EMI1 (Cat No.:I026823), also known as FBXO5, is a cell cycle regulator that inhibits the Anaphase-Promoting Complex/Cyclosome (APC/C), a key E3 ubiquitin ligase complex. By binding to and inhibiting APC/C activators Cdc20 and Cdh1, EMI1 prevents premature degradation of mitotic regulators such as cyclins A and B, and geminin, thereby ensuring proper progression through S and G₂ phases. EMI1 is degraded at mitotic entry, allowing APC/C activation. Dysregulation of EMI1 expression can lead to genomic instability, mitotic errors, and has been linked to cancer progression.