Several prostate cancer (PCa) cell lines display increased level of PDE5 expression (113), and PDE5 inhibitors can sensitize cancer cells to chemotherapeutic agents, either by reducing extrusion of the chemotherapeutics agents by ABCB1, ABCC1 and ABCG2 transporters (114) or by promoting apoptosis (115). The gene discussed is PDE5A; the disease is prostate cancer.