CYFIP1/2 belongs to the CYFIP family and is involved in T-cell adhesion and p53-dependent induction of apoptosis. CYFIP1 contains 1,253 amino acids and shares 88% sequence identity with CYFIP2. CYFIP1 and CYFIP2 are members of a highly conserved protein family and share approximately 99% sequence identity with their mouse orthologs. CYFIP1 has been shown to interact with the small GTPase RAC1, which is implicated in development and maintenance of neuronal structures. Consistent with FMRP and RAC1 localization in dendritic fine structures, CYFIP1/2 are present in synaptosomal extracts. This antibody can recognize both CYFIP1 and CYFIP2.