KLK5 and lung carcinoma: In lung carcinoma, the mRNA level of kallikrein‐related peptidase 5 (KLK5) showed a decrease after knocking down PRSS3, and low expression of KLK5 impaired cell invasiveness.[63] Since PRSS3 was able to process pro‐KLK5 to active KLK5,[64] KLK5 has been proposed as a potential substrate of PRSS3.