F-box only protein 5 (FBXO5)

F-box only protein 5 (FBXO5), also known as early mitotic inhibitor 1 (EMI1), is a member of the F-box protein family functioning as a substrate recognition subunit of the SCF E3 ubiquitin ligase complex. FBXO5 plays a critical role in regulating the cell cycle by inhibiting the anaphase-promoting complex/cyclosome (APC/C), thereby ensuring proper transition into S and M phases. Dysregulation and overexpression of FBXO5 are frequently observed in multiple human cancers, where it contributes to uncontrolled cell proliferation, genomic instability, and poor clinical outcomes. FBXO5 is considered a promising therapeutic target and prognostic biomarker in oncology research due to its foundational role in cell cycle control and tumorigenesis[1][2].

Other names

EMI1F-box protein 5Fbx5early mitotic inhibitor 1early fission inhibitory protein 1

Inhibitors (theoretical or preclinical) would act by blocking FBXO5, leading to release of APC/C inhibition, altered cell cycle progression, and possibly genomic stabilization[2]. FBXO5 indirectly modulates sensitivity to PARP inhibitors through regulation of RAD51 degradation and homologous recombination in breast cancer[2].