DDX3X and fatty liver disease: Given that DDX3 interacts with HCV core and NS5A16, 17, 18, 34 and is down-regulated by HCV infection (Fig. 1a), HCV infection may interfere with the DDX3-augmented transactivation activity of HNF4 on MTP promoter leading to reduced MTP expression by which, at least in part, HCV infection induces liver steatosis.