BackgroundInformation | Proliferatingcellnuclearantigen(PCNA)isa36kDamoleculethatishighlyconservedbetweenspecies.PCNAwasfirstidentifiedastheantigenforasubpopulationofautoantibodiesinpatientswithsystemiclupuserythematosus(Miyachi,1978;Takasaki,1984;Ogata,1987).IthassincebeendeterminedthatPCNAservesasaco-factorforDNApolymerasedeltainS-phaseaswellasduringDNAsynthesisassociatedwithmechanismsinvolvedinDNAdamagerepair(Tan,1987;Bravo,1987).ThetemporalspecificityofPCNAexpressionmakesitanidealMarkerforcellproliferation.PCNAbeginstoaccumulateduringtheG1phaseofthecellcycle,ismostabundantduringtheSphase,anddeclinesduringtheG2/Mphase(Kurki,1988).Sincethehalf-lifeofPCNAexceeds20hours,itmaybepossIBLetodetecttheproteininnon-cyclingcells. |