Figure 5. DNMT1 regulates p53 by modifying CpG methylation. (A) Relative methylation of the promoters of the senescence-associated genes p53, p21, and p16, in sun-exposed or non-sun-exposed human skin samples, * vs non-sun exposed, P < 0.05. (B) Relative methylation of the p53 promoter region in untreated HDFs(a), UVA-irradiated HDFs (b), and UVA-irradiated HDFs over-expressing DNMT1(c). Each horizontal line represents an individual DNA molecule, and the circles represent CpG dinucleotides. Filled circles: methylated CpGs; open circles: unmethylated CpGs. Numbers at the bottom of the figure indicates CpG position.