Figure 1

A phylogenetic tree of the B7 family. Sequence alignments were performed using ClustalW implemented in the AlignX module of Vector NTI version 9.1; alignments were imported into Mega 2.1 [47] and a phylogenetic tree was created using the neighbor-joining method (the setting for gaps and missing data was pairwise deletion; the distance method used was number of differences). Numbers at selected nodes indicate the percentage frequencies of branch association on the basis of 1,000 bootstrap repetitions. The scale bar indicates number of residue changes.