MS-275–induced histone H3 hyperacetylation in BMMCs. Changes in histone acetylation were monitored sequentially in BMMCs by staining with polyclonal antiacetylated histone H3 antibody (top) and counterstaining with 4,6-diamidoino-2-phenylindole (DAPI; bottom). The images were collected with a Zeiss Axioskop fluorescence microscope (Carl Zeiss, Oberkochen, Germany) equipped with a Hamamatsu C4742-95 camera (Hamamatsu Photonics, Hamamatsu City, Japan) and a Zeiss 63×/1.25 NA oil-immersion objective lens, and were processed with Openlab Software version 4.0.4 (Improvision, Lexington, MA). Note increase in histone H3 acetylation in patient 2 treated at DL 1 for first 2 cycles and at DL 2 for last 2 cycles. Increase in histone H3 acetylation was observed at day 8 and persisted through subsequent cycles.