Transcripts of a MouSDB3 cluster. (a) Partial image of MouSDB3 cluster number scl24819  displaying alternatively spliced transcripts. (b) Categorization of transcripts with respect to the cassette exon indicated by the arrow. This figure shows an example transcript for each of the three categories from the scl24819 cluster. Category 1, long transcript with cassette exon indicated by the arrow. Category 2, short transcript skips the cassette exon. Category 3, cassette exon is missing owing to a 5' truncation. Pink bars represent in-frame cassette exons. Green and blue bars represent exons with other types of splice variation. (Green are invariant, blue are length-variant exons). The red line represents intronic regions of the genome sequence.