Analysis of Glutathione-S-transferase (GST) protein family. Phylogenetic tree based on maximum likelihood analysis of Dermacentor variabilis midgut protein and published GST sequences. Transcripts identified in this analysis are in bold. Phylogenetic analysis was conducted on protein alignments using Tree Puzzle version 5.2. Values at the nodes represent calculated internal branch node support (1000 replications). D. variabilis (Dv), Ixodes pacificus (Ip), Sarcopte scabiei (Ss), Araneus ventricosus (Av), Rhipicephalus appendiculatus (Ra), R. (Boophilus) microplus (Bm), Haemaphysalis longicornis (Hl), Dermatophagoides pteronyssinus (Dp), and Psoroptes ovis (Po).