Uridine 5'-monophosphate - 13 C 9 , 15 N 2 (5'- Uridylic acid- 13 C 9 , 15 N 2 ) dilithium is 13 C and 15 N-labeled Uridine 5'-monophosphate. Uridine 5'-monophosphate (5'- Uridylic acid), a monophosphate form of UTP, can be acquired either from a de novo pathway or degradation products of nucleotides and nucleic acids in vivo and is a major nucleotide analogue in mammalian milk.