ANAPC15 (anaphase promoting complex subunit 15) is a component of the APC/C, a cell cycle-regulated E3 ubiquitin ligase that controls mitotic progression 1. The APC/C catalyzes assembly of branched 'Lys-11'-/'Lys-48'-linked ubiquitin chains on target proteins 2. ANAPC15 plays a specialized role in spindle assembly checkpoint (SAC) responsiveness by promoting turnover of the mitotic checkpoint complex (MCC) from the APC/C 1. Specifically, ANAPC15 is required for CDC20 autoubiquitylation and degradation when the SAC is satisfied, facilitating MCC disassembly and enabling rapid APC/C reactivation upon kinetochore attachment 34. This function is critical for timely anaphase initiation but is dispensable for APC/C substrate ubiquitylation activity itself 3. ANAPC15 is located near the APC/C's MCC binding site and works in concert with other factors like TRIP13 to coordinate mitotic exit 4. Beyond its canonical cell cycle role, ANAPC15 has emerged as a potential diagnostic biomarker in rheumatoid arthritis, with anti-ANAPC15 autoantibodies detected in 41.8% sensitivity and 91.5% specificity among RA patients 5, particularly in ACPA-negative disease. This dual relevance—in cell cycle control and autoimmune pathology—highlights ANAPC15's biological significance.