KLK3 and prostate cancer: Applying the AAL–PSA and LCA–PSA assays to the prostate cancer serum samples, we observed significant differences in serum PSA levels among Gleason 6, Gleason 7 and Gleason 8, 9 for fucosylated PSA–AAL (Kruskal–Wallis; p = 0.014) (Fig. 2a).