KLK3 and prostate cancer: These findings opened several new diagnostic approaches, including a highly sensitive mass-spectrometry-based analysis of glycan structures of PSA and a sandwich enzyme-linked immunosorbent assay system coupled with a PSA antibody and Wisteria floribunda agglutinin (WFA), which recognizes a terminal GalNAc residue, to discriminate patients with prostate cancer in a gray zone from those with BPH [42,43,44].