FIG. 5.

Remethylation kinetics of CpG islands in T24 cells after 5-Aza-CdR treatment. T24 cells were treated with 5-Aza-CdR (5 × 10⁻⁷ M), and DNA was harvested every 1 to 3 days for up to 27 days. The population doubling time increased approximately 1.8-fold after 5-Aza-CdR treatment, as previously described (3). Only eight cell population doublings were attained between days 3 and 27 because cells transiently entered lag phase each time they were split and reseeded. Methylation of p16 exon 2, PAX-6 exon 5, c-ABL exon 11, and MYF-3 exon 3 was quantitated at each time point by the Ms-SNuPE technique, and the degree of remethylation at each locus was determined as the degree of methylation compared to the original level in untreated cells at 72 h. Methylation averages from three independent experiments are shown.