Figure 7. Phylogenetic tree of β₂AR haplotypes with phenotypic annotation.

Shown is a phylogenetic tree constructed as indicated in Methods with the 8 β₂AR haplotype sequences. Shown are the expression phenotypes (I, increased; R, reference) and the dual phenotypes that incorporate expression and downregulation (denoted A, B, C from Figure 6). L1 and L2 represent the two ancestral lineages, while L2(1) and L2(2) are lineages from L2.