Diversification of TF Paralogs Figure 7. Tissue coherence versus binding site motif similarity between TF paralogs. (a) The 95 paralogous TF pairs are sorted in decreasing order of their DNA binding site motif similarity. The normalized and total number of shared tissues in which each TF is gene expressed at a level above the tissue-median are color coded, and the resulting figure legend indicates the number of tissues. (b) The trend of the normalized and total number of shared tissues for the paralogous TF pairs using a cubic smoothing spline with 4 degrees of freedom. Paralogs with high binding similarity tend to have few common tissues in which they are expressed, for both normalized and total. Kendall tau Correlation = 20.156, p-value = 0.03. doi:10.1371/journal.pone.0002345.g007 PLoS ONE | www.plosone.org 8 June 2008 | Volume 3 | Issue 6 | e2345