FIGURE 2.

Box plots of the different groups of exons for the predicted donor and acceptor splice sites, exon length, and the lengths of the upstream, downstream, or flanking introns. Exon skippability is based on the report published by Wilton and colleagues (Wilton et al. 2007). The median value is indicated by a broad vertical line which is located within a box that contains all values between the 25th and 75th percentiles. The outer ranges are depicted by dotted lines and bordered by small horizontal lines. Outlying values are indicated by small circles. Splice site values were calculated with the Berkeley Drosophila Genome Project software for human splice site prediction. The predicted acceptor splice sites were significantly higher for poor skippable exons as calculated with the Kruskal–Wallis signed rank sum test (P-value 0.04, indicated with an asterisk). No significant differences were observed for the other parameters, although there is a trend for predicted donor splice sites to be somewhat lower for highly skippable exons (P-value 0.2).