Multiple sequence alignment of representative Aurora-A (AurA), Aurora-B (AurB), and Aurora-C (AurC) kinases, and their homologs (Air1, Air2, ARK1 and Ipl1). N-terminal regions which are species-specific and could not be accurately aligned are excluded, although the numbering of residues begins at the starting amino acid for that particular peptide. Progressive darker shading indicates conservation of amino acid residues in 60%, 80% and 100% of the sequences, respectively. Dark line at the top of the sequence blocks indicates those regions used in the phylogenetic analyses (Also see additional file 1 and 2). Species include Homo sapiens (hosa), Mus musculus (mus), Danio rerio (dare), Takifugu rubripes (taru), Xenopus laevis (xela), Ciona intestinalis (ciin), Drosophila melanogaster (drme), Caenorhabditis elegans (cael), Saccharomyces cerevisiae (sace) and Schizosaccharomyces pombe (scpo). The program CLUSTALW  was used to constructed the initial alignment which was subsequently refined manually.