The HSV-1 regulatory protein ICP27 accumulates in the cytoplasm of infected cells treated with actinomycin D. Cells were infected with HSV-1 strain KOS. Cells shown in a–c and g–i were not treated with inhibitors and were fixed 7 hr after infection. Actinomycin D (10 μg/ml) and cycloheximide (100 μg/ml) were added to the cells shown in d–f and j–l beginning 4.5 hr after infection for a period of 3 hr. Immunofluorescent staining was performed with monoclonal antibodies to the HSV-1 proteins ICP27, ICP4 and ICP8, and to the cellular proteins, hnRNP A1, hnRNP C, and SC35, as indicated.