As we also wanted eventually to test this effect in the context of virus infection (see below), we used detection of insoluble PCNA, which acts as a robust direct surrogate for BrdU incorporation [35]–[38] as a marker of cellular DNA synthesis because BrdU incorporation cannot be used to assay cellular DNA synthesis in the context of HCMV infection for two reasons. The gene discussed is PCNA; the disease is viral infectious disease.