MTOR and hepatocellular carcinoma: In a previous study, the downregulation of UGP2, a key enzyme in glycogen biosynthesis, was revealed to be associated with the occurrence and development of various cancer types and poor survival of HCC, while the downregulation of ASS1, a key enzyme in the conversion of nitrogen from ammonia and aspartate to urea, was confirmed to support cancerous proliferation via the mammalian target of the rapamycin (mTOR) pathway (Rabinovich et al., 2015; Li et al., 2018; Hu et al., 2020).