SYPL1 (synaptophysin-like 1) is a tetratransmembrane transport vesicle protein localized to synaptic vesicle membranes and extracellular exosomes 1. It functions in vesicle trafficking, particularly within trans-Golgi network (TGN)-derived transport systems, where it localizes to TGN vesicles during spermiogenesis 2. SYPL1 is involved in protein binding interactions, including with hNOT/ALG3 and factors regulating endoplasmic reticulum processes 3. Clinically, SYPL1 serves as a promising biomarker across multiple cancer types. In colorectal cancer, fecal SYPL1 demonstrates superior diagnostic performance (AUC=0.947) for screening and early detection, correlating with tumor characteristics and therapeutic response 4. In hepatocellular carcinoma, SYPL1 overexpression independently predicts poor prognosis and associates with epithelial-mesenchymal transition (EMT), with elevated expression correlating with reduced overall and disease-free survival 5. SYPL1 is upregulated in oral squamous cell carcinoma through the YY1/Kcnq1ot1/miR-506-3p/SYPL1 regulatory axis 6 and in colorectal cancer via the circ_0004104/miR-493-5p/SYPL1 cascade, promoting cell proliferation and migration 7. SYPL1 is also identified as a potential seed gene in papillary thyroid carcinoma pathogenesis 8. Additionally, serum SYPL1 is a diagnostic marker for neuroendocrine neoplasms 1.