This is based on different types of studies ranging from retrospective and prospective studies showing no change in liver cancer in humans treated with PPARα ligands (e.g., fibrate drugs), to preclinical studies showing that Ppara-null and PPARA-humanized mice are refractory to liver carcinogenesis after long-term administration of PPARα agonists [5,9,13,14,15,16,21,22], and lack of increased proliferation of human hepatocytes in chimeric humanized mice [23]. The gene discussed is PPARA; the disease is liver cancer.