Figure 3.

Orientation requirement for the effectiveness of CREs. Genes with non-palindromic CREs in either forward (on the sense strand) or reverse (antisense) orientation in the 1-kb upstream sequence from the transcription start site were tested: where the population of genes with the element is significantly (*; p-value < 0.05) more induced or suppressed than expected in both orientations, the element is considered to be bidirectional; where only one orientation of CRE shows significantly different expression than expected, then it is considered orientation-sensitive or unidirectional.