Empty Spiracles Homeobox Protein 1 (EMX1)

When regional specification of major brain regions takes place in the mouse, the expression domains of the 4 genes appear to be continuous regions contained within each other, in the sequence Emx1 (smallest expression domain), Emx2, Otx1, Otx2 (largest expression domain). The Emx2 gene is expressed primarily in the dorsal telencephalon and partially in the diencephalon, and Emx1 expression is confined exclusively to the dorsal telencephalon. The first appearance of transcripts of the 4 genes is also sequential: Otx2 is expressed first, followed by Otx1 and Emx2, and finally by Emx1. The expression domains of the 4 genes in overlapping, nested regions suggests that the corresponding gene products may function in combinations to specify cell fates in the developing central nervous system.