Intracellular level of protein modulators of apoptosis and acetylation of histones H3 and H4.

(A) Western blot analysis of the levels of Bcr-abl, Apaf-1, Bcl-x_L, Bcl-2, Bax, Fas receptor (Fas), and Fas ligand (FasL) in HL-60/neo, HL-60/Bcr-Abl, and K562 cells. β-Actin was used as a control for equal protein loading. (B) Western blot analysis of acetylated histones H3 and H4 in response to treatment with As₂O₃ (1 or 2 μmol/l for 7 days). (C) Western blot analysis of histone H3 and H4 after treatment with 2 μmol/L As₂O₃ for 24 hours. Hyperacetylation was detected by the use of antibody against acetylated histone H3 and H4. Histones were acid-extracted from the indicated cell lines after exposure to As₂O₃. The histone deacetylase inhibitor trichostatin A (150 nmol/L, 24 hours) was used as a positive control.