Phylogenetic relationship of vertebrate β-defensins. The tree was constructed by the neighbor-joining method and the reliability of each branch was assessed by using 1000 bootstrap replications. Numbers on the branches indicate the percentage of 1000 bootstrap samples supporting the branch. Only branches supported by a bootstrap value of at least 50% are indicated. Chicken β-defensins are highlighted in yellow. Abbreviations: BNBD, bovine neutrophil β-defensin; LAP, lingual antimicrobial peptide; EBD, enteric β-defensin; TAP, tracheal antimicrobial peptide; PBD, porcine β-defensin; DEFB/Defb, β-defensin; Gal, Gallinacin; GAPDH, glyceraldehyde-3-phosphate dehydrogenase.