Involved in T-cell adhesion and p53/TP53-dependent induction of apoptosis. Does not bind RNA. 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 FMR1, FXR1 and FXR2 (By similarity). Interacts with FMR1 isoform 6; the interaction occurs in a RNA-dependent manner (PubMed:24658146). Interacts with RAC1 (activated form) which causes the complex to dissociate, releasing activated WASF1 (PubMed:15048733). The complex can also be activated by NCK1 (PubMed:15048733). Interacts with SHANK3; the interaction mediates the association of SHANK3 with the WAVE1 complex (By similarity). 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). Treatment with leptomycin-B triggers translocation to the nucleus (PubMed:17245118). Expressed in T-cells. Increased expression is observed in CD4(+) T-lymphocytes from patients with multiple sclerosis (at protein level). By p53/TP53. Partially edited. Editing appears to be brain-specific. The disease is caused by variants affecting the gene represented in this entry. Belongs to the CYFIP family. Extended N-terminus. Extended N-terminus.