Exon-level microarrays were used to quantify expression levels of fully annotated coding sequences, EST-predicted exons, and bioinformatically predicted exons across the genome. These data allow direct inferences about expression levels of specific exons. By averaging sets of exons it is also possible to estimate expression levels for transcript species (Figure 1, top panel). While the exon-level expression data do not allow inference about the representation of specific (full) transcripts resulting from a given alternative splicing event, they do reflect splicing events in how they influence the proportion of transcripts with and without a given exon (Figure 1, middle and bottom panels).
