Fig. 2
From: Are there gap junctions without connexins or pannexins?
GJ proteins evolution. Connexin (blue) and pannexin (red) presence (+) or absence (−) in the multicellular animal main taxonomic groups is indicated in simplified phylogenetic tree. The blue arrowhead points out a hypothetical connexin acquisition event in Chordate evolution. The red arrowhead shows a hypothetical event of pannexin loss at the base of Echinodermata/Hemichordata’s sister group branch