Four isoforms of RefSeq gene Clta in mouse. This figure was generated using the CisGenome browser . At the top are shown the base positions in mouse chromosome 4 and exons as grey blocks. On the bottom are shown the four isoforms, with exons zoomed in. The tail of exon 1 of the first isoform is 6 bp less than that of the other three isoforms. The second isoform has 7 exons, while the third isoform misses both exon 5 (54 bp) and exon 6 (36 bp), and the fourth isoform misses exon 6.