The IRXA group includes Irx1, Irx2 and Irx4; the IRXB group is comprises Irx3, Irx5 and Irx6. Irx1 and Irx2 are both widely expressed during development in the lung epithelium and also in the ventricular septum. Irx1 and Irx2 also play a role in digit formation (E11.5-E14.5). The Irx gene family members are each expressed in a distinct pattern during mouse heart development. Specifically, Irx1 and Irx2 are expressed in the ventricular septum and Irx3 is expressed in the ventricular trabeculated myocardium. In addition, Irx4 is expressed in the linear heart tube and the AV canal; .
Homeodomain protein IRXA1; Iroquois homeobox protein 1; Iroquois-class homeodomain protein IRX-1; IRXA1