In previous studies, many tumor-specific promoters, such as the mucin-1 promoter for breast cancer [34], the prostate-specific antigen (PSA) promoter for prostate cancer [35], and the mesothelin promoter for ovarian cancer [36], have been investigated for use in the detection or treatment of primary tumors and their metastatic lesions. The gene discussed is KLK3; the disease is prostate carcinoma.