Figure 6
From: Insights into the evolution of the ErbB receptor family and their ligands from sequence analysis
Phylogenetic relationship of the ErbB receptors. Shown is a tree generated using neighbor joining with p-distance correction of protein sequences in MEGA version 3.1 [61]. Shown are the bootstrap percentages for the split between invertebrate and vertebrate receptors. Similar trees were generated using different methods of distance correction. The invertebrate receptors lead into the vertebrate receptors separating ErbB3 and ErbB4 from EGF receptor and ErbB2. This structure suggests three gene duplication events, depicted by the filled circles, the first generating EGF receptor/ErbB2 and ErbB3/ErbB4 progenitors. Two more gene duplication events generated the four receptors seen in the vertebrates.