Scaffold protein involved in different aspects of polarized cell differentiation regulating epithelial and neuronal morphogenesis and T-cell polarization (PubMed:15182672, PubMed:16344308, PubMed:16965391, PubMed:18641685, PubMed:18716323, PubMed:19041750, PubMed:27380321). Via its interaction with CRTAM, required for the late phase polarization of a subset of CD4+ T-cells, which in turn regulates TCR-mediated proliferation and IFNG and IL22 production (By similarity). Plays a role in cell directional movement, cell orientation, cell sheet organization and Golgi complex polarization at the cell migration front (By similarity). Promotes epithelial cell layer barrier function via maintaining cell-cell adhesion (By similarity). Most probably functions in the establishment of apico- basal cell polarity (PubMed:16344308, PubMed:19041750). May function in cell proliferation regulating progression from G1 to S phase and as a positive regulator of apoptosis for instance during acinar morphogenesis of the mammary epithelium (PubMed:16965391, PubMed:19041750). May regulate cell invasion via MAPK-mediated cell migration and adhesion (PubMed:18641685, PubMed:18716323). May play a role in exocytosis and in the targeting of synaptic vesicles to synapses (PubMed:15182672). Functions as an activator of Rac GTPase activity (PubMed:15182672). {ECO:0000250|UniProtKB:A0A8P0N4K0, ECO:0000250|UniProtKB:Q80U72, ECO:0000269|PubMed:15182672, ECO:0000269|PubMed:16344308, ECO:0000269|PubMed:16965391, ECO:0000269|PubMed:18641685, ECO:0000269|PubMed:18716323, ECO:0000269|PubMed:19041750, ECO:0000269|PubMed:27380321}. Represses translation of the downstream SCRIB protein (PubMed:34535749). Translation of oSCRIB hinders SCRIB translation but does not completely abolish it, probably due to leaky scanning which allows the ribosome to bypass the weaker oSCRIB start codon and initiate translation at the stronger SCRIB start codon (PubMed:34535749). . This is the function of Ensembl gene identifier ENSG00000180900 (SCRIB, scribble planar cell polarity protein).