FAP and prostate cancer: Importantly in prostate cancer, preclinical studies have shown that the presence of an altered or ‘reactive’ stroma is a predictor of poor prognosis and that high expression of cancer-associated fibroblast (CAF) markers Fibroblast Activation Protein (FAP) and Alpha-Smooth Muscle Actin (α-SMA) predict biochemical recurrence of disease in prostate cancer patients [4,5].