C3 is at the confluence of two activation pathways, plays a pivotal role in the activation of the complement system, and is a key molecule in the activation of alternative pathways, participating in immune regulation, for example, by acting as a nonspecific stimulatory signal for B-cell activation, acting as a mitogen for B-cell proliferation, synergizing with antibodies to enhance the effects of glioma and stimulating the release of prostaglandin E (PGE) from monocytes (37, 38). This evidence concerns the gene C3 and central nervous system cancer.