Effects on histone acetylation. (A) Electrophoretic separation of histones isolated from GM979 cells treated with 15 μM compound SW68 (lanes marked 1), 15 μM compound SW70 (lanes marked 2), or control GM979 cells cultured in the absence of HDAC inhibitors (lanes marked C). Histone preparations (5 μL, 8 μL, or 10 μL) were loaded to the gels. (B) Ratio of acetylated to nonacetylated histone H4. Notice that SW68 and SW70 increase the ratio by at least 3-fold. Error bars indicate SD.