Arginase-1 is encoded by ATG1 gene, it is a key urea cycle metalloenzyme. Arginase-1 has a high specific expression in normal human liver, which is a sensitive and specific index of benign and malignant hepatocytes. In normal liver, there is no response in bile duct epithelial cells, sinusoidal endothelial cells, Kupffer cells or vascular endothelial cells.