Reactivation of p15INK4b using DNMT and HDAC inhibitors is associated with an increase in H3K4me3 and maintenance of H3K27me3 in KG-1 and AML blasts. ChIP-quantitative PCR measured enrichment of H3K4me3 and H3K27me3 at the p15INK4b promoter after reactivation in KG-1 (A) and AML-193 cells (B). The enrichment of H3K4me3 (C) and H3K27me3 (D) measured at the p15INK4b promoter by quantitative PCR in clinical samples AML8, AML9, AML10, and AML11 patient blasts treated with DMSO (control), 5-aza-dC, or TSA. (C) *Significant increase in H3K4me3 enrichment compared with control treatment (P < .05, 1-way analysis of variance). Enrichment was calculated from ΔΔC_t averages of 3 independent experiments with error bars of SD. (E) ChIP-on-chip for enrichment of H3K4me3 (blue) and H3K27me3 (red) at INK4b-ARF-INK4a in DMSO control and 5-aza-dC plus TSA-treated KG-1 and AML-193 cells. (F) ChIP-on-chip for enrichment of H3K4me3 (blue) and H3K27me3 (red) at INK4b-ARF-INK4a in AML8 patient blasts treated with control DMSO, 5-aza-dC, or TSA. Normalized enrichment data (IP/input) are plotted on a log 2 scale.