5-Bromo-2'-deoxyuridine (BrdU) is a thymidine analog used as a mutagen in genetic research. BrdU is selectively incorporated into cellular DNA during S-phase.5-Bromo-2'-deoxyuridine is used to measure DNA synthesis and to label dividing cells for the study of cell signaling and other processes that induce cell proliferation. 5-Bromo-2'-deoxyuridine (BrdU) is a thymidine analog used as a mutagen in genetic research. BrdU is selectively incorporated into cellular DNA during S-phase.5-Bromo-2'-deoxyuridine is used to measure DNA synthesis and to label dividing cells for the study of cell signaling and other processes that induce cell proliferation.