Clinical response is not uniformly associated with p15^INK4B methylation reversal. (A) Methylation reversal in clinical responders. DNA BSS of 27 CpG sites in the promoter region of p15^INK4B in 2 clinical responders (patients 10 and 16). Patient 16 showed reversal of methylation at days 15 and 29 (left panel), whereas patient 10 (right panel) did not show methylation reversal by BSS. (B) Reversal of methylation of p15^INK4B in clinical nonresponders. DNA BSS of 27 CpG sites in the promoter region of p15^INK4B on days 0, 15, and 29 of therapy showed methylation reversal in both clinical responder and nonresponder (patients 7 and 3, respectively). Patient 7 showed methylation reversal at day 29 only. ∘ indicates unmethylated CpGs and • indicates methylated CpGs. The solid line labeled MSP product marks the start and end position of the CG sites of the MSP amplicon. The numbers below the horizontal bar describe the position of the CpGs relative to the transcription start site (+1). %M indicates percentage methylation calculated by dividing the number of • by the number of ∘ (270) and multiplied by 100.