Negatively regulates RAC1 signaling and RAC1-driven cytoskeletal remodeling (PubMed:31285585, PubMed:30250061). Regulates chemotaxis, cell migration and epithelial polarization by controlling the polarity, plasticity, duration and extent of protrusions. Limits Rac1 mediated activation of the Scar/WAVE complex, focuses protrusion signals and regulates pseudopod complexity by inhibiting Scar/WAVE-induced actin polymerization (PubMed:30250061). Protects against Salmonella bacterial infection. Attenuates processes such as macropinocytosis, phagocytosis and cell migration and restrict sopE-mediated bacterial entry (PubMed:31285585). Restricts also infection mediated by Mycobacterium tuberculosis and Listeria monocytogenes (By similarity). Involved in the regulation of mitochondrial dynamics and oxidative stress (PubMed:29059164). Interacts with RAC1 (GTP-bound form preferentially). Protein levels are negatively regulated by Salmonella. Ubiquitinated at Lys-74 upon Salmonella bacterial infection. Belongs to the CYRI family.