FIG. 2.

Analysis of the acetylation status of histones H3 and H4 after treatment of P1798 cells with inhibitors of HDAC (depsipeptide [Depsi] and TSA) alone or in combination with 5-AzaC. Cells were treated with the inhibitors under the same conditions as described in the legend to Fig. 1. Nuclei were isolated, and histones were extracted with 0.4 N H₂SO₄, precipitated with TCA, and dissolved in water. (A) Equal amounts of protein (100 μg) were run on acid-urea gels to separate the different acetylated forms of histones. The gel was stained with Coomassie blue to visualize the proteins. (B) The protein from an identical gel was transferred to a nitrocellulose membrane and subjected to immunoblot analysis with antibodies against acetylated H4 histone (Ac-H4). For controls, some cells were not treated with an HDAC inhibitor (−). The numbers 0 to 4 on the ordinates indicate un-, mono-, di-, tri-, and tetra-acetylated histones.