It has been applied to the early diagnosis of cancer markers and infectious diseases such as prostate-specific antigen (PSA)[15,16], human chorionic gonadotropin and α-fetoprotein[25], amyloid-ß-derived diffusible ligand[26], interleukin-2[23], Hantaan viral nucleocapsid protein[22] and HIV-1 p24 antigen[17,19,21]. Here, KLK3 is linked to cancer.