Cytoplasmic FMR1-interacting protein 1 is a protein that in humans is encoded by the CYFIP1 gene. CYFIP1 has been shown to interact with FMR1, to the exclusion of FXR1 and FXR2. It also forms part of the WAVE regulatory complex (WRC), and based on the crystal structure of the WRC it is believed CYFIP1 provides the binding site for the complex to Rac1.This protein also interacts with the Fragile X mental retardation protein (FMRP) and translation initiation factor 4E to inhibit protein translation. A large chromosomal deletion including this gene is associated with increased risk of schizophrenia and epilepsy in human patients. Reduced expression of this gene has been observed in various human cancers and the encoded protein may inhibit tumor invasion.