kallikrein

Prekallikrein is the precursor of plasma kallikrein. It can only activate kinins after being activated itself by factor XII or other stimuli.

Kallikreins are targets of active investigation by drug researchers as possible biomarkers for cancer.

Prostate-specific antigen (PSA; hk3, human kallikrein gene 3) and human glandular kallikrein (hK2) are used as tumor markers for prostate cancer.