FBXO21 (F-Box Protein 21): FBXO21 is a gene that encodes a protein from the F-box family, which plays a crucial role in the ubiquitin-proteasome system responsible for protein degradation. It is involved in regulating key cellular processes such as the cell cycle and signal transduction. Dysregulation of FBXO21 can impact protein homeostasis and is significant in diseases marked by impaired protein turnover, including neurodegenerative disorders and cancers.