Regulates the size of the shoot meristem by modulating the CLV3-WUS feedback loop. Can repress WUS but is under negative control by CLV3. Expressed in the shoot apex and young siliques. Detected in provascular and vascular tissue, but not in the vegetative meristem. In inflorescences, restricted to the base of the flower and to the vasculature of the stem and the pedicels, but absent from young flowers. Detected in the center of the inflorescence meristem. Expressed throughout development. Decreased expression in the shoot apex during the transition to flowering. Expressed in developing embryos from the early heart stage until torpedo stage. Belongs to the fantastic four family.