The upregulation of SLeX has been detected on PSA, Mucin 1 (MUC1), and prostatic acid phosphatase (PAP) proteins in a panel of 10 malignant tissues (relative to matched normal tissue), opening up a new avenue for the development of prostate cancer-specific glycoprotein biomarkers [57]. This evidence concerns the gene KLK3 and Familial prostate cancer.