ASS1 and cancer: Because CAD phosphorylation has been shown to promote carcinogenesis by enhancing pyrimidine de novo synthesis, while ASS1, a key regulator for urea cycle and arginine anabolic metabolism, has been shown to control carcinogenesis in several types of cancers 20, 21, 23-25, we wondered whether p-CAD and ASS1 are dysregulated in human HCC, and if such dysregulation is related to the loss of VIP/VIRP1.