Uridine 5'-monophosphate - 15 N 2 (5'-?Uridylic acid- 15 N 2 ) dilithium is 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.