– Semaphorin-4D is also known as A8,BB18, GR3, CD100. Semaphorin-4D belongs to the semaphorin family containing 1 Ig-like C2-type domain, 1 PSI domain and 1 Sema domain. It is the cell surface receptor for PLXN1B and PLXNB2 that plays an important role in cell-cell signaling. It promotes the migration of cerebellar granule cells and of endothelial cells, regulates dendrite and axon branching and morphogenesis. Semaphorin-4D Plays a role in the immune system; Promotes signaling via SRC and PTK2B/PYK2, which then mediates activation of phosphatidylinositol 3-kinase and of the AKT1 signaling cascade.