Phylogenetic relationship of serpins in selected vertebrates and invertebrates. Protein sequences of available serpins in sea squirt, fly, and worm, also of typical serpins in human and mouse were used for this analysis. Label prefixes "Hs", "Mm", "worm", "squirt" and "fly" were used for genes for human, mouse, worm, sea squirt and fly respectively. This is a bootstrap consensus tree based on 500 replicates. The numbers on nodes are bootstrap values.