Platelets express mRNA splice variants. Shown are coverage graphs of PEAR1 (A), tissue factor pathway inhibitor (TFPI) (B), and GFI1B (C) in platelets. (A) Note that there are 4 different Ensembl annotations listed underneath PEAR1. The red box is drawn around the second exon, which distinguishes the second annotation from the other 3 annotations. (B) The annotations for 2 major isoforms of TFPI, α (iso A) and β (iso B), are distinguished by their 3′ ends. Note that platelets are rich in isoform α but not isoform β. Exon 2 (exon 2 is very small, so it is difficult to see the annotation here), which can also be removed by alternative splicing, is also present in the platelet. (C) The arrow points to a putative novel exon of GFI1b. Annotations for an exon at this region are not present in any of the Ensembl, UCSC, or RefSeq databases. The red box outlines examples of paired reads that map from the unannotated novel exon to the known second exon suggesting that it is part of the GFI1B transcript. See it yourself: To see PEAR1, TFPI, and GFI1B in platelets via the UCSC Genome Browser, follow the Web link > access instructions for site 1 (see Table 1). For individual reads, follow the Web link > access instructions for site 2 (see Table 1). Search for PEAR1, TFPI, or GFI1B in the browser.