P53, p63, and p73 have similar features in their gene structures and functions but have also diverged evolutionarily. The p53 family evolved from a p63/p73 ancestor gene in invertebrates. P53 diverged from p63/p73 with a gene duplication in the cartilaginous fish. P63 and p73 differentiated from each other in bony fish. These genes developed different functions and structures throughout their evolutionary divergence (TP73L, p73, p53) .
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^ abcLevine, A. J., V. A. Belyi, P. Ak, E. Markert, H. J. Wang, W. W. Hu, and A. Puzio-Kuter. (2010). "The origins and evolution of the p53 family of genes". Cold Spring Harbor Perspectives in Biology 2.