Figure 2.
Two types of novel AS exons identified in this study. Shown in the figure is the mapping of a mouse EST to the human genome. (A) Cassette-on exon. eh1 and eh2 are well-annotated human exons. em1, em2, and em3 are segments of a mouse EST sequence, where em1 and em3 respectively overlap with eh1 and eh2, and em2 matches the human intron between eh1 and eh2. em2 is therefore identified as a potential novel cassette-on exon of human. (B) Retained intron. The matching EST segment is identified as a retained intron, if it covers a whole intron between two adjacent human exons.