ASS1 and hepatocellular carcinoma: For example, ASS1, which encodes arginine succinate synthetase, the rate-limiting enzyme in arginine biosynthesis, is silenced by methylation in some cancer types including renal cell carcinoma, hepatocellular carcinoma, malignant melanoma, glioblastoma multiforme (GBM), and platinum-resistant epithelial ovarian cancer.