Analysis of the expression level in the indicated gene sets. A. The median, 25% and 75% quartiles of tissue average expression for each gene sets. B. The gene sets were divided into short (intron <8000 nt, white box) or long genes (intron >8000 nt, grey box), and the median, 25% and 75% quartile of the avarage expression for each gene set is shown. C. The p-values of the differences in the median value between each two gene sets as indicated. NS is non-significant difference (p > 0.05).