The p53 family of proteins is evolutionarily conserved in
animals from worms to humans. Invertebrate organisms like
C. elegans and D. melanogaster express a p53 homologue
(Cep-1 in C. elegans and Dmp53 in D. melanogaster) that
resembles p63 more than p53. Gene duplication gave rise to
a new p53-like protein in cartilaginous fish, while bony fish
and other vertebrates express all three family members.
Phylogenetic and functional analyses suggest that p63 is
the founding member of the family, followed by p73, and
finally by p53