UCSC Genome Browser view of the human–mouse sequence alignment in theST7 region. The Browser tracks provide different types of information on the ST7 gene, in this case showing the region from exon 3 through exon 9, as thin rectangles on the track beneath “RefSeq Genes“. The two diagrams for ST7 represent the two isoforms, a and b. The direction of transcription is indicated by the light blue arrows. The next three tracks (Spliced ESTs, Human ESTs, Nonhuman mRNAs) show evidence of transcription into stable mRNA. The Mouse Cons track plots a log-likelihood score that gives the probability that an aligned segment is under selection, adjusted for the neutral substitution rate measured in nearby ancestral repeats. The positions of blastz alignments are plotted on the Blastz Best Mouse track, and nucleotide-level alignments can be obtained by clicking on this track. Regions that align with Fugu rubripesare shown on the Fish Blat track, followed by repeats as identified byRepeatMasker. The position of the highly conserved noncoding sequence in intron 8 of ST7 is indicated by the red box. Note that it has a score on the MouseCons track of 4.0, meaning that it is 10,000 times more likely to be under selection than to be under evolutionary drift.