TFBS enrichment in CGI probe loci segregating into each of the five methylation propagation categories.

TFBS frequencies were compared between each of the five sets of probe sequences separately from five methylation categories and the background sequences through Fisher exact test. Two different background sequences sets were used, as described above and in the text, to examine the specificity of TFBS enrichment to the CGI probe loci categorized into the five methylation maintenance categories. The p-value threshold was justified by a factor of 459×5, i.e. 0.05/459/5 = 2.2×10−5, based on 459 TFBS motifs and 5 comparisons.aBackground Sequence Set #1 = randomly generated promoter sequences (length/%GC-matched) to the CGI probe loci categorized into the five methylation classes.bBackground Sequence Set #2 = randomly selected microarray probe sequences (length/%GC-matched) uncategorized into the five methylation classes.