Adapter protein that links membrane-bound small G-proteins to cytoplasmic effector proteins. Necessary for CDC42-mediated reorganization of the actin cytoskeleton and for RAC1-mediated membrane ruffling. Involved in the regulation of the actin cytoskeleton by WASF family members and the Arp2/3 complex. Plays a role in neurite growth. Acts syngeristically with ENAH to promote filipodia formation. Plays a role in the reorganization of the actin cytoskeleton in response to bacterial infection. Participates in actin bundling when associated with EPS8, promoting filopodial protrusions (By similarity). Homodimer. Interacts with CDC42 and RAC1 that have been activated by GTP binding. Interacts with ATN1, ADGRB1, DIAPH1, EPS8, SHANK1, SHANK2, SHANK3, TIAM1, WASF1 and WASF2. Interacts with ENAH after recruitment of CDC42 (By similarity). Detected throughout the cytoplasm in the absence of specific binding partners. Detected in filopodia and close to membrane ruffles. Recruited to actin pedestals that are formed upon infection by bacteria at bacterial attachment sites (By similarity). The IMD domain forms a coiled coil. The isolated domain can induce actin bundling and filopodia formation. In the absence of G-proteins intramolecular interaction between the IMD and the SH3 domain gives rise to an auto-inhibited state of the protein. Interaction of the IMD with RAC1 or CDC42 leads to activation (By similarity). The SH3 domain interacts with ATN1, ADGRB1, WASF1, WASF2, SHANK1, DIAPH1 and ENAH. Phosphorylated on tyrosine residues by INSR in response to insulin treatment.