Kallikreins belongs to the family of trypsin-like serine proteases, many of which are associated with a variety of cancers. Kallikrein 1 (KLK1) is also known as tissue kallikrein and urinary kallikrein. KLK1 is synthesized as a 261 amino acid (aa) protein that contains a 18 aa signal peptide and a 241 aa proprotein. An important physiological function of KLK1 cleaves Met-Lys and Arg-Ser bonds in kininogen to release Lys-bradykinin. Kinins regulate vasodilation, blood pressure reduction, smooth muscle relaxation and contraction, pain induction and inflammation.