PSG1 (pregnancy-specific beta-1-glycoprotein 1) is a trophoblast-secreted immunoglobulin superfamily member that functions as a critical regulator of maternal-fetal interactions during pregnancy 1. Mechanistically, PSG1 promotes endothelial cell proliferation and vascular development primarily through the TGF-β/Orai3 signaling pathway, enhancing nitric oxide production and intracellular calcium levels in human umbilical vein endothelial cells 2. PSG1 also regulates trophoblast cell migration via the Orai1/Akt pathway, processes essential for placental development 3. The protein is internalized by platelets and influences platelet function during pregnancy 4. Beyond pregnancy, PSG1 expression serves as a biomarker of skin aging in dermal fibroblasts 5. Pathologically, elevated PSG1 expression promotes gastric cancer progression, correlating with poor prognosis and enhanced cell proliferation, migration, and invasion 6. In breast cancer, PSG1 mediates chemoresistance through TGF-β-related pathways and can be pharmacologically targeted using dicumarol 7. Conversely, decreased serum PSG1 levels are associated with early-onset preeclampsia, suggesting impaired trophoblast migration 3. These findings establish PSG1 as a multifunctional protein with critical roles in normal pregnancy physiology and aberrant involvement in cancer and pregnancy pathologies.