kallikrein-related peptidase 11 (KLK11), also known as hippostasin, trypsin-like serine protease and PRSS20, is a member of human tissue kallikrein family. It is a subgroup of serine proteases with diverse physiological functions, which is implicated in carcinogenesis and some with potential that serving as novel biomarkers for ovarian and prostate cancer and other diseases. The KLK11 gene is one of the fifteen kallikrein subfamily members located in a cluster on chromosome 19. Two alternatively spliced forms exist, resulting in 250 (isoform 1) and 282 (isoform 2) amino acid sequences. Isoform 2 is identical to isoform 1, except for an inserted 32 amino acid segment. Isoform 1 is predominantly expressed in brain whereas isoform 2 is preferentially expressed in prostate.