Downstream effector molecule involved in the transmission of signals from tyrosine kinase receptors and small GTPases to the actin cytoskeleton. Promotes formation of actin filaments. Part of the WAVE complex that regulates lamellipodia formation. The WAVE complex regulates actin filament reorganization via its interaction with the Arp2/3 complex (By similarity). Binds actin and the Arp2/3 complex. Interacts with BAIAP2. Component of the WAVE2 complex composed of ABI1, CYFIP1/SRA1, NCKAP1/NAP1 (NCKAP1l/HEM1 in hematopoietic cells) and WASF2/WAVE2. Directly interacts with BRK1. Interacts with human cytomegalovirus protein UL135. Interacts with FNBP1L (via the SH3 domain). At the interface between the lamellipodial actin meshwork and the membrane. Binds and activates the Arp2/3 complex via the C-terminal domain. Interacts with actin via the WH2 domain (By similarity). Belongs to the SCAR/WAVE family.