Bootstrap replicates of the descriptive statistics related to the variation in gene expression. In total, 27 pairs of adjacent normal and tumor samples with 12 un-paired samples were used in this analysis. A total of 39 blocks of microarray samples were used for the block bootstrap. The re-sampling process was repeated 1,000 times to obtain 1,000 bootstrap replicates of the minimum (green color), first quartile (red color), median (black color), third quartile (blue color) and maximum (cyan color) expression levels for each gene. Each result was ranked by the order of medians. The bootstrap replicates of all five statistics for DDX5 expression remain roughly constants, but those for GAPDH expression vary greatly.