Semaphorins are a large family of proteins with over 30 members, which are further divided in subgroups¹. They are involved in signaling and are implicated in diverse developmental processes such as axon guidance during nervous system development and regulation of cell migration². They are highly expressed in mammary gland, kidney, fetal brain, and lung and expressed at lower levels in heart and liver tissues².

All semaphorin members have a secretion signal, a 500-amino acid sema domain, and 16 conserved cysteine residues³. The semaphorin 3 family have a basic domain at the C-terminus. They bind neuropilins which subsequently activate signaling through associated plexins. Semaphorin-3B and semaphorin-3F function additionally as potent inhibitors of tumor development in small cell lung carcinoma. Recent evidence indicates that these semaphorins modulate the adhesive and migratory properties of responsive malignant cells. Semaphorin-3F was also functions as an inhibitor of angiogenesis, contributing significantly to its anti-tumorigenic properties¹.