Gene expression in relation to promoter and gene body methylation. Box plot showing average expression of unmethylated genes, genes with methylated promoters, and genes with methylated gene bodies was compared for each tissue type using gene expression data from a Nimblegen microarray. Each box encloses the middle 50% of the distribution (25th percentile - 75th percentile, or interquartile range (IQR)). Lines in boxes mark medians. Lines extending from boxes mark minimum and maximum values that fall within 1.5 times the IQR.