In vivo effects of MS-275 on histone acetylation as determined by Western blotting. (A) Serial analysis of histone acetylation in BMMCs and PBMCs of patient 26 treated at DL 4 as determined by Western blotting using antibodies against acetyl-histone H3 and acetyl-histone H4. Histone H2A served as a control protein. (B) Serial PBMCs and BMMCs from 9 patients treated at DL 4 (n = 8) and 5 (n = 1) were analyzed by Western blotting for histone acetylation as described above. Intensity index was calculated as a ratio of intensity of acetylated histone H3 or H4 band to band intensity of nonacetylated H2A as determined by Western blot analysis using antibodies against acetyl-histone H3, acetyl-histone H4, and histone H2A and expressed as fold increase ± SEM over the baseline value.