Plays a role in planar mitotic spindle orientation in retinal progenitor cells (RPCs) and promotes the production of symmetric terminal divisions (PubMed:26766442). Negatively regulates the mitotic apical cortex localization of GPSM2 (By similarity). Involved also in positive regulation of cell proliferation and tumor cell growth (By similarity). Interacts with a spindle orientation complex at least composed of GNAI1, GPSM2 and NUMA1. Interacts with GPSM2 (via TPR motifs); this interaction is required to prevent GPSM2 anchoring at the mitotic apical cortex and is inhibited in presence of NUMA1 in a dose dependent manner. Interacts with PARD3. Localized at the apical membrane during the M phase (PubMed:26766442). In horizontally retinal progenitor dividing cells, localized at the pole cortical region from prophase to telophase cells (PubMed:26766442). In vertically retinal progenitor dividing cells, not detected at the pole cortical region at any stage of mitosis (PubMed:26766442). Expressed in the retina (PubMed:26766442). Expressed in retinal progenitor cells and newly differentiated neurons but not in mature retinal cells (at protein level) (PubMed:26766442). Expressed in the embryonic retina from 14 to 17 dpc (at protein level) (PubMed:26766442). Expressed throughout neuroectoderm at 7.5 dpc (PubMed:15567712). The expression increases in rostral brain and caudal neuropore regions and decreases in hindbrain and spinal cord regions (PubMed:15567712). At 12.5 dpc the expression is found in undifferentiated neuroepithelium in ventricular zone, dorsal root ganglia and several non-neural tissues (PubMed:15567712). Truncated N-terminus.