Figure 4. Schematic views of Pax-6 variants from metazoan animals.

Squid was shown to have Pax-6 splicing variants involved in the eye formation processes. Three Pax6 genes are known to be involved in insect compound eye development. Although it is difficult to determine ey, toy and eyg duplication events precisely, toy and eyg are known to play roles independent to ey in compound eye formation in flies. In mammals, it has been demonstrated that at least four forms of Pax-6 are generated by alternative splicing and sumoylation. UBA, urbilaterian ancestor.