SEPTIN9 is a filament-forming cytoskeletal GTPase that plays a structural role in cell division and cytoskeleton organization 1. The protein functions within septin complexes and is involved in cytokinesis and organization of actin and microtubule cytoskeletons 1. In glioblastoma cells, SEPTIN9 overexpression promotes tumor growth through p53/p21 and MEK/ERK signaling pathways; knockdown suppresses cell proliferation, arrests cells in S phase, and reduces invasive capacity 1. Clinically, SEPTIN9 has significant relevance as a cancer biomarker. Methylated SEPTIN9 (mSEPT9) in plasma demonstrates diagnostic value for colorectal cancer, with sensitivity of 71.8% in CRC patients versus 6.1% in healthy controls 2. The mSEPT9 test outperforms traditional markers like CEA and CA19-9 for CRC detection 3, and combined with other biomarkers provides improved diagnostic efficacy 2. mSEPT9 also shows promise for hepatocellular carcinoma diagnosis in elderly patients, with 87.1% negative conversion rate after surgery 4. Additionally, SEPTIN9 methylation has emerged as a potential screening marker for esophageal cancer 5. However, current evidence does not support using serum SEPTIN9 assay for colorectal cancer screening in general populations 6. SEPTIN9 mutations are associated with hereditary neuralgic amyotrophy 7.