Fig. 3. Immunocytochemical analyses of (A) H3(K9) dimethylation, (B) H3(K9) acetylation and (C) H3(K4) dimethylation patterns in A549 cells treated with TSA or NaBt. (Top row) Overlays of TO-PRO-3 counterstained images (middle row) with immunocytochemical staining (bottom row). Nucleolar regions are indicated by yellow arrows, the nuclear periphery by white arrows, and interchromatin compartments by blue arrows. The red arrow in C indicates the non-uniform nature of the peripheral shell. (D) Quantitative analysis of the distribution of H3(K9) dimethylation, H3(K9) acetylation and H3(K4) dimethylation across interphase nuclei. The fluorescence intensity was evaluated across the region indicated by the rectangle in each panel using Andor iQ software. The images represent the histone modification patterns induced by HDACi in the majority of the cell population. Bars, 1.5 µm.