FASLG (Fas ligand, CD95L, CD178) is a tumor necrosis factor transmembrane protein found on cytotoxic T lymphocytes that functions to induce apoptosis. FASLG and the FAS receptor are immune system regulators involved in programmed cell death processes such as in the negative selection of thymocytes. FASLG also plays a role in the progression of multiple sclerosis and in tumorigenesis. It functions under normal conditions to maintain the immune suppressed status in the central nervous system, but expression has been found to increase and to contribute to neuronal degeneration and inflammation in the brain in various neurological and neurodegenerative disorders. In immunohistochemistry, FASLG has cytoplasmic positivity in various tissues throughout the body, including the central nervous system, thyroid, gastrointestinal tract, pancreas, kidney, reproductive tissues, immune cells and blood. References: Front. Immunol. 2016. DOI: 10.3389/fimmu.2016.00382; Brain Res Brain Res Rev. 2004 Jan;44(1):65-81, PMID: 14739003;