Transcription factor required for quiescent center cells specification and maintenance of surrounding stem cells, and for the asymmetric cell division involved in radial pattern formation in roots. Essential for cell division but not differentiation of the ground tissue. Regulates the radial organization of the shoot axial organs. Restricts SHR movment and sequesters it into the nucleus of the endodermis (By similarity). Interacts with SHR1, but not with SHR2. Belongs to the GRAS family.