5-Bromouridine is a brominated analog of the nucleoside uridine .1It can be incorporated into RNA and subsequently detected by antibodies against bromodeoxyuridine .25-Bromouridine decreases the viability of HL-60 and MOLT-4 cells (LC50s = 10 and 20 uM, respectively). It induces apoptosis and halts the cell cycle at the S phase in HL-60 cells. It is photoreactive, and UV irradiation has been used to cross-link RNA containing 5-bromouridine to proteins in the study of of RNA-protein interactions.1,35-Bromouridine can also be incorporated into RNA using 5-bromouridine 5'-triphosphate .