Comparison of KLK4 immunostaining intensity for tissue sections with different histological types is presented in Table S2 and summarized in Fig. 1B. The abundance of KLK4 in BPH, PIN, Gleason 3, 4 and 5 cancers was significantly higher than in the normal prostate (P < 0.05). Here, KLK4 is linked to benign prostatic hyperplasia.