Summary of rooted phylogenies of families of genes including members on three of the four human Hox-bearing chromosomes. In each case, the bootstrap confidence level (BCL) of the internal branch is indicated in parentheses. Names of gene families are abbreviated as in Table 1. (INTA-PS1) Vertebrate integrin α chains in the subfamily related to Drosophila integrin α-PS1; (INTA-PS2) vertebrate integrin α chains in the subfamily related to Drosophilaintegrin α-PS2 (Hughes 2001). For NOS phylogeny, see Hughes (1998b).