LIGHT is a cytokine belonging to the TNF family. This cytokine has been extensively defined in its role on T-cell regulation and dendritic cell maturation. It also exhibits the role in liver regeneration. We recently identified its role in regulation of hematopoietic stem cell differentiation. However, the question whether this cytokine regulates mesenchymal stem cells (MSCs) proliferation and/or differentiation remains unknown. In this study, we observed that MSCs express LT-βR but not HVEM. PCR analysis show LIGHT mRNA is undectable in MSCs. LIGHT did promote neither MSCs proliferation nor migration. However, LIGHT promoted MSCs differentiation into adipocyte which was confirmed by Oil Red O Staining Assay. Since either MSCs or adipocytes are the major cell population in bone marrow niche, we then suggest that LIGHT regulate bone marrow niche, such as MSCs differentiation. J. Cell. Biochem. 114: 346–353, 2013. © 2012 Wiley Periodicals, Inc.