Tetherin, also known as bone marrow stromal antigen 2, is a lipid raft associated protein that in humans is encoded by the BST2 gene. In addition, tetherin has been designated as CD317 （cluster of differentiation 317）. This protein is constitutively expressed in mature B cells, plasma cells and plasmacytoid dendritic cells, and in many other cells, it is only expressed as a response to stimuli from IFN pathway.Tetherin has been shown as a Type-I-IFN biomarker using flow cytometry, B cell Tetherin was used as a Cell-Specific Assay for Response to Type I Interferon Predicts Clinical Features and Flares in Systemic Lupus Erythematosus. Tetherin has also been predicted to be involved in cell adhesion and cell migration. Recently it has, also, been identified as the protein that help stabilize lipid rafts by joining nearby lipid rafts to form a cluster. For some viruses, such as Dengue virus, tetherin inhibits the budding of virions as well as cell-to-cell transmission of the virus. For human cytomegalovirus （HCMV）, tetherin promotes entry of the virus, especially during cell differentiation. It has also been shown that tetherin is incorporated into newly formed virions.