KLK4 and neoplasm: Indeed, simultaneous expression of KLK4, KLK5, KLK6, and KLK7 in ovarian cancer cells resulted in an increase in tumor burden in vivo (Prezas et al., 2006), KLK7 increased esophageal adenocarcinoma cell proliferation (Xi et al., 2015), and we have recently revealed that in colon cancer cells overexpressing KLK7 proliferation was increased in vitro and, moreover, these cells developed larger tumors in nude mice (Walker et al., 2014).