Maximum likelihood phylogenetic tree of zebrafish and human Clan 2 amino acid sequences. CYP1 family sequences are highlighted in red, while CYP2 sequences are highlighted in yellow. CYP2R1 and CYP2U1 are conserved. Zebrafish CYP2J co-orthologs clearly cluster with the human CYP2J, as do the zebrafish CYP2Ks with human CYP2W1, and zebrafish CYP2Ys with most of the remaining human CYP2 s. CYP1 evolution has been described elsewhere [58, 59]. Human (hs) sequences are red, zebrafish (zf) are blue.