Essential protein involved in the regulation of cell division planes during embryogenesis which defines cell patterning, especially longitudinal division planes of the proembryo, probably via the regulation of embryo patterning genes expression patterns. Preferentially expressed in dividing cells in a variety of tissues and meristematic regions. Expressed in young proliferating tissues, such as root tips, meristems, young leaves and floral buds (PubMed:17616738). Also observed in the mature embryo sac of the female gametophyte (PubMed:17616738). In embryos, first observed at low levels very early in the proembryo, accumulates strongly in embryos with more than eight cells and remains at high levels until cell division ceased prior to dormancy (PubMed:17616738). In seedlings, concentrated at the developing apex in all root tips and later in the developing flowers of the inflorescence (PubMed:17616738). Defective embryo arrested at preglobular stage characterized by aberrant cell division planes leading to an abnormal cell patterning; longitudinal division planes of the proembryo are frequently replaced by transverse divisions and less frequently by oblique divisions (PubMed:17616738). Altered embryo patterning genes expression patterns (PubMed:17616738). Truncated N-terminus.