For example, mammary tumor growth and metastasis induced by the polyomavirus middle T (PyMT) oncogene are reduced in Mgat5−/− mice (knockout for the gene encoding MGAT5) [47], whereas Mgat3−/− mice (knockout for the gene encoding MGAT3) exhibit an accelerated appearance of mammary tumors induced by PyMT [48]. The gene discussed is MGAT5; the disease is breast cancer.