HuEx and U133 arrays detect spatially distinct mRNA isoform changes. Comparison of SplicerEX-predicted mRNA isoform changes detected using the U133 versus HuEx array platforms. Alternative 5′-transcript initiation and internal events were preferentially detected by the HuEx array. Internal events were primarily composed of cassette exons, but could also include intron retention and alternative 5′- or 3′-exon definition. Alternative 3′-TE choice and tandem 3′ UTRs were preferentially detected by the U133 array. Alternative 3′-TE choice occurred via alternative polyadenylation or alternative 3′-splice site selection. Tandem 3′ UTRs universally resulted in shortening or lengthening of mRNA 3′-UTR length.
