Phylogenetic analyses of E2F1-6 and E2F7/8 family genes in metazoan. Maximum likelihood analysis was conducted using Phyml program, and Bayesian analyses were carried out using MrBayes 3.1. Both methods produced nearly identical topologies. Black numbers above branches indicate ML bootstrap support (only greater than 50% values are labeled), and red numbers above branches indicate Bayesian posterior probabilities (only these key branches are labeled). The scale bar shows the number of substitutions per site. The detail information for protein names used in this figure can be found in materials and methods section. The accession numbers and sequence of all these proteins are listed in additional File 1. (A) Phylogenetic analyses of E2F1-6 family, and E2F-Mb (gi:167523471) was used as the outgroup; (B) Phylogenetic analyses of E2F7/8 family, and E2F7/8-Mb (gi:167517423) was used as the outgroup.