NPI-0052 increases histone-H3 expression and its hyperacetylation. (A) NPI-0052 increases histone-H3 levels and hyperacetylation. Jurkat cells were exposed to 10 nM bortezomib, 10 nM NPI-0052, 5 μM MS-275, or a combination for 6 hours. Cell lysates were prepared and subjected to SDS polyacrylamide gel electrophoresis (SDS-PAGE) and immunobloted for acetylated (Ac)–H3, histone-H3 (H3), and actin. (B) NPI-0052 increases histone-H3 protein expression. Lysates from Jurkat cells treated with 10 nM NPI-0052 were collected at the indicated times. Western blot analyzed histone-H3 and actin expression. (C) NPI-0052 does not induce accumulation of ubiquitinated-histone-H3. Immunoprecipitation (IP) of histone H3 or p27 was performed in protein lysates from Jurkat cells that were treated with 5 μM MS-275, 10 nM NPI-0052, 200 nM NPI-0052, or a combination with MS-275 and NPI-0052 for 6 hours. After IP, samples were run on SDS-PAGE and blotted for ubiquitin. Bottom panel, protein lysates from Jurkat cells treated with the indicated compounds for 6 hours were immunoblotted for total ubiquitin protein expression.