KLK1 and prostate cancer: The KLKs are a class of secreted serine proteases with trypsin or chymotrypsin activity, consisting of 15 members (KLK1‐15).[3, 4] The KLK family is well known for the role of KLK1 in the kallikrein‐kinin system and the clinical applicability of KLK3 as a biomarker for prostate cancer screening.[5] Kinin is one of the inflammatory mediators, the most common kinins are bradykinin (BK) and lysyl‐bradykinin (Lys‐BK), also known as kallidin.