STK11 and non-small cell lung carcinoma: Carbamoyl phosphate synthase 1 (CPS1) is the first rate-limiting enzyme of the urea cycle, and some LUAD patients show significant overexpression23,24, has been found to maintain pyrimidine and DNA synthesis in KRAS/LKB1 co-mutated non-small cell lung cancer (NSCLC) and imposes a specific metabolic vulnerability25.