Involved in T-cell adhesion and p53-dependent induction of apoptosis. Does not bind RNA (By similarity). As component of the WAVE1 complex, required for BDNF-NTRK2 endocytic trafficking and signaling from early endosomes (By similarity). Component of the WAVE1 complex composed of ABI2, CYFIP2, BRK1, NCKAP1 and WASF1/WAVE1. Interacts with RAC1 (activated form) which causes the complex to dissociate, releasing activated WASF1. The complex can also be activated by NCK1. Interacts with SHANK3; the interaction mediates the association of SHANK3 with the WAVE1 complex. Interacts with FMR1; the interaction occurs in a RNA-dependent manner. Interacts with FXR1 and FXR2. Interacts with TMEM108 (via N-terminus); the interaction associates TMEM108 with the WAVE1 complex (By similarity). Highly expressed in the perinuclear regionand enriched in synaptosomes (By similarity). Belongs to the CYFIP family.