Phylogenetic tree based on amino acid sequence of vertebrate P450s (represented here by the names of their respective CYP genes) involved in sterol synthesis and metabolism analyzed using the JTT distance (Jones et al., ’92). Sequences in the analysis included the enzymes 17α-hydroxylase/17,20-lyase (CYP17), 21-hydroxylase (CYP21), aromatase (CYP19), 24-hydroxylase (CYP24), 11β-hydroxylase (CYP11B1), aldosynthase (CYP11B2) and cholesterol side chain cleavage (CYP11A1). One thousand bootstrap pseudo-samples were used.