Features of the RACE products. (a) Connectivity of detected transcripts to known exons/novel transcriptionally active regions (TARs). (b) Frequency of splice and unspliced rapid amplification of cDNA ends (RACE) products derived from known exons, novel TARs, and untranscribed regions. (c) Average microarray intensities of regions encoding spliced and unspliced RACE products. nontx, region not previously shown to be transcribed.