Neighbor-joining trees for multi-domain Kunitz/BPTI proteins in ticks. Neighbor-joining trees for Two-KU (A), Three-KU (B), Four-KU (C) and Five-KU (D) proteins in ticks were reconstructed. The length of each branch is proportional to the estimated number of substitutions. Bar denotes 20% substitutions per site. The bootstrap values (> 50%) were shown in branches. The circle, square and triangle in the phylogram indicate the proteins from soft ticks, the genus Ixodes (hard ticks) and other hard ticks, respectively. The sequence name consists of 5 letters (3 from the genus and 2 from the species name) with the NCBI accession number.