin family of molecules plays a critical role in the guidance of growth cones during neuronal development. The secreted protein encoded by this gene family member is important in axonal guidance and has been shown to act as a tumor suppressor by inducing apoptosis. The 2 genes have widespread but distinct patterns of expression in nonneural tissues, and have different patterns of expression in lung cancer. Human semaphorin A(V) has 86% amino acid homology with murine semaphorin A, whereas semaphorin IV is more closely related to murine semaphorin E, with 50% homology.In particular, overlapping homozygous deletions in lung cancers have been identified in region 3p21.3; more than 90% of small cell lung cancers exhibit LOH at this site.