Halogenated nucleotides such as the pyrimidine analog bromodeoxyuridine (BrdU) can be used to label nascent DNA in viable cells. During the process of DNA replication, BrdU can replace thymidine and incorporate into the synthesized DNA of actively dividing cells. methods for labelling nascent DNA
http://cellassay.creative-bioarray.com/services/brdu-cell-proliferation-assay.htm
