Galectin-1 is a member of the galectin family, and binds B-galactosidase moieties on glycoproteins or glycolipids. Galectins are primarily involved in modulation of cell-cell and cell-matrix interactions. Galectin-1 acts as a negative regulator of immunity, promoting immune suppression and lessening the inflammatory response. Galectin-1 binds CD45, CD3 and CD4, resulting in the inhibition of CD45 phosphatase dependant dephosphorylation of lyn kinase, as well as a number of other immune related receptors. Due to its function as a negative regulator of the immune response, and role inducing apoptosis in activated Th1 and Th17 cells, it is commonly found upregulated around malignant tumours. It has also been implicated as having a role in the development of immune tolerance during pregnancy, and is highly expressed at the maternal-fetal interface. As a dimer it down-regulates neutrophils by inducing exposure of phosphatidylserine, thereby marking the cell for apoptosis. It shares approximately 88% and 90% sequence similarity with mouse and rat galectin-1, respectively. Recombinant Human Galectin-1 is a 14.9kDa protein.