Expression and sequence conservation of extended probesets. A. An example of two probe sets with concordant expression profiles. Expression of the 2 correlating probe sets is shown across all 70 microarrays, which are 3-5 biological replicates from 22 different tissues. B. Genomic context of the probe sets shown in panel A. Note that transcriptional direction is from right to left (negative strand). The red probe set (1416008_at) is targeting an intergenic region, which according to our algorithm likely is an extended 3'UTR of the upstream gene Sat1b. The region immediately downstream of the known 3' UTR; this region is highly conserved and contains 2 predicted polyA signals (indicated by stars). C. Conservation score distribution of mouse 3' UTR regions (green) and intergenic regions (red). Black arrow indicates the conservation score of the extended regions.