We further investigated the upstream regulator of Cyp3a4, the Hnf4a, which is a critical nuclear transcriptional factor that is associated with improved liver function: a previous study demonstrated that Hnf4a expression is decreased in hepatic cirrhosis, but the overexpression of Hnf4a resets the transcription factor network in hepatocytes and prevents hepatic failure [38]. The gene discussed is HNF4A; the disease is liver failure.