Figure 3.

Phylogenetic tree for all known A-type cyclins. Vertebrate A-type cyclins can be divided into two groups: somatic (A2) and germline (A1), whereas completion of the C. elegans and D. melanogaster genome-sequencing projects shows that there is only one A-type cyclin in these organisms. The alignment used for the construction of this phylogenetic tree is given in the additional data files. A. pectinifera, Asterina pectinifera; H. pulcherrimus, Hemicentrotus pulcherrimus; H. robusta, Helobdella robusta. The scale bar represents 0.1 substitutions per site.