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. They are members of a larger family of proteins that are involved in the regulation of a wide variety of cellular processes (including the cell cycle, immune responses, signaling cascades and developmental events) through the targeting of proteins, such as cyclins, cyclin-dependent kinase inhibitors, I?B-? and ∫-catenin, for proteasomal degradation. FBL12 (F-box and leucine-rich repeat protein 12), also designated FBXL12, is a 326 amino acid protein that contains one F-box domain, five LRR (leucine-rich) repeats and exists as two alternatively spliced isoforms. FBL12 interacts with both Skp1 and CUL-1, and is encoded by a gene that maps to human chromosome 19p13.2.