FBXO29, also designated F-box/WD repeat-containing protein 8 (FBXW8), is a 598 amino acid protein that contains one 40 amino acid F-box region, making it a member of the F-box family. FBXO29 also contains five WD repeats. F-box proteins are critical components of the SCF (Skp1-CUL-1-F-box protein) type E3 ubiquitin ligase complex and are involved in substrate recognition and recruitment for ubiquitination. F-box proteins are members of a large family that regulates cell cycle, immune response, signaling cascades and developmental programs by targeting proteins, such as cyclins, cyclin-dependent kinase inhibitors, IkB-a and ∫-catenin, for degradation by the proteasome after ubiquitination. Functioning as a component of the SCF complex, FBXO29 is thought to recognize and bind to select phosphorylated proteins, thereby promoting their ubiquitination and subsequent degradation. FBXO29 exists as two isoforms as a result of alternative splicing events.