The mature domains of each molecule were aligned using ClustalX [1]. The alignment was then processed with Protdist and Neighbor using the Dayhoff PAM Matrix [2]. The tree used as the basis for the dendrogram was created using TreeView [3]. The branches of the phylogenetic tree represent divergence of each branch member from a common ancestor. The branch lengths reflect the number of amino acid changes between each protein and that hypothetical ancestor, and imply how much time has passed since the divergence.