In addition, a recent study found that the cyclic guanosine monophosphate/protein kinase G (cGMP/PKG) signal pathway activated by PDE5-I can suppress the infiltration of CD8 T-cell and the expression of CCL5 and cyclin D1, thus inhibiting the proliferation of BPH epithelial cells [95]. This evidence concerns the gene CD8A and benign prostatic hyperplasia.