Figure 9
Comparison of the pax4 and arx regulatory circuits in zebrafish and mouse. A mutual repression between arx and pax4 is present in both species and α-cell differentiation relies on Arx activity. While PAX4 is required for β- and δ-cell formation in mouse, it is dispensable in zebrafish for that function. In zebrafish, Arx and Pax4 can repress their own expression. All interactions can be either direct or indirect.