This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
Which of the following cell type(s) secretes prostate specific antigen (PSA)? 
Select and explain. 
A. Benign prostate epithelial cells only, B. Malignant prostate epithelial cells only, C. Benign and malignant prostate epithelial cells, D. Prostate stromal cells
C: Benign and malignant prostate epithelial cells
Answer: C: Benign and malignant prostate epithelial cells 
Explanation: Prostate-specific antigen (PSA), a glycoprotein with a MW of 34,000, is a biological marker used in the detection of prostate cancer. It is secreted from prostatic epithelial cells and is responsible for aiding liquefaction of semen. This marker, which is evaluated with a blood test, can be produced by both benign and malignant epithelial cells. The prostate stromal cells do not produce PSA. Ref:Barrett K.E., Barman S.M., Boitano S., Brooks H.L. (2012). Chapter 23. Function of the Male Reproductive System. In K.E. Barrett, S.M. Barman, S. Boitano, H.L. Brooks (Eds), Ganong's Review of Medical Physiology, 24e.