Chromosomal preference and dispreference for each TFBS class. (A) Rows represent the 16 chromosomes labelled I to XVI, and each column represents the μ log10 P value (negative sign indicates that the number of TFBSs is higher than expected (i.e. preference), while positive sign indicates that the number of TFBSs is lower than expected (i.e. dispreference)) significance profile of a specific TFBS class. For each of the four TFBS classes, we first counted the numbers of TFBSs that are on each of the 16 chromosomes and on the other 15 chromosomes, respectively. We next counted the total numbers of all TFBSs that are on each of the 16 chromosomes and on the other 15 chromosomes, respectively. By using chi-test to evaluate the overlap in membership of specific class of TFBSs (observed occurrence) with the collection of all TFBS classes (expected occurrence) that reside on the specific chromosome and on the other chromosomes, we evaluated whether the particular TFBS class shows a strong preference to reside or is uniformly distributed on specific chromosome. P values were calculated using the CHITEST formula in Excel. (B) The favoured and disfavoured chromosomes for each of the 4 TFBS classes. The top column denotes the 4 TFBS classes, and the bottom column denotes the 16 chromosomes. Red and green lines connecting the two columns mean that the TFBS classes tend to preferentially reside or avoid residing on a particular chromosome (P < 0.01), respectively.