– Semaphorin 3C is one of six Class 3 secreted semaphorins, which are potent chemorepellents, that play a role in axon and/or vascular guidance during development can be up-regulated in the process of tumor progression. Semaphorin 3C consists of a 20 amino acids signal sequence, a N-terminal Sema domain, a cysteine knot, a furine-type cleavage site, an Ig-like domain, and a C-terminal basic domain. Semaphorin 3C expressed highly in the heart, colon, skeletal muscle, small intestine, testis, ovary and prostate, expressed lowly in the other organs, including the brain.