Inhibition of histone deacetylase 1 and 2 (Hdac1,2) activities does not affect proliferating cell nuclear antigen (PCNA) localization but leads to increased H4K5ac in S-phase cells. A. Serum-starved NIH3T3 cells were released into S-phase in the presence of DMSO or 3 μM 898 for 18 h or 24 h prior to staining of PCNA for immunofluorescence analysis. Punctate pattern of PCNA staining (arrows) indicative of replicating cells was seen in both DMSO and 898-treated cells. B. Serum-starved NIH3T3 cells were released into S-phase in the presence of DMSO or 3 μM 898 (B) or 233 (C) for 24 h and double immunofluorescence was performed using antibodies to stain PCNA and H4K5ac. Punctate pattern of PCNA staining was used to track cells in S-phase.