PRSS8 is a member of the trypsin family of serine proteases. It can be found in seminal fluid and is highly expressed in prostate epithelia. The proprotein is cleaved to produce a light chain and a heavy chain which are associated by a disulfide bond. The carboxyterminal region contains a GPI anchor sequence, which anchors prostasin to the cell surface. Phospholipase activity is thought to liberate prostasin from the cell, and cleavage of the linker region also releases prostasin. PRSS8 has been proposed as a marker for ovarian cancer, where it is up-regulated, a marker for androgen-refractory prostate cancer, where it is down-regulated, and as an inhibitor of invasiveness in breast cancer.