S1PR3 is a receptor for the lysosphingolipid sphingosine 1-phosphate (S1P). S1P is a bioactive lysophospholipid that elicits diverse physiological effect on most types of cells and tissues. It is thought to participate in regulating vascular endothelial cell function and angiogenesis. When expressed in rat HTC4 hepatoma cells, it is capable of mediating S1P-induced cell proliferation and the suppression of apoptosis. Metastatic cancers in the brain can overexpress S1PR3 as part of the neuroinflammatory response, and it is implicated in regulating blood brain barrier permeability. In immunohistochemistry, it has variable membranous positivity in most tissues throughout the body. References: Nat Commun 9, 2705 (2018) doi:10.1038/s41467-018-05030-w