CPS1 and hepatocellular carcinoma: An example of this is the regulation of Carbamoyl phosphate synthetase 1 (CPS1) in the cell urea cycle as the rate‐limiting enzyme, and the high expression of CPS1 is tightly associated with kinds of tumours including LUAD, hepatocellular carcinoma (HCC), gastric cancer (GC) and small intestinal adenocarcinoma [43, 44, 45].