Multifunctional protein that may affect its functions by regulating the activity of small GTPases, such as RAC1 and RALA (PubMed:12919680, PubMed:25074804, PubMed:26158537, PubMed:28869598). Required for normal progress through the cell cycle, both during interphase and during mitosis (PubMed:23388455, PubMed:12919680, PubMed:26158537). Required for the presence of normal levels of MAD2L1, AURKB and BIRC5 on inner centromeres during mitosis, and for normal attachment of kinetochores to mitotic spindles (PubMed:12919680, PubMed:26158537). Required for normal organization of the microtubule cytoskeleton in interphase cells (PubMed:23388455). Functions as guanine nucleotide exchange factor (GEF) for RALA (PubMed:26158537). Interferes with the activation of RAC1 by guanine nucleotide exchange factors (PubMed:25074804). Prevents accumulation of active, GTP-bound RAC1, and suppresses RAC1-mediated reorganization of the actin cytoskeleton and formation of membrane protrusions (PubMed:25074804, PubMed:28869598). Required for normal cellular responses to contacts with the extracellular matrix of adjacent cells, and for directional cell migration in response to a fibronectin gradient (in vitro) (PubMed:25074804, PubMed:28869598). Interacts with RAC1 (PubMed:12919680, PubMed:25074804, PubMed:28869598). Interacts with nucleotide-free and with GDP and GTP-bound forms of RAC1, with a slight preference for GDP-bound RAC1 (PubMed:25074804). Binds preferentially to the nucleotide-free form of RAC1 (PubMed:12919680). Interacts with CORO1C (PubMed:25074804). Interacts with microtubules (PubMed:12919680). Appears in the nucleus at G2, then concentrates at the inner centromere region of chromosomes during prophase. Redistributes to the midzone of the mitotic spindle during anaphase. Here, the protein covers the entire equatorial diameter from cortex to cortex (PubMed:12919680, PubMed:1939370, PubMed:7559776, PubMed:9914378). Colocalizes with cytoplasmic microtubules in interphase cells (PubMed:23388455). Colocalizes with RAC1 at the cell membrane (PubMed:25074804). Induced by TP53/p53 in response to oxidative stress and DNA damage. Its precise role in the regulation of RAC1 activity is under debate. Was originally proposed to function as a guanine nucleotide exchange factor for RAC1, but later publications indicate it attenuates RAC1 activation by guanine nucleotide exchange factors and prevents accumulation of active, GTP-bound RAC1 (PubMed:12919680, PubMed:25074804, PubMed:28869598). Conflicting results have also been reported regarding its preferential interaction with nucleotide-free RAC1, as opposed to GPD or GTP-bound RAC1 (PubMed:12919680, PubMed:25074804).