Overproduction of KLK4 by nonmalignant prostate lesions, which are often considered as precursors of PCa, or at least are associated with the presence of PCa (Chrisofos et al., 2007; Eminaga et al., 2013), and at the interface of epithelial cells and stroma, highlights a possible involvement of KLK4 in mediating interactions between epithelium and stromal cells in the early stages of PCa development. Here, KLK4 is linked to posterior cortical atrophy.