Kallikrein-8 (KLK8) is also known as Neuropsin (NP or NRPN), Ovasin, Serine protease 19 (PRSS19), Tumor-associated differentially expressed gene 14 protein (TADG-14), which belongs to the peptidase S1 family and Kallikrein subfamily. KLK8 contains 1 peptidase S1 domain. KLK8 is pH dependence protein and the optimum pH is 8.5, and the protein is active from pH 7-10. KLK8 is expressed at high levels in serum, ascites fluid and tumor cytosol of advanced stage ovarian cancer patients and may serve as a marker of ovarian cancer. KLK8 cleavage of amide substrates following the basic amino acids Arg or Lys at the P1 position, with a preference for Arg over Lys, and the catalytic activity of KLK8 is inhibited by a range of serine protease inhibitors including antipain, aprotinin, leupeptin, benzamidine and soybean trypsin inhibitor.