Methylation differences between paired tumor tissues and neighboring morphologically normal tissues. Differences in methylation as measured by bisulfite pyrosequencing are plotted for all paired samples from (A) colon, (B) bladder, (C) prostate, and (D) stomach. The red and black frames at the top of each panel enclose the results from the global methylation assay and the average methylation of all individual LINE-1 loci, respectively. Methylation differences between < −20, −20 to −10, −10 to 10, 10 to 20 and >20 are marked as blue, turquoise, black, orange, and red symbols, respectively. The variance of methylation differences is shown to the right of each locus. Values in parenthesis correspond to the total number of samples (black, left), number of samples below the −10 threshold (blue, center) followed by number of samples above the +10 threshold (red, right). Var.: variance.