Genome structure of Runx1 in various species. (A) Exon-intron structure of human RUNX1 and mouse Runx1. Genome sequences of Runx1 were collected from the GenBank database (NCBI). Boxes represent exons. Black boxes represent coding sequences. (B) Sequence homology of human RUNX1a intron 6 and exon 7A and their counterparts in other species. Top, Junction of human RUNX1a intron 6 and exon 7A. Bottom, Poly A signal and poly A site. Shaded areas show the common sequences. (C) Amino acid sequence encoded by human RUNX1a exon 7A and its counterparts in other species. Shaded area shows the common sequences. *, The end of the protein sequence. (D) Alternatively spliced isoforms of mouse Runx1. Boxes represent exons. Black boxes represent coding sequences. Gray box in Runx1bEx6e shows the part of extended exon 6 located in intron 6. P1, distal promoter; P2, proximal promoter.