SEMA3B and neoplasm: Unlike similar cleavage products derived from sema3A or sema3B which lack bioactivity or display strongly reduced activity, p61-Sema3E retains the activity of full-length sema3E, but unlike full length sema3E, also able induces the formation of complexes between plexin-D1 and the ErbB2 tyrosine-kinase receptor resulting in the in-trans activation of ErbB2 signal transduction, which in turn promotes tumor metastasis [14].