Multifunctional protein that may affect its functions by regulating the activity of small GTPases, such as RAC1 and RALA. Required for normal progress through the cell cycle, both during interphase and during mitosis. Required for normal attachment of kinetochores to mitotic spindles. Required for normal organization of the microtubule cytoskeleton in interphase cells. Interferes with the activation of RAC1 by guanine nucleotide exchange factors. Prevents accumulation of active, GTP-bound RAC1, and suppresses RAC1-mediated reorganization of the actin cytoskeleton and formation of membrane protrusions. Required for normal cellular responses to contacts with the extracellular matrix of adjacent cells, and for directional cell migration. Interacts with RAC1. Interacts with CORO1C.