Definition: In this task, you're given a paragraph from the research paper and your task is to generate a suitable title for the research paper based on the given paper. Under 100 words is a good title length.
Input: The Mad1-Mad2 heterodimer is the catalytic hub of the spindle assembly checkpoint (SAC), which controls mitosis through assembly of a multi-subunit anaphase inhibitor, the mitotic checkpoint complex (MCC) [1, 2] . Mad1-Mad2 first catalyzes MCC assembly at interphase nuclear pores [3] , then migrates to kinetochores at nuclear envelope breakdown (NEBD) and resumes MCC assembly until bipolar spindle attachment is complete [1, 2] . There is significant debate about the factor(s) involved in targeting Mad1-Mad2 to kinetochores in higher eukaryotes [4] [5] [6] [7] [8] [9] . Through gene editing and livecell imaging, we found that the human Rod-Zw10-Zwilch (RZZ) complex is dispensable for cell viability and initial recruitment of Mad1-Mad2 to kinetochores at NEBD, but then becomes necessary to tether Mad1-Mad2 at kinetochores and sustain SAC arrest in cells challenged with spindle poisons. We also show that RZZ forms the mesh-like fibrous corona, a structural expansion of the outer kinetochore important for timely chromosome congression [10-13] once Mps1 phosphorylates the N-terminus of Rod. Artificially tethering Mad1-Mad2 to kinetochores enabled long-term mitotic arrest in the absence of RZZ. Conversely, blocking early RZZ-independent recruitment of Mad1-Mad2 eliminated the transient SAC response in RZZ-null cells. We conclude that RZZ drives structural changes in the outer kinetochore that facilitate chromosome biorientation and chronic SAC transduction, a key determinant of cytotoxicity during antimitotic drug therapy [14-16]. All rights reserved. No reuse allowed without permission. Results Recent studies have reached different conclusions about the specific roles and relative importance of Bub1 and the RZZ complex in targeting Mad1-Mad2 to kinetochores and transducing SAC arrest [4] [5] [6] [7] [8] . To interrogate RZZ function with maximum penetrance, we used AAV (adeno-associated virus)-and CRISPR-mediated gene editing to target the KNTC1 (Rod) locus in HCT116 cells, a diploid colorectal cell line ( Fig. S1A-C) . The resulting KNTC1 HF/-(hypomorph-flox) cells expressed Rod at ~20% of the wildtype level ( Fig. 1A -B and S1D) and exited mitosis prematurely when microtubule polymerization (nocodazole, 99 ± 6 min s.e.m.) or Eg5-dependent spindle bipolarity (S-trityl-L-cysteine (STLC), 193 ± 9 min s.e.m.) were inhibited, whereas wildtype cells never exited mitosis during the 16-hour timelapse (Fig. 1A-B) . To determine if complete loss of the RZZ complex is compatible with clonogenic survival, KNTC1 HF/cells were transduced with an adenovirus expressing Cre recombinase (AdCre) and subjected to limiting dilution.

The RZZ complex integrates spindle checkpoint maintenance with dynamic expansion of unattached kinetochores