Bromodeoxyuridine (BrdU) is a synthetic nucleoside analogous to thymidine. Incorporated into DNA BrdU is commonly used in the detection of proliferating cells in living tissues to study normal and neoplastic cells. This antibody detects BrdU incorporated into DNA during S-phase of a cell cyclein single stranded DNA, coupled to a protein carrier, also free BrdU. The reaction shows a clear, nuclear confined speckled pattern.