PLXNB1 and neoplasm: Semaphorins are a family of membrane-associated or secreted glycoproteins, initially involved in axonal guidance, and relevant to cancer progression by modulating cell migration of leukocytes, neurons, and endothelial cells.171 In tumor-associated macrophages, semaphorin 4D (Sema4D), induces tumor angiogenesis and vessel maturation by binding to the plexin B1 receptor on endothelial cells, and the effect is blocked by plexin B1 antibodies, and by the c-Met inhibitor (PHA-665752).