The results of in vivo animal studies prompted us to further investigate the roles of hormones such as insulin and dexamethasone in the regulation of Enpp1 expression as these hormones are major players in the regulation of expressions of hepatic genes for the glucose and lipid metabolism The Enpp1 mRNA level was clearly up-regulated by dexamethasone and inhibited by insulin treatments in primary rat hepatocytes and HepG2 human hepatoma cells. This evidence concerns the gene ENPP1 and hepatocellular carcinoma.