Analysis of PCNA (Proliferating cell nuclear antigen) in the cell cycle and application to flow cytometry

PCNA also called cyclin, is a nuclear protein and its synthesis is directly correlated to cell proliferation. At least two intracellular populations of PCNA/cyclin exist, one of which is tightly associated with DNA replication sites. This S-phase associated protein can be used as an antigenic marker for cell growth and more specifically for the S-phase. Data from clinical studies indicate that the expression of PCNA/cyclin, evaluated by immunocytochemistry or flow cytometry, can be a useful diagnostic marker for proliferating cells. In the future, the characterization of tumors might include multiparameter analysis of the simultaneous expression of multiple cell proliferation markers at different cell cycle stages.