KNL1 (kinetochore scaffold 1) is an evolutionarily conserved outer kinetochore protein essential for accurate chromosome 15. As a key component of the KMN network, KNL1 serves as a multifunctional docking platform that mediates microtubule-kinetochore interactions and recruits spindle assembly checkpoint (SAC) components 12. KNL1 directly recruits MAD2L1, BUB1, and BUB1B to unattached kinetochores, with the KNL1-Bub3-Bub1 pathway essential for SAC activation when kinetochores are misaligned 3. The protein contains multiple interaction motifs (RVSF, SILK, MELT, KI) that facilitate recruitment and regulation of checkpoint proteins, and it coordinates with CENPK to recruit the NDC80 complex 1. KNL1 can bind either microtubules or protein phosphatase 1 catalytic subunits through overlapping binding sites, with higher PP1 affinity 4. Clinically, mutations in KNL1 cause autosomal recessive primary microcephaly (MCPH4), demonstrating its critical role in brain growth 5. Recent evidence indicates KNL1 regulates cytokinesis during cardiomyocyte proliferation through ATF4-mediated transcriptional control 6, highlighting its diverse cellular functions beyond mitotic checkpoint control.