Adapter protein that provides a link between the endocytic membrane traffic and the actin assembly machinery. Acts as guanine nucleotide exchange factor (GEF) for cdc42, and thereby stimulates actin nucleation mediated by wasl and the arp2/3 complex (By similarity). Involved in endocytosis of activated egfr, and probably also other growth factor receptors (By similarity). Binds epn1 and epn2. Shuttles between the cytoplasm and nucleus in an XPO1/CRM1-dependent manner.