May play a role in the specification of neuronal cell types. May play a role in the dorsoventral specification of mesodermal cell fate. Shows a graded distribution in the primitive streak and in cells lateral to it. It is not detected in cells along the A-P axis of the embryo anterior to the primitive streak, except at 7.5 dpc when there is transient expression in the head process. The highest levels of expression are found within the proximal (posterior) portion of the primitive streak and cells near it, with expression levels decreasing more distally (anteriorly). Belongs to the even-skipped homeobox family.