Reactivation of p15INK4b expression and loss of DNA methylation after treatment with DNMT or HDAC inhibitors. (A) Quantitative RT-PCR analysis of p15INK4b expression in KG-1, KG-1a, and AML-193 cells after reactivation with 5-aza-dC and/or TSA. (B) Quantitative RT-PCR for p15INK4b, p14ARF, and p16INK4a expression in KG-1cells after reactivation with 5-aza-dC and/or TSA. (A-B) *Increase in expression relative to control (P < .05, 1-way analysis of variance). (C) Quantitative RT-PCR for p15INK4b expression in AML patient blasts treated with 5-aza-dC or TSA. Quantitative RT-PCR data in both cell lines and clinical samples were normalized to control cells and calculated from ΔΔC_t averages of 3 independent experiments with error bars of SD. *Significant increase in expression in cells treated with a combination of 5-aza-dC and TSA compared with cells treated with 5-aza-dC alone (P < .05, 1-way analysis of variance). (D) Bisulfite sequencing of the p15INK4b CpG island in individual clones from control and treated KG-1, AML-193, and AML8 blasts after treatment with 5-aza-dC and/or TSA. Filled circles represent percentage DNA methylation at individual CpG positions from 10 independently sequenced clones (● represents ≥ 50% methylcytosine; , 10%-49% methylcytosine).