Subsequent studies show that Sema4D participates in axon guidance [2], [3], [4], [5], angiogenesis [6], [7], [8] and tumor progression [6], [9], [10], and that these events are mediated by a high affinity receptor, plexin B1, and possibly plexin B2 [11]. Here, PLXNB1 is linked to neoplasm.