Immunohistochemical studies have shown PDE5 immunolocalization mainly in the fibromuscular stroma and vascular (endothelial and stem) cells in the rat and human prostate of BPH subjects [33], as well as in the glandular and subglandular areas of human prostate cancer (Pca) patients [34]. This evidence concerns the gene PDE5A and benign prostatic hyperplasia.