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Phylogenetic tree of human, guinea pig, mouse, rat and hamster ABCB1 inferring that guinea pig is closest to human and that these share a common historical evolution with Abcb1a of mouse, rat and hamster, whereas Abcb1b evolved separately. Phylogenetic tree created using http://www.phylogeny.fr/version2_cgi/simple_phylogeny.cgi and based on protein sequences. Branch length is proportional to the number of substitutions per amino acid site.
