The human kallikrein (KLK) family consists of 15 genes located on human chromosome . KLK11⁄hippostasin is a member of the kallikrein family and is expressed in various tissues. Two types of KLK11 isoforms, isoform 1 and isoform 2, have been predicted from cDNA sequences. Iso-form 1 has been isolated from human hippocampus, whereas isoform 2 has been isolated from prostate.