A metastasis suppressor is a protein that acts to slow or prevent metastases (secondary tumors) from spreading in the body of an organism with cancer. Metastasis is one of the most lethal cancer processes. This process is responsible for about ninety percent of human cancer deaths.[1][2] Proteins that act to slow or prevent metastases are different from those that act to suppress tumor growth. Genes for about a dozen such proteins are known in humans and other animals.[3]
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