Unrooted distance neighbor-joining tree of P450 CYP4 genes from the genome of Culex pipiens quinquefasciatus . Greater than 70% support in 1000 bootstrap replications is indicated at the corresponding nodes. Genes undetected in DGE libraries are shown in bold. P450s were named by the P450 nomenclature committee (http://drnelson.uthsc.edu/CytochromeP450.html). Genes with v1 and v2 designation are very recent duplications and have not yet been assigned individual gene names.