PSG4 (pregnancy specific beta-1-glycoprotein 4) is a member of the pregnancy-specific glycoprotein family that plays important roles in cellular senescence regulation and pregnancy-related processes 1. The protein functions as a molecular driver for cellular aging, with significantly increased expression observed in preterm placentas compared to term placentas, where it localizes primarily to villous syncytiotrophoblast, cytotrophoblast, and the intervillous space 2. PSG4 demonstrates conserved TGF-β1 activation capability, converting latent TGF-β1 to its active form in both soluble and extracellular matrix-bound states, potentially contributing to immune tolerance during pregnancy 3. The gene exhibits a type IIa domain arrangement (L-N-A1-B2-C) and belongs to the carcinoembryonic antigen family 4. In cellular senescence contexts, PSG4 expression levels correlate with cell cycle regulation and act as a pivotal regulator of replicative senescence in human dental pulp stem cells 1. Clinically, elevated PSG4 plasma levels serve as a biomarker for predicting cerclage failure in cervical insufficiency cases and show promise for identifying women at risk for preterm delivery 52. Additionally, PSG4 participates in regulating viral gene transcription, specifically influencing hepatitis B virus gene expression in embryonic development 6.