TP53 and breast cancer: Carbamoyl phosphate synthetase 1 (CPS1), a multidomain mitochondrial rate‐limiting enzyme protein, catalyze the first committed step of the urea recycle by converting ammonia into carbamoyl phosphate for ammonia detoxification and disposal.[6] We found that in TP53‐mutant BC, the CPS1 expression level was significantly upregulated (Figure 1b).