FBOX21 (F-Box Protein 21): FBOX21 is a member of the F-box protein family, which are key components of the ubiquitin-proteasome system responsible for protein degradation. This system is essential for regulating protein levels within the cell and influences processes such as cell cycle progression, signal transduction, and apoptosis. FBOX21 specifically helps target proteins for degradation, supporting cellular homeostasis. Dysregulation of FBOX21 can contribute to diseases, including cancers, where abnormal protein accumulation or degradation promotes disease development.