Fig. 3. Inverse correlation between HDAC-1 recruitment and histone H4 acetylation on DHFR promoter. (A) Chromatin was extracted from cells at different phases of the cell cycle, and immunoprecipitated with anti-HDAC-1 or anti-AcH4 as indicated. The results are expressed as fold variation with reference to the resting cells (mean values from three determinations in three independent experiments, with range bars indicating standard deviations). (B) HDAC-1 protein in immunoprecipitates was monitored in parallel experiments by western blotting with an anti-HDAC antibody. (C) Total RNA was extracted from cells at indicated time points and analyzed by northern blotting using a DHFR or a GAPDH probe, as indicated.