To verify that KLK4‐mediated gene regulation was not only limited to WPMY1 cells, we analysed the effect of KLK4 on gene expression in patient‐derived primary cultures of nonmalignant fibroblasts (NPFs) from two patients with PCa (NPF1 and NPF2, Fig. 5A–C). Here, KLK4 is linked to posterior cortical atrophy.