F-box only protein 4 (FBXO4)

F-box only protein 4 (FBXO4) is a member of the F-box protein family, characterized by an F-box motif that mediates interaction with SKP1 as part of the SCF (SKP1–Cullin1–F-box protein) E3 ubiquitin ligase complex[1][2][3]. FBXO4 is specifically involved in the ubiquitin-mediated degradation of several key regulatory proteins, including cyclin D1, Fxr1, p53, Mcl-1, ICAM-1, and PPARγ, impacting cell cycle progression, tumor suppression, senescence, and cellular proliferation[3][4][5]. It is commonly regarded as a tumor suppressor, with loss-of-function mutations or reduced expression implicated in oncogenesis and cancer progression, notably in esophageal cancer, breast cancer, and head and neck squamous cell carcinoma[2][3][4][5]. There are multiple isoforms of FBXO4, with differential activities and cellular localizations[3]. The protein's regulation is multifaceted, encompassing transcriptional, translational, and post-translational mechanisms, as well as autoregulatory feedback with some of its substrates (notably Fxr1)[5]. Due to its central role in cell cycle control and cancer biology, FBXO4 is under investigation as a potential therapeutic target and diagnostic/prognostic biomarker[3][4][5].

Other names

FBXO4F-box protein 4FBX4F-box only protein 4F-box protein Fbx4

Drugs targeting FBXO4 (theoretically or in preclinical research) would modulate the degradation of its substrates (e.g., cyclin D1, Fxr1, p53, Mcl-1, ICAM-1, PPARγ) via ubiquitin-proteasome pathway, affecting processes such as cell cycle arrest, apoptosis, or senescence[3][4][5].