Consistent with unregulated mitotic proteins as cancer drivers, overexpression of Aurora A in mammary epithelial cells of rodents causes mammary tumors [35, 36], overexpression of NDC80 triggers lung and hepatocellular adenomas and sarcomas [37], and overexpression of PTTG1 (securin) induces hyperplasia and microadenomas of the pituitary [38]. This evidence concerns the gene PTTG1 and breast cancer.