fig1

Figure 1. Different types of splicing events are shown schematically. (A) In constitutive splicing, all introns are spliced out and all exons are joined together to produce mRNA. (B) By alternative splicing, pre-mRNA can encode more than one mRNA isoform. Different isoforms can be generated by exon skipping/inclusion of alternative exons, the selection of alternative 5' or 3' splice sites, the retention of intron(s) or selection of the mutually exclusive exon(s). Exons and mRNAs are illustrated as boxes, while introns are represented by solid lines