FBOX21 (F-Box Protein 21): FBOX21 is a member of the F-box protein family, which are crucial components of the ubiquitin-proteasome system responsible for protein degradation. This system is vital for regulating protein levels within the cell, affecting processes such as cell cycle progression, signal transduction, and apoptosis. FBOX21 specifically aids in targeting proteins for degradation, thereby supporting cellular homeostasis. Dysregulation of FBOX21 can contribute to diseases, including cancers, where abnormal protein accumulation or degradation drives disease progression.