SECTM1 (Secreted and Transmembrane 1) is a type 1a membrane protein that exists in both transmembrane and soluble secreted isoforms 1. Localized to the Golgi apparatus, SECTM1 functions primarily in immune regulation and wound healing. As a T/NK cell co-stimulatory molecule 2, SECTM1 is expressed by myeloid cells and acts as an interferon early response gene, rapidly upregulated by IFN-α/β/γ while being negatively regulated by LPS 2. Mechanistically, SECTM1 promotes limbal stem cell migration and proliferation during corneal wound healing, potentially through CDCA7 3, with topical application improving re-epithelialization in aged animals 3. In cancer pathology, SECTM1 promotes glioblastoma progression via TGFβ1/Smad-mediated epithelial-mesenchymal transition 4, and drives esophageal squamous cell carcinoma advancement by promoting M2 macrophage polarization through CCL5 5. SECTM1 serves as an immune-related prognostic biomarker in multiple malignancies 5. Cardiovascularly, SECTM1 functions as a monocyte chemoattractant, with the rs116473040 variant associated with increased proatherogenic Ly6Chi monocytes and incident coronary heart disease 6. These functions reflect SECTM1's broader role in regulating immune cell recruitment and differentiation across physiological and pathological contexts.