Chromatin state at NFI-A gene promoter. Top panels: Schematic representation of the NFI-A regions 1, 2, and 3 and LMO2 gene promoter regions. Numbers are the nucleotides relative to transcriptional start sites (+1) and indicate the location of the PCR primers used in ChIP assay performed at the indicated times in HL60 and HL60R cells in the absence (CTR) or in the presence of 1μM RA (RA) using: (A) anti–RNApol-II; (B) antiacetylated H3 (H3ac), (C) anti-H3K4me3, and (D) anti-H3K27me3 antibodies. Rabbit IgG was used as nonspecific antibody. Samples representing 0.02% of total input chromatin (input) were included in the PCR analysis. (C) Quantitative RT-PCR performed on NFI-A region 1 in ChIP assays using the indicated antibodies in HL60, HL60R treated as described above, and in K562 cells treated or not (CTR) with 0.5μM Ara-C (Ara-C). Data are plotted as the ratio of the values obtained in RA or Ara-C treated versus untreated cell samples. Error bars represents SD of 3 independent evaluations. *P < .05 vs untreated cells. **P < .01 versus untreated cells.